Measurement of cystatin-C and creatinine in urine.
ABSTRACT The concentration of serum cystatin-C (Cys-C) is highly correlated with creatinine (Cr), and is mainly determined by glomerular filtration; thus, Cys-C may be an index of the glomerular filtration rate (GFR). However, the kinetics of urinary Cys-C and Cr excretions are unclear. Thus, we investigated the kinetics of urinary Cys-C and Cr excretions, and examined whether the urinary Cys-C concentration can be used as a marker of renal function.
The urinary excretion of Cys-C and Cr was evaluated in 1670 healthy subjects and 217 patients with proteinuria. We also investigated the urinary Cys-C concentration in 52 patients with chronic renal failure.
There was a good correlation between the urinary concentrations of Cys-C and Cr in the healthy group. This relation was also observed in patients showing persistent proteinuria without tubular cell damage. The mean urinary Cr concentration increased with age, and it was affected by the muscle mass. In contrast, the urinary Cys-C concentration was not affected by the muscle mass, and the concentration remained constant for all ages. We further found that the ratio of Cys-C to Cr (CCR) is a good index of the state of Cys-C reabsorption in the proximal tubules.
The urinary CCR can be a marker of renal tubular dysfunction. In addition, when CCR was in the normal range, the urinary Cys-C concentration accurately reflected the glomerular filtration function.
- SourceAvailable from: Ragaa H M Salama[Show abstract] [Hide abstract]
ABSTRACT: To investigate the role of bone morphogenetic protein-2 (BMP-2) in patients with urinary tract infection (UTI) and renal stone in relation to Tamm-Horsfall protein (THP) and osteopontin (OPN). ELISA kits were used to determine these markers in serum and urinary samples of 20 patients with UTI, 15 with renal stone and 10 controls. BMP-2 significantly increased in serum of patients who had UTI (P=0.05) and renal stone (P=0.01). In the case of UTI, serum BMP-2 at cutoff 44 pg/mL had sensitivity and specificity (92%, 80%), while cystatin C at cutoff 525 ng/mL showed sensitivity and specificity (85%, 91%). THP is a good predictor of renal diseases (P<0.001) by regression analysis. It is also the most sensitive urinary marker for UTI with sensitivity and specificity (94%, 75%) at cutoff 305 ng/mL. Combination of serum BMP-2 and cystatin C are more sensitive and accurate for early diagnosis of renal infection and damage.Clinical biochemistry 04/2012; 45(10-11):766-9. DOI:10.1016/j.clinbiochem.2012.04.005 · 2.23 Impact Factor
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ABSTRACT: Urinary cystatin C has been reported to be a good marker for tubular damage and acute kidney injury. The aim of this study was to develop a high throughput assay for the quantification of urine cystatin C. Antigen-excess, imprecision, interference, linearity, recovery, sample stability and reference values were evaluated on Cobas c501. The assay was linear over the dynamic range of the study (R²=0.9994). The total assay imprecision was below 5%. The assay recovery was estimated at 87-100%. No tendency to antigen-excess (up to 35 mg/L), nor interference with haemoglobin (1.25-10 g/L) was observed. Cystatin C was stable for 1 day at ambient temperature (19-23°C) but for 2 days at +4°C. The reference interval for cystatin C in urine was <0.414 mg/L. The urinary cystatin C assay verified to be a reliable assay with convenient performance characteristics, enabling routine testing on clinical chemistry platforms.Clinical biochemistry 03/2012; 45(4-5):339-44. DOI:10.1016/j.clinbiochem.2011.12.027 · 2.23 Impact Factor