Search

Objective: Renal dysfunction is a major cause of morbidity in patients with spinal cord injury (SCI). A 24‐h urine creatinine (Cr) clearance (24‐h urine CCr) is cost‐effective and easy to implement compared to renal scintigraphy in the evaluation of renal function. This study aimed to verify the feasibility of 24‐h urine CCr in the SCI population by assessing the correlation with effective renal plasma flow (ERPF) on renal scintigraphy. Methods: Data from 245 SCI patients (189 males, mean age: 50.2 years) were used in this retrospective review. Clinical characteristics, 24‐h urine CCr, serum Cr, comorbidities, and body composition analyses were assessed for correlation with laboratory parameters including renal scintigraphy. Strong predictors of ERPF were determined by multivariate linear regression analysis. Areas under receiver‐operating characteristic curves were calculated to evaluate the discriminating power of 24‐h urine CCr to predict ERPF <250 ml/min. Results: Spinal cord injury patients showed tubular dysfunction despite normal serum Cr and 24‐h urine CCr. There was a significant correlation between 24‐h urine CCr and ERPF, and 24‐h urine CCr was one of the strongest predictors for ERPF (area under the curve 0.72, 95% CI 0.64–0.80, p < 0.000) among other parameters such as age, appendicular lean mass index, and body mass index. 24‐h urine CCr was an independent predictor of ERPF in subacute (R2 = 0.497, p < 0.001) and chronic SCI patients (R2 = 0.664, p < 0.0001). The optimized 24‐h urine CCr cut‐off was 139.4 ml/min/1.72 m2 for predicting decreased ERPF <250 ml/min (sensitivity 67.6% and specificity 64.0%). Conclusion: 24‐h urine CCr is a sensitive indicator for renal function deterioration of SCI patients. Further longitudinal studies with larger numbers of SCI patients are needed to confirm the feasibility of 24‐h urine CCr for monitoring this population. [ABSTRACT FROM AUTHOR]

Background and Objectives: In chronic kidney obstruction, the severity of tubulointerstitial damage correlates best with the loss of kidney function and the risk for progression to end-stage kidney disease. The present study aimed to investigate the potential clinical significance of serum uromodulin (sUmod) as a marker of early kidney disfunction in patient with obstructive nephropathy (ON). Materials and Methods: Serum Umod level was measured by sensitive ELISA method in 57 adult patients with obstructive nephropathy and 25 healthy subjects in control group. Kidney function was precisely evaluated via measured glomerular filtration rate (mGFR) (renal clearance of 99 mTc-diethylenetriamine penta-acetic acid), effective renal plasma flow (ERPF) and Cystatin C level. Recruited patients were divided into subgroups based on the mGFR: group I—GFR ≤ 60 mL/min/1.73 m2 (N = 31), group II—GFR > 60 mL/min/1.73 m2 (N = 26). Results: A significantly lower level of serum uromodulin was measured in patients with ON (50.2 ± 26.3 ng/mL) compared to the control group (78.3 ± 24.5 ng/mL) (p < 0.001). The mean level of serum Umod was significantly different between group I (30.5 ng/mL ± 11.1) and group II (73.6 ng/mL ± 18.6) (p < 0.001), but not between group II (73.6 ng/mL ± 18.6) and control group (78.3 ± 24.5 ng/mL). There was a positive correlation between sUmod and mGFR (R = 0.757, p < 0.001) and ERPF (R = 0.572 p < 0.001), with lower sUmod levels in patients with impaired renal function. An inverse relationship was detected between sUmod and filtration markers—cystatin C (R = −0.625, p < 0.001), creatinine, urea and uric acid. ROC analysis of sUmod to differentiate between ON patients with GFR below 60 mL/min/1.73 m2 and above 60 mL/min/1.73 m2 resulted in AUC of 0.98 (p < 0.001, 95% CI 0.922 vs. 0.998) at a cut-off value of 46 ng/mL (specificity 96.8%, sensitivity 92.2%). Conclusions: The significant correlation of sUmod with kidney function parameters may imply potential clinical significance as a noninvasive biomarker of early kidney disfunction in obstructive nephropathy. [ABSTRACT FROM AUTHOR]

Background: Changes in renal blood flow (RBF) may play a pathophysiological role in hypertension and kidney disease. However, RBF determination in humans has proven difficult. We aimed to confirm the feasibility of RBF estimation based on positron emission tomography/computed tomography (PET/CT) and rubidium-82 (82Rb) using the abdominal aorta as input function in a 1-tissue compartment model. Methods: Eighteen healthy subjects underwent two dynamic 82Rb PET/CT scans in two different fields of view (FOV). FOV-A included the left ventricular blood pool (LVBP), the abdominal aorta (AA) and the majority of the kidneys. FOV-B included AA and the kidneys in their entirety. In FOV-A, an input function was derived from LVBP and from AA, in FOV-B from AA. One-tissue compartmental modelling was performed using tissue time activity curves generated from volumes of interest (VOI) contouring the kidneys, where the renal clearance of 82Rb is represented by the K1 kinetic parameter. Total clearance for both kidneys was calculated by multiplying the K1 values with the volume of VOIs used for analysis. Intra-assay coefficients of variation and inter-observer variation were calculated. Results: For both kidneys, K1 values derived from AA did not differ significantly from values obtained from LVBP, neither were significant differences seen between AA in FOV-A and AA in FOV-B, nor between the right and left kidneys. For both kidneys, the intra-assay coefficients of variation were low (~ 5%) for both input functions. The measured K1 of 2.80 ml/min/cm3 translates to a total clearance for both kidneys of 766 ml/min/1.73 m2. Conclusion: Measurement of renal perfusion based on PET/CT and 82Rb using AA as input function in a 1-tissue compartment model is feasible in a single FOV. Based on previous studies showing 82Rb to be primarily present in plasma, the measured K1 clearance values are most likely representative of effective renal plasma flow (ERPF) rather than estimated RBF values, but as the accurate calculation of total clearance/flow is very much dependent on the analysed volume, a standardised definition for the employed renal volumes is needed to allow for proper comparison with standard ERPF and RBF reference methods. [ABSTRACT FROM AUTHOR]

Measurement of the concentration of hippurate in the inferior vena cava and renal blood samples performed in 13 subjects with normal or near‐normal serum creatinine concentrations confirmed the prediction that endogenous hippurate was cleared on a single pass through the kidney with the same avidity as that reported for infused para‐amino hippurate. This suggests that a timed urine collection without infusion would provide a measure of effective renal plasma flow. Comparison of the arteriovenous concentration differences for a panel of protein‐bound solutes identified solutes that were secreted by the renal tubule and solutes that were subjected to tubular reabsorption. [ABSTRACT FROM AUTHOR]

