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Study Design: Prospective cohort study., Objectives: To investigate the relationship between (51)chromium-ethylene-diamine-tetra-acetate ((51)Cr-EDTA) clearance, serum cystatin C (CysC), serum creatinine, creatinine clearance and estimated glomerular filtration rate (eGFR(MDRD), MDRD stands for modification of diet in renal disease) based on the serum creatinine in patients with complete or incomplete spinal cord injury (SCI) and to develop and evaluate a GFR-estimating equation using serum CysC., Settings: Spinal Cord Injury Unit, Viborg Regional Hospital, Viborg, Denmark., Methods: Ninety-eight men and 47 women with SCI were included in the study. Serum CysC levels were measured by an automated particle-enhanced nephelometric immunoassay, serum and urine creatinine levels were measured by an enzymatic method traceable to the IDMS creatinine reference method, and (51)Cr-EDTA clearance was measured by a multiple plasma sample method., Results: The area under the curves (AUCs) in the non-parametric receiver operating characteristics (ROC) plots for serum CysC were compared with serum creatinine and to eGFR(MDRD) and revealed a significant difference (P-value < 0.05) for all SCI patients. There was no significant difference between the AUC for serum CysC compared with the AUC for creatinine clearance. GFR (ml min(-1) per 1.73 m(2)) can be calculated from serum CysC values (mg l(-1)) using the equation eGFR(CysC) = 212·exp(0.914·CysC). The model accurately predicted the GFR of 88% of patients within ± 30% of the measured GFR, and it was able to predict the GFR of 50% of patients within ± 10% of the measured GFR., Conclusion: In patients with SCI, GFR can be estimated independent of age, sex and muscle mass by a newly developed equation based on a single serum CysC value.

Unlabelled: Hepatocyte growth factor (HGF) is a growth-promoting peptide that appears to act in a renotropic and nephroprotective manner during acute renal damage. Recent studies suggest that HGF is also of importance in chronic renal diseases. The serum HGF level is correlated with serum creatinine, and it has been suggested that glomerular and tubular diseases affect serum HGF differently. In the present study. levels of serum HGF were determined and correlated to glomerular filtration rate (GFR) in 118 patients with various chronic renal diseases. GFR was determined by 99mTc-DTPA clearance, and the GFR values were evenly distributed in the interval 5-155 mL/min/1.73 m2. Serum HGF levels increased slightly with decreasing GFR: the Pearson correlation coefficient being 0.49 (p<0.0001). In 21 additional patients with end-stage renal disease treated with continuous ambulatory peritoneal dialysis, there was a more marked increase in the serum levels of HGF. The effect of glomerular and tubular diseases on serum HGF was examined by comparing the HGF levels in two groups of patients with similar GFR values: 57 patients with mainly glomerular disorders (diabetic nephropathy with micro- or macroalbuminuria or glomerulonephritis) and 14 patients with mainly tubular disorders (polycystic kidney disease). There was no significant difference between the HGF levels of the two groups (p=0.30)., In Conclusion: Serum HGF levels are correlated with GFR (for GFR > or = 5 mL/min/1.73 m2) in patients with chronic renal diseases, and glomerular and tubular disorders seem to affect the HGF level similarly.

Cystatin C is a low molecular weight protein and the plasma level of cystatin C is mainly determined by glomerular filtration, making cystatin C an endogenous marker of glomerular filtration rate. The aim of the study was to elucidate the applicability of plasma cystatin C as a marker of renal function in patients with liver cirrhosis. Serum cystatin C and creatinine concentrations were compared with creatinine clearance. Thirty-six patients (14 females and 22 males aged between 33 and 81 years) with liver cirrhosis with normal to severely impaired kidney function were included. Plasma cystatin C was measured by an automated particle-enhanced nephelometric immunoassay (Dade Behring Diagnostics) and plasma creatinine by an enzymatic method. Plasma levels of cystatin C and creatinine were found to increase with decreasing values of creatinine clearance. The reciprocal values of cystatin C and creatinine were compared with those for creatinine clearance revealing an r[sup 2] of 0.37 and 0.18, respectively. Comparison of the areas under the curves (AUC ) of the non-parametric receiver-operating characteristic plots for plasma cystatin C (AUC = 0.7364; SE = 0.0929) and plasma creatinine (AUC = 0.6309; SE = 0.1028) revealed a significant difference between plasma cystatin C and plasma levels of creatinine (p-value = 0.03). The results demonstrate that the diagnostic accuracy of plasma cystatin C was better than plasma creatinine in identifying liver cirrhotic patients with reduced glomerular filtration rate. [ABSTRACT FROM AUTHOR]

The Dade Behring N Latex Cystatin C assay, a particle-enhanced nephelometric immunoassay for measuring serum cystatin C, was evaluated on the Dade Behring Nephelometer II. The assay time was 6 min and the throughput was 75 samples per hour. The sample volume was 40 μL and the measuring range was 0.25-7.90 mg/L. Imprecision studies revealed within-run CVs <1.8% and between-run CVs <1.8% in the concentration range 0.87-4.63 mg/L. Recovery was 92.4-101.3%. Linearity studies showed excellent correlation between the theoretical and obtained values. No interferences were detected from haemoglobin <1.0 mmol/L, bilirubin <512 μmol/L and Intralipid® <20 g/L. Stability of cystatin C in serum was 7 days at temperatures from 20°C to -20°C and 6 months at -80°C. Measurements of cystatin C in heparin-plasma and EDTA-plasma did not differ significantly from cystatin C measured in serum. Fifty patient samples run on the Dade Behring Nephelometer II (y) were compared to the Dako Cystatin C assay (x). The Passing-Bablok regression analysis revealed y=1.105x-0.340. In conclusion, the Dade Behring N Latex Cystatin C assay was precise and correlated with the Dako Cystatin C assay. [ABSTRACT FROM AUTHOR]

The protease inhibitor cystatin C is a non-glycosylated low molecular weight protein (M[sub r]=13359) which is produced by all nucleated cells at a constant rate, freely filtered by the renal glomeruli, and catabolized in the tubuli. The aim of the study was to elucidate the applicability of serum cystatin C as a marker of glomerular filtration rate (GFR) in patients with various kidney diseases with a wide range of renal function and in dialysis patients. Seventy-six patients with various kidney diseases (aged 20 to 79 years) and 61 dialysis patients (aged 21 to 82 years) were included. Serum cystatin C was measured by automated particle-enhanced immunoturbidimetry, serum and urine creatinine by an enzymatic method, and GFR by [sup 99m]Tc-DTPA-clearance using a single plasma sample method. Serum cystatin C in patients with various kidney diseases was 1.90±0.98 mg/L (mean±SD) and in dialysis patients 7.14±1.91 mg/L. In the non-dialysis patients a linear relationship was found between [sup 99m]Tc-DTPA-clearance and 1/serum cystatin C (r=0.91, p-value<0.0001), 1/serum creatinine (r=0.89, p-value<0.0001), and creatinine-clearance (r=0.88, p-value<0.0001). Comparison of the non-parametric ROC plots for serum cystatin C (area under the curve (AUC)=0.9665; SE=0.0169), serum creatinine (AUC=0.9554; SE=0.0205), and creatinine-clearance (AUC=0.9731; SE=0.0160) revealed no significant differences (p-values: 0.50, 0.78, and 0.49). In conclusion, cystatin C may be a likewise good marker of the GFR as serum creatinine and creatinine-clearance, cystatin C having the advantage being independent of gender and muscle mass. [ABSTRACT FROM AUTHOR]