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]

Abstract 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.

Objectives: Renal scintigraphy is widely used to evaluate residual function of a transplanted kidney from the donor. Dynamic computed tomography (CT) imaging can evaluate both kidney morphology and regional renal function. The aim of this study was to develop an imaging protocol and a calculation method using dynamic CT for assessing the effective renal plasma flow (ERPF) by model analysis, and to evaluate the validity of the obtained ERPF values. Methods: Preoperative dynamic CT examination with a low radiation dose exposure system was performed for 25 renal transplant donors, and ERPF was calculated from the obtained images (CT-ERPF). To calculate CT-ERPF, we set the region of interest (ROI) in the renal cortex using automatic ROI-setting software developed in our laboratory. We compared the processing time with automatic and manual ROI settings. To evaluate the validity of CT-ERPF, we examined the correlation of age with CT-ERPF and compared with reported ERPF values. We also compared the uptake rates of technetium-99m-dimercaptosuccinic acid and CT-ERPF in terms of the right-to-left ratio. Results: There was good agreement of CT-ERPF assessed using automatic and manual ROIs. CT-ERPF was negatively correlated with age and showed values below the reference ERPF range in 21 cases. The right-to-left ratio of CT-ERPF showed a significant correlation with that of technetium-99m-dimercaptosuccinic acid. Conclusions: Using our method, CT-ERPF was a useful indicator for preoperative evaluation of donor’s renal function.

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.

The literature review examines the historical aspects and key issues of the clinical application of new radiopharmaceuticals (RF) for positron emission tomography (PET). The gold standard for measuring effective renal plasma flow is p-[18F] fluorohippurate ([18F] PFH) due to its structure close to p-aminoimpurate one. [18F] FDS is a new potential tracer for the diagnosis of acute renal failure. PET tracers Re (CO) 3 ([18F] FEDA) and [18F] PFH are effective as surrogate markers for the selection of patients for endoradiotherapy with a potential nephrotoxic profile, in patients with hematopoietic malignant tumours and prostate cancer. PET imaging of the kidneys and urinary system can be of additional importance in difficult clinical situations and provide effective support in making diagnostic decisions, in particular in paediatric patients. Further scientific diagnostic research should focus on the synthesis of new radiopharmaceuticals that will have ideal properties for renal functional imaging, low binding to plasma proteins, high metabolic stability and low hepatobiliary clearance.

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]

Background and Hypothesis: Volenrelaxin, is a half-life-extended recombinant human relaxin protein developed for improving kidney perfusion and cardiorenal function. This study assessed the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of volenrelaxin following single- and multiple-ascending doses (SAD and MAD) administration., Methods: In this Phase 1, 4-part, randomized, double-blinded, placebo-controlled SAD and MAD study in healthy participants, SAD participants (n = 56) received an intravenous (IV) or subcutaneous (SC) dose of volenrelaxin or placebo in a dose-ascending manner. MAD participants (n = 77) received volenrelaxin or placebo SC once weekly for 5 weeks. Effective renal plasma flow (ERPF) and measured glomerular filtration rate (mGFR) were determined by para-aminohippurate and iohexol clearance, respectively., Results: Volenrelaxin demonstrated an extended half-life and increased acute and chronic placebo-adjusted ERPF change from baseline by 50% and 44%, respectively (p < 0.0001). Measured GFR was unchanged, while filtration fraction and afferent/efferent renal arteriolar resistances were reduced. Systolic and diastolic blood pressures decreased, and pulse rate increased with increasing volenrelaxin exposures, demonstrating maximal model-derived placebo-adjusted changes (90% confidence interval) of -6.16 (-8.04, -4.28) mmHg, -6.10 (-7.61, -4.58) mmHg, and + 4.39 (3.38, 5.39) bpm, respectively. Adverse events were mild, with no difference in orthostatic hypotension between volenrelaxin and placebo., Conclusion: Volenrelaxin was well-tolerated, safe and suitable for weekly SC dosing. Volenrelaxin showed a sustained improvement in kidney perfusion upon repeated dosing, supporting further clinical development in chronic kidney disease and chronic heart failure. Clinical trial registration: NCT04768855., (© The Author(s) 2024. Published by Oxford University Press on behalf of the ERA.)

Abstract 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 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

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.)

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.

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/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.