Copyright of Pocki is the property of Zaslavsky O.Yu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aim: Elevated fractional excretion of magnesium (FEMg) is a noninvasive biomarker of kidney damage, but its association with kidney functional parameters in nondiabetic chronic kidney disease (CKD) patients has not been sufficiently explored thus far. Methods: We enrolled 111 adult patients with nondiabetic CKD and 30 controls. To precisely investigate kidney function, the following parameters were assessed measured glomerular filtration rate (mGFR), effective renal plasma flow (ERPF), Cystatin C, albuminuria, and fractional excretion of magnesium (FEMg). All the CKD patients were divided into two groups according to the values of mGFR (mL/min/1.73m²): the first group consisted of those with GFR≥ 60 mL/min/1.73m², whereas the second group included those with GFR< 60 mL/min/1.73m². Results: FEMg (%) was significantly higher in the group of nondiabetic patients with CKD compared to the healthy subjects [6.3 vs. 5.3%, P=0.013]. There was also significant difference in the value of FEMg between the first and second groups of CKD patients. Increased FEMg was significantly correlated with all the investigated kidney function parameters, mGFR, ERPF, Cystatin C and albuminuria (r=-0.62; r=-0.60; r=0.77; r=0.39; p<0.01 for all). In multiple regression analyses based on observed parameters of kidney function, only cystatin C was independently and significantly associated with FEMg (multiple correlation coefficients: 0.738, p < 0.001)). Nondiabetic CKD patients with GFR< 60 mL/min/1.73m² have increased FEMg above 6.1% with 78.7% specificity and 83.7% sensitivity. Conclusion: Highly significant association between kidney functional parameters and FEMg may indicate significance of this parameter in clinical practice. [ABSTRACT FROM AUTHOR]

The aim was to assess the effect of standard fixed-dose protocol of 177Lu-DOTATATE peptide receptor radionuclide therapy (PRRT) in patients with borderline low renal function of one parameter (glomerular filtration rate [GFR], effective renal plasma flow [ERPF] or serum creatinine), that was discordant with the remaining parameters and determine the feasibility of this procedure in this group of patients. Renal toxicity of PRRT is a routine issue or concern for such cases. We compared different renal parameters used for pretherapy assessment in patients with borderline low single parameter at baseline and their potential significance with regards to deterioration of renal function subsequently. A retrospective analysis was performed in patients of metastatic neuroendocrine tumors who received therapeutic 177Lu-DOTATATE (using standard fixed-dose protocol) and had borderline compromised renal parameter values (either of GFR/ERPF/serum creatinine). Filtration fraction (FF) was also estimated in each case and all renal parameters were correlated using kappa statistics. The characteristics of cases showing progressive worsening of renal function in the follow-ups were also studied. A total of 15 patients (11 males, 4 females; age range: 32-75 years) were selected among a population of 450 patients. The follow-up duration ranged from 10 to 48 months and administered cumulative activity ranged 9.9-31.3 GBq (2-5 cycles). Based on the parameter characteristics, the study population was divided into following four groups: (a) patients with reduced GFR and maintained ERPF and normal serum creatinine (n = 3); (b) patients with reduced ERPF with maintained GFR and borderline elevated/normal serum creatinine (n = 3); (c) patients with both reduced GFR and ERPF and maintained serum creatinine (n = 1); (d) patients with compromised single kidney function (n = 5). A total of four patients were found who had normal baseline renal function values but showed progressive worsening in the subsequent period. There was no significant change in renal parameters during the follow-up in both Groups a and c. Two patients of Group b demonstrated well-maintained other renal parameters, whereas in 1 patient, there was the evidence of renal toxicity with gradual fall of GFR and ERPF and progressive increase in serum creatinine level. In patients with compromised single kidney function at baseline (Group d), there was overall maintained normal renal parameters, whereas 3 of 5 (60%) showed the increase of FF of the affected kidney. Interestingly, a compensatory hyperfunction was noted in the contralateral kidney. PRRT with 177Lu-DOTATATE is feasible and can be considered in patients with reduced GFR and with maintained ERPF and normal serum creatinine and also in the presence of single compromised parameter if the other two are normal; however, these patients need critical monitoring. [ABSTRACT FROM AUTHOR]

Background: Endothelin-1 (ET-1) is potent vasoconstrictor peptide which is able to contribute to the functional and structural renal changes. The aim of this study was to investigate the relationship between plasma concentration of ET-1 and indices of renal function in patients with diabetic nephropathy. Methods: We measured plasma ET-1 levels in 99 patients with type 2 diabetes, divided into two groups according to the values of their glomerular filtration rate (GFR): group I (GFR ≥ 60 mL/min/1.73 m2; n = 50), group II (GFR ≥ 60 mL/min/1.73 m2, n = 49), and the control group ( n = 30) with clinically healthy subjects who were matched by age and sex. GFR and effective renal plasma flow (ERPF) were measured by the radioisotopic clearance. Other renal function parameters, such as serum concentrations of cystatin C, urea, creatinine, uric acid, 24-h albuminuria and proteinuria were additionally measured. Results: There were significant differences in plasma concentration of ET-1 among groups I, II and the control group (1.45 vs. 2.40 vs. 0.80 pg/mL, p < 0.001). The correlation between ET-1 and mGFR ( r = −0.52, p < 0.001), ERPF ( r = −0.42, p < 0.001), albuminuria and proteinuria ( r = 0.36, p < 0.001; r = 0.48, p < 0.001) and cystatin C ( r = 0.42, p < 0.001) was significant. In multiple regression analyses, only plasma concentration of ET-1 ( p < 0.001) and duration of hypertension ( p < 0.05) were independently and significantly associated with mGFR. Conclusion: A higher plasma concentration of ET-1 is independently associated with a decreased value of GFR in patients with diabetic nephropathy. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Physiology & Pharmacology is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background/Aims: Cigarette smoking is a risk factor for renal damage, but little is known about subclinical effects of smoking on renal hemodynamics and parameters of renal function in humans. We examined the associations of smoking with systemic and renal hemodynamics and renal function parameters in healthy individuals. Methods: Data from 196 potential living kidney donors were analysed retrospectively. Mean arterial blood pressure (MAP), effective renal plasma flow (ERPF) and creatinine clearance had been measured. We additionally calculated parameters of renal hemodynamics. Data were analyzed for the effects of smoking and sex dependent on age and MAP. Results: Systemic and renal hemodynamic parameters did not differ between smokers and non-smokers. In non-smokers of both sexes MAP was negatively correlated with ERPF, and higher MAP was associated with increased renal vascular resistance and with afferent arteriolar resistance, with glomerular pressure (PG) remaining constant. However, in male, but not in female smokers, ERPF and PG increased with MAP. A correlation of age with a steeper decline in ERPF in male smokers was lost in multiple regression analysis. Conclusions: As compared to women, smoking men may exhibit an increased glomerular hydrostatic pressure, which is a known promoter of kidney damage. © 2014 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Several single sample methods for determination of 99m Tc-mercaptoacetyltriglycine ( MAG3) clearance are being used clinically. Kabasakal et al. proposed a similar formula for 99m Tc-ethylenedicysteine ( EC). This study was performed to compare his method with Bubeck et al. formula for 99m Tc- MAG3 already in use. Twenty-eight subjects divided in two groups were registered which included 22 patients with various renal diseases (group-I) and six normal volunteers (group II). All subjects were studied twice using both the radiopharmaceuticals. The images and renogram parameters, that is TMAX and T1/2 of both the agents, were similar in all the subjects. The clearance of the 99mTc- EC was however considerably higher than 99mTc- MAG3 in both the groups (mean ± SEM =279 ± 14 ml min−1/1·73 m2 versus 177 ± 15 ml min−1/1·73 m2 in group-I and 377 ± 11·90 ml min−1/1·73 m2 versus 238 ± 8·23 ml min−1/1·73 m2 in group II). This difference was more pronounced in cases with reduced renal functions. Among the Effective Renal Plasma Flow ( ERPF) values determined from EC and MAG3 clearances in six normal volunteers, four cases only in MAG3 had ERPF below the lower limit. This study has demonstrated superiority of single sample method for 99 mTc- EC clearance over its analogous method for 99m Tc- MAG3. [ABSTRACT FROM AUTHOR]

Introduction: Renal function after renal surgery depends on the volume of renal parenchyma loss and improves in the postoperative period. However, the knowledge on kidney function after radical (RN) and partial (PN) nephrectomy is still insufficient. The aim of this study is to analyze the global renal function and compensatory hyperfunction of the non-operated kidney in patients with renal cancer after RN or PN. Methods: Fifty-one patients of mean age 62.2 years with renal cancer were included. Thirty-three RN and eighteen PN were performed. We measured creatinine serum concentrations, and we estimated glomerular filtration rate (eGFR) preoperatively and postoperatively at two time intervals: 3 and 12 months after surgery. Additionally, we assessed effective renal plasma flow (ERPF) in dynamic scintigraphy preoperatively and 12 months after surgery. Result: At the baseline, all mean measured values were comparable in RN and PN groups ( P > 0.05). Three months after surgery, creatinine level increased in both groups, more remarkably in RN group (128 mmol/l vs. 95 mmol/l; P < 0.05), while eGFR diminished (47 ml/min/1.73 m vs. 70 ml/min/1.73 m; P < 0.05). Similar biochemical values were observed 12 months after surgery. The mean ERPF of the non-operated kidney 12 months after surgery in RN and PN groups increased by 3.8% (232 ml/min) and 0.1% (200 ml/min), respectively ( P > 0.05). The mean ERPF of the operated kidney in PN group decreased by 24.7% (149 ml/min). Conclusion: The deterioration of renal function after partial nephrectomy is nearly insignificant clinically. In 1-year postoperative observation, the renal function does not improve. This causes potential compensatory mechanisms to be insufficient. [ABSTRACT FROM AUTHOR]

Copyright of La Radiologia Medica is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background. Contrast-enhanced ultrasonography (CEUS) is a novel imaging technique that is safe and applicable on the bedside. Recent developments seem to enable CEUS to quantify organ perfusion. We performed an exploratory study to determine the ability of CEUS to detect changes in renal perfusion and to correlate them with effective renal plasma flow. Methods. CEUS with destruction-refilling sequences was studied in 10 healthy subjects, at baseline and during infusion of angiotensin II (AngII) at low (1 ng/kg/min) and high dose (3 ng/kg/min) and 1 h after oral captopril (50 mg). Perfusion index (PI) was obtained and compared with the effective renal plasma flow (ERPF) obtained by parallel para-aminohippurate (PAH) clearance. Results. Median PI decreased from 188.6 (baseline) to 100.4 with low-dose AngII (−47%; P < 0.02) and to 66.1 with high-dose AngII (−65%; P < 0.01) but increased to 254.7 with captopril (+35%; P > 0.2). These changes parallelled those observed with ERPF, which changed from a median of 672.1 mL/min (baseline) to 572.3 (low-dose AngII, −15%, P < 0.05) and to 427.2 (high-dose AngII, −36%, P < 0.001) and finally 697.1 (captopril, +4%, P < 0.02). Conclusions. This study demonstrates that CEUS is able to detect changes in human renal cortical microcirculation as induced by AngII infusion and/or captopril administration. The changes in perfusion indices parallel those in ERPF as obtained by PAH clearance. [ABSTRACT FROM AUTHOR]

Aims Anaemia is prevalent in the chronic heart failure (CHF) population, but its cause is often unknown. The present study aims to investigate the relation between anaemia, renal perfusion, erythropoietin production, and fluid retention in CHF patients. [ABSTRACT FROM PUBLISHER]

Maternal renal disease is associated with high maternal and fetal morbidity. To establish an animal model to study renal dysfunction in pregnancy and its potential role in programming for renal disease and hypertension in adult life, a kidney was removed from each of 16 nonpregnant ewes, and a branch of the renal artery of the remaining kidney was ligated (STNx ewes). The 16 STNx and 15 intact ewes were time mated 2.5–17 mo later and studied at 119–132 days of gestation. STNx ewes demonstrated renal hypertrophy and glomerular hyper-filtration. They had higher diastolic arterial pressures (P < 0.05) and larger left ventricles (P < 0.0005), drank more water (P < 0.01), were hypochloremic (P < 0.01) and hyperglycemic (P < 0.0005), and had higher plasma creatinine levels (P < 0.0005) than intact ewes. Effective renal plasma flows and glomerular filtration rates were lower (P < 0.01) and protein excretion was greater (P < 0.05) in STNx than in intact ewes. Glomerulotubular balance was impaired in STNx ewes. Proximal tubular Na+ reabsorption was reduced (P < 0.05), so Na+ excretion was increased (P < 0.05). In STNx ewes, filtered K+ loads were reduced (P < 0.005), but K+ excretion was the same as in intact ewes. There was net K+ secretion in STNx ewes; in intact ewes, there was net reabsorption. Plasma renin and angiotensinogen concentrations in STNx and intact ewes were similar, so the hypertension in STNx ewes was not renin dependent. STNx fetuses grew normally, and their blood gases, blood pressure, and heart rates were normal. These alterations in maternal fluid and electrolyte balance and the potential risk of maternal salt depletion or hyperkalemia may adversely affect the fetus. [ABSTRACT FROM AUTHOR]

Abstract Background Patients with heart failure are characterized by impaired nitric oxide-dependent endothelial vasodilation and, in addition, by reduced renal perfusion. Design We assessed blood concentrations of the endogenous nitric oxide synthase inhibitor asymmetric dimethylarginine (ADMA) as well as renal haemodynamics to compare normotensive patients with mild heart failure (n = 12, seven males, 70 ± 1 years, 72·0 ± 2·7 kg, 92 ± 2 mmHg, NYHA I/II) and healthy subjects matched with respect to gender, age and body weight (n = 12, seven males, 69 ± 2 years, 72·7 ± 2·5 kg, 88 ± 2 mmHg). Results Plasma ADMA concentration and renovascular resistance (RVR) were significantly higher (P < 0·01) and effective renal plasma flow (ERPF) significantly lower (P < 0·01) in the patients with heart failure (ADMA 4·18 ± 0·42 µmol L-1 , RVR 159 ± 12 mmHg mL-1 min-1 , ERPF 381 ± 26 mL min-1 1·73 m-2 ) as compared with the healthy controls (ADMA 2·38 ± 0·11 µmol L-1 , RVR 117 ± 8 mmHg mL-1 min-1 , ERPF 496 ± 19 mL min-1 1·73 m-2 ). In contrast, plasma concentrations of l-arginine, homocysteine, symmetric dimethylarginine (i.e. the biologically inactive stereoisomer of ADMA) and plasma renin activity were not significantly different in both groups studied. In the multiple regression analysis, only plasma ADMA concentrations independently predicted reduced ERPF (r = -0·57; P < 0·003). Conclusions In normotensive patients with heart failure plasma ADMA concentrations are markedly increased and related to reduced renal perfusion. Thus accumulation of this endogenous nitric oxide inhibitor may play a role in renal pathology in these patients. [ABSTRACT FROM AUTHOR]

Objective: Increased physical activity is followed by a stimulation of the sympathetic nervous system and this effect is probably more pronounced in patients with chronic renal failure and hypertension than in healthy controls. The role of sustained exercise in hypertensive patients with chronic renal failure, with and without antihypertensive therapy, is unclear, as is hormonal regulation of the renal hemodynamics. We hypothesized that prolonged low-intensity bicycle exercise would have a greater effect in patients with chronic renal failure than in controls, and that antihypertensive treatment would ameliorate these effects. Material and Methods: Glomerular filtration rate (GFR), effective renal plasma flow (ERPF), mean arterial blood pressure (MAP), norepinephrine (NE) and atrial natriuretic peptide (ANP) were measured in the upright position before and during low-intensity exercise for 2 h in healthy controls (n = 8) and in hypertensive patients with moderately reduced renal function who were not taking antihypertensives (n = 7) or who were receiving treatment with captopril (n = 10), enalapril (n = 6) or verapamil (n = 9). Results: GFR tended to decrease and ERPF decreased significantly in healthy individuals when exercise duration was prolonged from 1 to 2 h. An earlier decline in GFR and ERPF was seen in the renal failure patients compared with the controls. Filtration fraction (FF) increased during exercise in all groups except the group taking enalapril. MAP increased in the captopril group during exercise but was unchanged in the other groups. Treatment with captopril produced a more pronounced and earlier fall in exercise-induced GFR than in untreated controls, while verapamil treatment completely blunted the decline in GFR, with a concomitant increase in plasma ANP. No significant changes were seen in plasma NE levels, but urinary NE excretion increased in controls and captopril-treated patients during exercise. Conclusions: The results suggest that prolonged low-intensity exercise has a substantially greater effect on renal hemodynamics in hypertensive renal failure patients than in healthy controls, with negligible changes in plasma NE levels. Verapamil treatment seems to ameliorate the renal effects of exercise on GFR in these patients, and this may in part be mediated via a stimulatory effect on ANP. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the renal effects of cardiac angiography performed with three low-osmolar contrast media (CM): iopromide (IPR), ioversol (IVR) and ioxaglate (IOX). IPR and IVR are non-ionic CM, IOX is an ionic CM. Different parameters of renal function were determined before and 6, 24, 48, 72 hrs after angiography in 45 patients: 15 patients were examined with IPR, 15 with IVR and 15 with IOX. Glomerular effects – Plasma creatinine increased slightly at the 24th hour after IVR and IOX and at 48 hours after IOP. A significant increase in plasma β2-microglobulin was observed, at the same time, only after IOX. A significant decrease in creatinine clearance was found at 6 hours after IOX. No significant variations in glomerular filtration rate (GFR) and in effective renal plasma flow were found at 48 hours after cardiac angiography; while filtration fraction was significantly reduced after IOP and IOX. Tubular effects – A marked decrease in sodium clearance and a relevant increase of urinary activities of different tubular enzymes were found after cardiac angiography with all CM, but were more evident after the ionic CM IOX, than after the two non-ionic agents. These tubular effects reached the maximum between 6 and 24 hours and returned to baseline within 72 hrs after cardiac angiography. In conclusion, slight glomerular effects were observed mainly after IOX. A reversible tubular malfunction was found with the three low-osmolar CM and was more evident after ionic CM IOX, thus suggesting that other mechanisms, besides osmolarity, play a role in tubular toxicity due to CM. In no patient did the glomerular and tubular effects of CM have a clinical relevance. [ABSTRACT FROM AUTHOR]

Abstract Background and Aims: Subacute hepatic failure (SHF) is a fatal complicaton of acute viral hepatitis. Renal failure has been implicated as the main cause of death in this disease. However, renal functional and structural evaluation in such patients have not been performed. The present prospective study evaluated the renal functional and structural abnormalities in patients with subacute hepatic failure. Methods: Fourteen consecutive patients with SHF, 11 with acute liver failure (ALF) and 15 with cirrhosis of the liver (Child's B or C) were included in the present study. All 40 patients had liver disease caused by hepatitis viruses. The glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) estimations were measured in all patients by the use of technetium-99m diethylenetriaminepentaacetic acid and [131I]-labeled ortho-iodohippuric acid, respectively. Ante-mortem or post-mortem liver biopsies were performed in all patients. In three patients with SHF, post-mortem kidney biopsies were also performed. Results: Thirty six percent (5/14) of patients with SHF, 18% (2/11) of patients with ALF and 20% (3/15) of patients with cirrhosis had renal failure. Seven patients with SHF, seven with ALF and nine with cirrhosis died. All the patients with renal failure in each of the three groups were among the deceased patients. Glomerular function was markedly affected among patients with SHF, which was shown by significantly higher (P < 0.05) proteinuria levels (0.367 ± 0.38 g/24 h) compared to levels in patients with ALF (0.178 ± 0.11 g/24 h) and cirrhosis (0.212 ± 0.133 g/24 h). The GFR in SHF (56 ± 27 mL/min per 1.73 m2) and cirrhotic patients (58 ± 36 mL/min per 1.73 m2) was significantly lower compared to those in ALF patients (102 ± 51 mL/min per 1.73 m2; P < 0.05). A significantly higher proportion (P < 0.05) of patients with SHF and cirrhosis (64 and 73%, respectively) had a GFR below 80 mL/min per 1.73 m2 compared to patients with ALF (18%). The GFR value among the deceased SHF patients (46 ± 26 mL/min per 1.73 m2) was significantly lower (P < 0.05) than those SHF patients who survived (65 ± 25 mL/min per 1.73 m2). However, similar features could not be documented among patients with ALF or cirrhosis. Subtle structural changes in the glomerulus were also noted in patients with SHF. These included mesangial proliferation and thickening, basal membrane thickening and increased cellularity with interstitial edema. The ERPF was markedly reduced (P = 0.058) among patients with SHF (347 ± 131 mL/min per 1.73 m2) and cirrhosis (395 ± 137 mL/min per 1.73 m2) in comparison to ERPF documented among patients with ALF (436 ± 217 mL/min per 1.73 m2). Such a reduction in renal tubular blood flow, along with histologic documentation of hyaline presence, bile and grannular cast in the tubule, indicated a possible tubular dysfunction in patients with SHF. Conclusion: It is concluded that glomerular and tubular dysfunction with subtle structural abnormalities does occur in patients with SHF. These are similar to renal changes in cirrhosis and may have similar pathogenetic mechanisms that require further evaluation. [ABSTRACT FROM AUTHOR]

AbstractBackground and Aims: Isosorbide-5-mononitrate (ISMO) has been shown to be effective in reducing the risk of variceal bleeding in patients with cirrhosis. However, recent studies have suggested that this drug compromises renal function. The present study was conducted to assess the acute and chronic effects of ISMO on effective renal plasma flow (ERPF) and the renin-aldosterone profile in cirrhotic patients. Methods: Fifteen cirrhotic patients were included in the present study. The mean arterial pressure (MAP), heart rate (HR), serum renin concentration (SR), ERPF and plasma aldosterone concentration (PA) were checked before ISMO treatment (baseline study), after a single oral dose of 20 mg ISMO (acute effect study) and after 3 weeks of ISMO treatment (chronic effect study). Results: Our data showed that the oral administration of a single dose (20 mg) of ISMO to cirrhotic patients was associated with significant decreases in ERPF (from 405.18 to 369.06 mL/min) and MAP (from 93.26 to 86.40 mmHg), and increases in HR (from 65.53 to 70.06 beats/min), SR (from 24.15 to 54.41 pg/mL), and PA (from 105.1 to 148.7 pg/mL). However, no significant changes were observed in HR, MAP, PA, SR, or ERPF after 3 weeks of ISMO treatment when compared with the baseline study. Conclusions: The administration of ISMO causes a decrease in ERPF in cirrhotic patients and its use in patients with renal impairment should be considered cautiously. [ABSTRACT FROM AUTHOR]

Background. In essential hypertension, acute haemodynamic changes due to dietary protein load cause patterns of acute changes in renal function that are fundamentally different from changes in normal controls. [ABSTRACT FROM PUBLISHER]

The present study evaluated whether chronically administered low-dose (<5 mg/kg) ciclosporin A (CsA) affects renal haemodynamics and tubular function in renal transplant recipients (RTx) when studied at nadir CsA blood levels. The renal clearance of lithium was used as an index of proximal tubular outflow of sodium and water. Effective renal plasma flow, glomerular filtration rate, and renal clearance of lithium were studied in 67 stable non-diabetic RTx and 44 healthy controls. Forty-eight of the RTx were treated with CsA, prednisone, and azathioprine. Nineteen were treated exclusively with prednisone and azathioprine. In RTx with a good graft function (serum-creatinine <125 µmol/l), no specific CsA-induced renal haemodynamic and tubular dysfunctions were evident. In CsA-treated RTx with a slightly reduced renal function (serum creatinine 125–180 µmol/l) a decrease in fractional proximal tubular reabsorption was found. The renal clearances of urate and magnesium were comparable between RTx treated with or without CsA, and a significant correlation between glomerular filtration rate and renal clearance of urate was found. CsA-treated RTx had a significantly higher blood pressure, independent of glomerular filtration rate and segmental tubular function. In conclusion, at nadir CsA blood levels, no specific CsA-induced tubular dysfunction evaluated by the renal lithium clearance method could be demonstrated in RTx receiving chronically low-dose CsA. The hyperuricaemia commonly seen in RTx seems to be mainly caused by the reduced glomerular filtration rate. [ABSTRACT FROM AUTHOR]

To determine whether years since injury, level of injury, degree of injury, gender, or age influence renal function in 66 spinal cord injuries (SCI) patients without urological complications, individual kidney effective renal plasma flow (ERPF) and radionuclide renogram (RR) were measured using technetium-99m mercaptoacetyltriglycine (Tc-99m MAG3). The 176 individual kidneys included 84 kidneys with normal ERPF and RR, 48 kidneys with normal ERPF but abnormal RR, and 44 kidneys with abnormal ERPF and RR. The incidence of abnormal Tc-99m renal study results was higher in the kidneys of female patients (37/54, 68%) than of male patients (55/122, 45%) (p < 0.05). We found that Tc-99m MAG3 renal studies including ERPF and RR are safe and noninvasive urological screening tests for SCI patients.Copyright © 2000 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

In normal subjects recombinant human growth hormone (rhGH) increases glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) through the action of insulin-like growth factor-I (IGF-I). We have measured clearance of inulin and para-aminohippuric acid in 18 children with chronic renal failure (CRF) during their 1st year of rhGH treatment to look at the immediate (first 3 h), short-term (1 week) and long-term (1 year) effects of treatment. On day 1 mean (range) age was 9.1 (4.9-13.9) years, GFR 19 (9-58) and ERPF 77 (34-271) ml/min per 1.73 m. During treatment height velocity increased from 4.5 (1.7-6.5) to 9.5 (4.8-12.7) cm/year ( P<0.0001). Two children required dialysis after 0.75 years and 1 child was electively transplanted after 0.5 years. There were no other serious adverse events. GFR and ERPF were unchanged in the 3 h following rhGH. GFR remained constant on day 8, 22 (6-56) and after 1 year, 20 (9-59) ml/min per 1.73 m. ERPF increased to 96 (33-276) ml/min per 1.73 m on day 8 P=0.005), and remained elevated, but not significantly so, at 99 (24-428) ml/min per 1.73 m at 1 year. Fasting IGF-I increased from 147 (46-315) ng/ml to 291 (61-673) by day 8 P<0.003), and to 341 (101-786) ng/ml at 1 year. There was no correlation between the change in IGF-I and renal function. Blood pressure, albumin excretion and dietary protein intake were unchanged by treatment. The significance of increased ERPF after 1 week of rhGH in CRF is unclear, but long-term follow-up of renal function is indicated. [ABSTRACT FROM AUTHOR]

Renal haemodynamics and urinary protein excretion (UPE) were investigated in 36 patients with IgA nephropathy more than 3 years after renal biopsy (mean interval 6.3±0.5 years). At follow-up, 39% of patients had a reduced glornerular filtration rate (GFR) and 11% end-stage renal failure. Twenty-five percent had albuminuria, and a further 25% microalbuminuria. All albuminuric patients had GFRs below the mean, and 78% of the albuminurics had a reduced GFR. However, non-albuminurics also had decreased GFRs and GFR tended to fall with the duration of the disease in this group of patients. On comparing the histological changes in the biopsies with haemodynamic and UPE studies performed 6 years later, we found significant correlations between the extent of segmental glomerular sclerosis and GFR, effective renal plasma flow, urinary albumin and IgG excretion, respectively. Histological grading correlated with the same variables. Of the 4 uraemic patients, 2 were nephrotic at presentation, while the other 2 had a nephritic onset of disease and later developed heavy proteinuria. Three of their biopsies showed ≥10% segmental glomerulosclerosis. Juvenile IgA nephropathy is not a harmless disease. Our results indicate that these children should be carefully monitored with adequate GFR measurements and urine protein analyses. [ABSTRACT FROM AUTHOR]

The influence of metabolic control (HbA), noradrenaline (NA) and insulin-like growth factors (IGF-I and IGF-II) on renal function and size was investigated in 11 insulin-dependent diabetes mellitus patients aged 11-17 years. Renal function was evaluated in terms of glomerular filtration rate (GFR) and effective renal plasma flow (ERPF). Renal size was determined as renal parenchymal volume (RPV) by ultrasonography. The patients' HbA values ranged from 8.2% to 12.9% (normal range 5.5-8.5%) and their GFR and ERPF were higher than normal. Their IGF-II values were higher, and NA and IGF-I levels were lower than those of healthy controls. Inverse correlations between NA and GFR ( r=−0.66) and NA and ERPF ( r=−0.63) were found. No correlation was found between serum IGF-I and renal functional parameters. The IGF-II values correlated with GFR and HbA ( r=0.63, r=0.70 respectively). There were linear correlations between RPV and GFR, RPV and ERPF, HbA and GFR, and ERPF and RPV. Decreased NA concentrations and increased IGF-II values appear to be factors contributing to renal hyperfunction in these patients. [ABSTRACT FROM AUTHOR]

We compared the nephrotoxic interaction between cisplatin (CP) and amikacin (AM) in young and adult rats, using different dosage combinations. Following a single i.v. dose of CP, AM was administered s. c. for 14 days. The dose of CP was chosen to cause a 20%-50% fall in the glomerular filtration rate (GFR), while a dose of AM was chosen that had only a minimal effect on GFR. In adult rats, a decrease in GFR to 60% of the control value after CP alone was seriously aggravated by a non-toxic AM course given during 2 weeks after CP. In this combination, the GFR per 100 g body weight was reduced to 30% of control at week 2, which rose to 40% of control at week 15. In young rats, a non-toxic AM course did not aggravate the CP-induced impairment in GFR. However, when the dose of AM was increased to cause a 20% reduction in the GFR, the nephrotoxicity was potentiated. When measured at week 2, the GFR per 100 g body weight was 40% of control after the combined treatment compared with 80% of control after CP alone. As in adult rats, there was only a partial recovery of the GFR. In conclusion, in both adult and young rats, a course of AM following a single injection of CP potentiated CP-induced nephrotoxicity. [ABSTRACT FROM AUTHOR]

One hundred children aged 1.5-19.5 years, with recurrent urinary tract infections, at least one of which was febrile (pyelonephritis, PN), were investigated by means of inulin and para-aminohippurate (PAH) clearance tests for the evaluation of glomerular filtration rate (GFR), effective renal plasma flow, and concentrating and diluting capacities. Renal function data were collated with the clinical history and radiological findings. GFR and PAH clearance were found to be reduced compared with controls. Patients whose first PN was diagnosed before the age of 3 - particularly those with a history of three or more PN infections - showed the lowest values for GFR and PAH clearance. Furthermore, parenchymally reduced kidneys were found most frequently in this group of patients. Concentrating capacity was decreased in some patients, but a low concentrating capacity did not reveal patients with reduced GFRs. Diluting capacity evaluated as minimal urine osmolality was normal, but was reduced when evaluated as free water clearance in some patients with reduced values for GFR. [ABSTRACT FROM AUTHOR]

Recently renewed interest has been focused on constant infusion clearance to assess GFR accurately. In this study we compared GFR and ERPF calculated from the constant infusion method (CIM = I × V/P) with that calculated from the standard method (StM = U×V/P), in 100 patients with renal disease who were subdivided in four groups according to their GFR-StM (<30;30–60; 60–90; >90 ml/min). After a priming dose, a constant infusion of I-iothalamate (=GFR) and I-hippurate (=ERPF) was started at 9 a.m. The infusion rates were individually adjusted to the GFR which was approximated from the serum creatinine concentration. After a 90-min equilibration period, GFR-StM and ERPF-StM were determined for two 2-h periods. These values were compared with GFR-CIM and ERPF-CIM calculated from the plasma concentration of the respective tracers at the end of each 2-h period (=210 and 330 min). In the patient group with GFR-StM <30 ml/min, the I-iothalamate plasma concentration increased progressively over time. Consequently, average GFR-CIM at 210 min (34.2, SE±2.1 ml/min) was higher than the GFR-CIM at 330 min (31.9, SE±2.0 ml/min; <0.001). In addition both values were significantly higher than the corresponding GFR-StM values (18.1±2.4 and 15.3 ± 1.6 ml/min respectively). In the two patient groups with GFR-StM > 60 ml/min, the I-iothalamate plasma concentration decreased progressively over time. Consequently in both groups GFR-CIM at 210 min was significantly lower than GFR-CIM at 330 min. In all groups the I-hippurate plasma concentrations were constant during the second 2-h period. Because constant plasma concentrations of I-iothalamate are not obtained during a 330 min period and GFR-CIM overestimates GFR-StM in patients with low GFRs, we conclude that the constant infusion technique is not a valid method to assess GFR accurately if renal function is impaired. [ABSTRACT FROM PUBLISHER]

The nephrotoxicity of cyclosporin (CsA) continues to be a clinical problem that detracts from its obvious benefits as an immunosuppressive agent. Animal models designed to study the problem have generally relied either on chronic administration of high doses of the drug or acute administration of single i.v. doses. The present study establishes a model of CsA nephrotoxicity using doses of the drug comparable to those used in man administered over a time period sufficient for haemodynamic and structural changes to become evident. The technique used measures glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) by the plasma clearance of chromium EDTA and iodohippuran respectively. This has the advantage of allowing sequential measurements in individual animals. Significant impairment of GFR was seen in animals treated intraperitoneally with doses of CsA as low as 5 mg/kg/day. CsA 7.5 mg/kg/day caused a significant reduction in ERPF, and at 10 mg/kg/day and greater filtration fraction also declined significantly. Detailed histological examination of the kidneys from these animals also revealed significant tubular dilatation at 10 mg/kg/day and above. This model of CsA toxicity circumvents many of the problems associated with other models. The animals can be studied longitudinally and the period of administration has relevance to clinic practice. This work provides the basis for further studies which can closely mimic the clinical situation using doses similar to those used for human maintenance immunosuppression. [ABSTRACT FROM PUBLISHER]

Technetium-99m L,l-ethylenedicysteine (Tc L,l-EC) is a new renal tubular tracer that allows the determination of the effective renal plasma flow (ERPF). The aim of this study was to derive simplified methods for the estimation ofTc- L,l-EC clearance using one or two plasma samples after bolus injection. Fifty-nine multiple plasma dual-tracer samples (nine samples from 5 to 120 min after injection) were obtained after injection of kit-formulatedTc- L,l-EC and iodine-125 orthoiodohippurate (01H). The studies were performed in 25 stable and 24 unstable transplant recipients, in five patients with renal insufficiency (four on chronic haemodialysis) and in five normal volunteers. This allowed a wide range of renal function values to be covered, with ERPF (estimated by 01H clearance) ranging from 25.4 to 604.0 ml/min. The referenceTc- L,l-EC clearance, as calculated from the multisample model, could be estimated from two samples at 15 and 90 min with an error of 11.3 ml/min and from one sample at 90 min with an error of 17.8 ml/min. Using appropriate linear regression analysis, ERPF could be estimated by the two- and one sampleTc- L,l-EC clearance with an error of 24.2 and 22.8 ml/min, respectively. In conclusion,Tc- L,l-EC clearance can be accurately estimated by simplified one or two-sample methods. Moreover, these methods can be used to estimate ERPF with an error that remains acceptable for clinical purposes. [ABSTRACT FROM AUTHOR]

Gamma camera-based clearance techniques which use the renal uptake ratio (RUR) of the radiotracer are available to estimate the effective renal plasma flow (ERPF) and glomerular filtration rate. To evaluate the accuracy of these techniques, we measured RUR by an optimized procedure and compared it with standard ER-PF. Iodine-123 orthoiodohippurate (OIH) scintigraphy and simultaneous para-aminohippurate clearance study for measuring standard ERPF were performed in three hospitals in 24 patients with normal or mildly impaired renal function. 1231-OIH was injected intravenously and 10-s consecutive imaging of the kidneys was started when the abdominal aorta was seen. The attenuation coefficient for 1231 was measured in each hospital using the same water-equivalent absorption materials and used for the attenuation correction. After subtracting background radioactivity, RURs were defined as the count ratios of fractional renal uptakes based on the integral from 1 to 2, 2 to 3, 1.5 to 2.5 and 1 to 3 min after the injection of 1231-OIH in relation to injected doses using the following three procedures in respect of attenuation correction: (1) RUR without attenuation correction, (2) RUR with fractional renal uptake corrected by the measured attenuation coefficient, (3) RUR with the total injected dose corrected by the absorption material. To decide upon the appropriate correction method and time interval, RURs were compared with standard ERPF. Among the three correction methods, procedure 2 showed the highest correlation between RUR and standard ERPF, but the correlation coefficient was low (r=0.75). No significant difference was observed among the RURs of each time interval. Individual kidney function measured from early renal uptake may be inaccurate even when appropriate correction is made for attenuation, background activity or time lag between injection and data acquisition. Gamma camera-based measurement of renal function usingI-OIH is limited with regard to accuracy and reproducibility, though it is convenient and non-invasive. [ABSTRACT FROM AUTHOR]

For many years iodide-131 Hippuran has been used as a tracer to measure effective renal plasma flow (ERPF). Because of the low renal clearance of free-Iiodide and the inability to count it separately fromI-Hippuran, freeI-iodide will lower the calculatedI-Hippuran clearance, resulting in a lower estimated ERPF. This study was performed to establish the maximum allowable radiochemical impurity of freeI-iodide inI-Hippuran preparations for ERPF measurements in continuous clearance studies. A known amount ofI-iodide was added to the (I-iodide-free)I-Hippuran solution used for continuous infusion clearance studies in nine patients.I-iodide activity was used because it can be counted separately fromI-Hippuran in the infusion solutions and plasma samples while it behaves exactly likeI-iodide, so that the results obtained withI-iodide can be extrapolated toI-iodide. After performing the clearance studies, the ERPF was calculated firstly withI-Hippuran activity only (=true ERPF) and secondly including the free radioactive iodide activity (=false ERPF) in the clearance formula. As expected, if freeI-iodide is present in the infusion solution, its concentration in plasma will be highest at the end of the clearance study. TheI-iodide concentration in plasma relative to theI-Hippuran concentration will be higher in patients with high ERPF values.I-iodide in the infusion solution causes a fall in the ERPF as measured by the continuous infusion technique: 0.5%, 1% and 2% of freeI-iodide in the infusion solution result in a reduction in ERPF of about 1.5%, 3.5% and 7% respectively after 1.5 h and of 3.5%, 6.5% and 13% respectively after 5.5 h if ERPF is high. It is concluded that a maximum of 0.5% of freeI-iodide inI-Hippuran preparations is permissible if ERPF is to be measured with an error of less than 5%. [ABSTRACT FROM AUTHOR]

Recent studies have shown that technetium 99m mercaptoacetyltriglycine (MAG-3) is a suitable replacement for iodine 131 or 123 hippurate in gammacamera renography. Also, the determination of its clearance is of value, since it correlates well with that of hippurate and thus may be an indirect measure of renal plasma flow. In order to simplify the clearance method we developed formulas for the estimation of plasma clearance of MAG-3 based on a single plasma sample and compared them with the multiple sample method based on 7 plasma samples. The correlation to effective renal plasma flow (ERPF) (according to Tauxe's method, using iodine 123 hippurate), which ranged from 75 to 654 ml/min per 1.73 m, was determined in these patients. Using the developed regression equations the error of estimate for the simplified clearance method was acceptably low (18-14 ml/min), when the single plasma sample was taken 44-64 min post-injection. Formulas for different sampling times at 44, 48, 52, 56, 60 and 64 min are given, and we recommend 60 min as optimal, with an error of estimate of 15.5 ml/min. The correlation between the MAG-3 clearances and ERPF was high ( r = 0.90). Since normal values for MAG-3 clearance are not yet available, transformation to estimated ERPF values by the regression equation (ERPF=1.86 × C + 4.6) could be of clinical value in order to compare it with the normal values for ERPF given in the literature. [ABSTRACT FROM AUTHOR]

Animal studies have suggested that Tc-mercapto-acetylglycyl-glycyl-glycine (Tc-MAG3) might be suitable for the determination of the renal plasma flow (RPF) because of its high renal clearance. In this study I-orthoiodohippurate (I-OIH) and Tc-MAG3 (labeling always >95%) were administered simultaneously in 11 patients (creatinine clearance ranging from 14 to 130 ml/min per 1.73 m) to measure effective RPF(ERPF) using the standard technique (UV/P). Glomerular filtration rate (GFR; clearance of I-thalamate, I-OT) was also measured. The mean ratio of Tc-MAG3 clearance to I-IOH clearance was 0.55±0.02 (SEM), P<0.01, n=16, and was independant of GFR and ERPF. To study this difference in renal handling ofthe radiopharmaceuticals, renal extractions by the right kidney were determined in another six patients after a single shot of the agents. Renal extraction of Tc-MAG3 was 0.60±0.03 after 5 min, and 0.41±0.08 after 30 min. Renal extraction of I-OIH amounted to 0.86±0.04 and 0.77±0.03, respectively. Using renal extractions of 0.41 and 0.77, respectively, it appeared that calculated renal plasma flows measured simultaneously with Tc-MAG3 and I-OIH were similar. Protein binding 30 min after the priming dose was 66% for Tc-MAG3 and 47% for I-OIH. We conclude that in spite of a high renal clearance (ratio to I-OT clearance 2.69±0.27), Tc-MAG3 seems unsuitable for an accurate determination of the RPF. This conclusion is strongly supported bythe observation that the ratio of Tc-MAG3 to I-IOH clearance markedly decreased from 0.66 to 0.32 in a patient with an increase in urinary protein loss. [ABSTRACT FROM AUTHOR]

Methods of effective renal plasma flow measurement by I-orthoiodohippurate elimination and para-aminohippurate clearance were compared with and without captopril pretreatment in 10 chronic heart failure patients and in 20 patients after transmural myocardial infarction. In the chronic heart failure group measurements of effective renal plasma flow by the two techniques were strongly correlated (r=0·92, <0·00001), as was the captopril-mediated change in effective renal plasma flow by the two methods (r=0·85, =0·002). However, in absolute terms para-aminohippurate clearance significantly exceeded I-orthoiodohippurate clearance by a mean (± SD) of 24·8 ± 43·7 ml. min (<0·05) so that only using the former technique was a signifincant in renal perfusion observed in response to converting enzyme inhibition. In the post-myocardial infarction group, correlations between the two methods were variable and much poorer than in the chronic heart failure group (r=0·54, =0·01 and r=0·74, =0·002 on consecutive days). Furthermore, captoprilmediated increments in effective renal plasma flow by the two techniques were unrelated (r= − 0·19, =0·59). In this group I-orthoiodohippurate elimination significantly exceeded para-aminohippurate clearance (<0·05). This reversed association and the weaker relationships between methods in post-infarction as compared to chronic heart failure patients may be related to interference by thrombolytic or aspirin treatments. [ABSTRACT FROM PUBLISHER]

Quantitation of renal function may be performed with a variety of radiopharmaceuticals which reflect slightly different renal functions. Plasma sampling techniques and imaging techniques have been used to derive absolute measurements of renal function. The addition of imaging permits the determination of relative or 'split' function. Time-activity curves from renal studies provide other quantitative parameters of function reflecting arterial supply, renal cortical function, and patency of the renal collecting system. Quantitative radionuclide studies of the kidneys provide comprehensive, reproducible, and objective assessments of renal function. [ABSTRACT FROM AUTHOR]

It is well known that patients with Type 1 (insulin-dependent) diabetes exhibit both increased glomerular filtration rate and effective renal plasma flow, which can be found even when these patients are well controlled. Usually this is attributed to a decrease in renal vascular resistance and/or to enlarged kidney size and glomerular volume. Among the factors which govern glomerular filtration rate, renal plasma flow is most important. Renal plasma flow increases if renal vascular resistance decreases. The latter might exist in insulin-dependent diabetes mellitus because of either a predominantly afferent or a predominantly efferent vasodilatation. Dopamine is an agent which causes predominantly efferent vasodilatation. Therefore, the effects of infusing a low dose of dopamine on glomerular filtration rate and effective renal plasma flow in 12 well-controlled patients with Type I (insulin-dependent) diabetes and 28 healthy volunteers were compared to investigate whether the increased glomerular filtration rate in Type 1 diabetes is caused by an efferent vasodilatation. The median increase in glomerular filtration rate during dopamine infusion amounted to 13.0% in diabetic patients and 12.5% in healthy control subjects (n. s.). It is concluded that the elevated glomerular filtration rate in well-controlled Type 1 diabetes is not caused by a predominantly efferent vasodilatation. [ABSTRACT FROM AUTHOR]

Simple Summary: The aim of this study was to investigate the simultaneous measurement of two different renal markers (iohexol and p-aminohippuric acid) in the plasma of different poultry species as the gold standard method. The two markers reflect three different renal processes: glomerular filtration, effective renal plasma flow, and tubular secretion. The rate at which the kidneys filter blood is called the glomerular filtration rate. The effective renal plasma flow is the volume of plasma that reaches the kidney per time unit. Tubular secretion can be defined as active transport from the peritubular capillaries to the renal tubules. A moderate correlation was observed between tubular secretion and the glomerular filtration rate. A good correlation was demonstrated between the effective renal plasma flow and the glomerular filtration rate. This might be useful to model both renal processes. This approach could support the further development and validation of clinical renal biomarkers. These markers can be useful in the case of a chronic renal disease or renal failure, for which repeated evaluations of the renal function are required. The aim of the current study was to investigate the simultaneous measurement of plasma p-aminohippuric acid (PAH) clearance as a potential marker to assess effective renal plasma flow (eRPF) and tubular secretion (TS), and the plasma clearance of iohexol (IOH) as a marker of the glomerular filtration rate in poultry species. The PAH was administered intravenously (IV) to broiler chickens, layers, turkeys, Muscovy ducks, and pigeons. Each animal received successively a single bolus dose of 10 mg PAH/kg bodyweight (BW) and 100 mg PAH/kg BW to assess the eRPF and TS, respectively. Simultaneously with both PAH administrations, a single IV bolus of 64.7 mg/kg BW of IOH was administered. A high linear correlation (R2 = 0.79) between eRPF, based on the clearance of the low dose of PAH, and BW was observed for the poultry species. The correlation between TS, based on the clearance of the high dose of PAH, and BW was moderate (R2 = 0.50). Finally, a moderate correlation (R2 = 0.68) was demonstrated between GFR and eRPF and between GFR and TS (R2 = 0.56). This presented pharmacokinetic approach of the simultaneous administration of IOH and PAH enabled a simultaneous evaluation of eRPF/TS and GFR, respectively, in different poultry species. [ABSTRACT FROM AUTHOR]

Aims This study examined the 131 I-hippuran extraction fraction during baseline renal blood flow rates and at high flow rates induced by dopamine. Methods In 12 healthy subjects, arterial and renal venous sampling was used to measure the renal extraction of 131 I-hippuran. Effective renal plasma flow values determined by the urinary clearance of 131 I-hippuran were compared with renal plasma flow values corrected for incomplete extraction of 131 I-hippuran. Results Dopamine (3 µg kg-1 min-1 ) decreased 131 I-hippuran extraction from 75 ± 4% at baseline to 62 ± 6% (means ± 95% confidence intervals, P < 0.001). Hence, the increase in renal plasma flow (85 ± 23%) greatly exceeded the rise in effective renal plasma flow (51 ± 15%, P < 0.002). Conclusions Dopamine induced increases in renal blood flow are largely under­estimated when measurements are not corrected for incomplete extraction of 131 I-hippuran. [ABSTRACT FROM AUTHOR]

To evaluate effective renal plasma flow (ERPF) we performed renal scintigraphies with 99mTc-Mercaptoacetyl-triglycine (MAG3) in nine patients with glycogen storage disease I (GSD I) (age: 16 +/- 7 years). Two patients presented with proteinuria, none showed hyperaminoaciduria, disturbed tubular reabsorption of phosphate or hypertension. 99mTc-MAG3 clearance values were elevated in eight out of nine patients (865 +/- 233 ml/min/1.73 m2 body surface area) and exceeded the age-dependent mean values by 21%-145%. ERPF values in patients with poor metabolic control were higher than in patients with long-term good metabolic control (988 +/- 186 vs. 619 +/- 55 ml/min/1.73 m2; P < 0.05). We conclude that enhanced ERPF is a common finding in GSD I patients, which precedes clinically overt nephropathy. Renal scintigraphy with 99mTc MAG3 is a suitable method for the early detection and monitoring of kidney dysfunction in GSD I. [ABSTRACT FROM AUTHOR]

Objective: To determine the ability of renal contrast‐enhanced ultrasonography (CEUS) to detect acute drug‐induced changes in renal perfusion (using the glucagon‐like peptide (GLP)‐1 receptor agonist exenatide and nitric oxide [NO]‐synthase inhibitor L‐NG‐monomethyl arginine [l‐NMMA]), and assess its correlation with gold standard‐measured effective renal plasma flow in humans. Methods: In this prespecified exploratory analysis of a placebo‐controlled cross‐over study, renal hemodynamics was assessed in 10 healthy overweight males (aged 20‐27 years; BMI 26‐31 kg/m2) over two separate testing days; during placebo (isotonic saline) and subsequent exenatide infusion (Day‐A), and during l‐NMMA, and subsequent exenatide plus l‐NMMA infusion (Day‐B). Renal cortical microvascular blood flow was estimated following microbubble infusion and CEUS destruction‐refilling‐sequences. Renal cortical microvascular blood flow was compared with simultaneously measured effective renal plasma flow in humans, derived from para‐aminohippuric acid‐clearance methodology. Results: On Day‐A, effective renal plasma flow increased by 68 [26‐197] mL/min/1.73 m2 during exenatide vs placebo infusion (+17%; P = .015). In parallel, exenatide increased renal cortical microvascular blood flow, from 2.42 × 10−4 [6.54 × 10−5‐4.66 × 10−4] AU to 4.65 × 10−4 [2.96 × 10−4‐7.74 × 10−4] AU (+92%; P = .027). On Day‐B, effective renal plasma flow and renal cortical microvascular blood flow were reduced by l‐NMMA, with no significant effect of concomitant exenatide on renal hemodynamic‐indices assessed by either technique. Effective renal plasma flow correlated with renal cortical microvascular blood flow on Day‐A (r = .533; P = .027); no correlation was found on Day‐B. Conclusions: Contrast‐enhanced ultrasonography can detect acute drug‐induced changes human renal hemodynamics. CEUS‐assessed renal cortical microvascular blood flow moderately associates with effective renal plasma flow, particularly when perfusion is in normal‐to‐high range. Renal CEUS cannot replace effective renal plasma flow measurements, but may be a complementary tool to characterize regional kidney perfusion. [ABSTRACT FROM AUTHOR]

Background: A method was developed to assess the kidney parameters glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) from 2-deoxy-2-[18F]fluoro-d-glucose (FDG) concentration behavior in kidneys, measured with positron emission tomography (PET) scans.Twenty-four healthy adult subjects prospectively underwent dynamic simultaneous PET/magnetic resonance imaging (MRI) examination. Time activity curves (TACs) were obtained from the dynamic PET series, with the guidance of MR information. Patlak analysis was performed to determine the GFR, and based on integrals, ERPF was calculated. Results were compared to intra-individually obtained reference values determined from venous blood samples.Results: Total kidney GFR and ERPF as estimated by dynamic PET/MRI were highly correlated to their reference values (r = 0.88/p < 0.0001 and r = 0.82/p < 0.0001, respectively) with no significant difference between their means.Conclusions: The study is a proof of concept that GFR and ERPF can be assessed with dynamic FDG PET/MRI scans in healthy kidneys. This has advantages for patients getting a routine scan, where additional examinations for kidney function estimation could be avoided. Further studies are required for transferring this PET/MRI method to PET/CT applications. [ABSTRACT FROM AUTHOR]

Low i.v. doses of cadmium chloride (15 μg Cd) given to pullets resulted in a significant reduction in urine flow (UF), glomerular filtration rate (GFR) and effective renal plasma flow (ERPF). However, in hens treated with the heavy metal chelate FeNa EDTA prior to cadmium treatment no oliguria or reduction in GFR or ERPF was observed. It is suggested that the renal changes following the i. v. administration of cadmium to diuretic hens and alleviated in hens primed with the heavy metal chelate may result from changes in glomerular hemodynamics. [ABSTRACT FROM AUTHOR]