Urinary clusterin concentrations--a possible marker of nephropathy? Pilot study.

BACKGROUND Clusterin is a glycoprotein which participates in a number of pathophysiological processes in the organism. Information about clusterin use in the diagnosis of nephropathy and the differential diagnosis of proteinuria has been published recently. AIM Search for correlations between urinary clusterin concentration and other renal function markers. Evaluation of urinary clusterin measurement use in the differential diagnosis of nephropathy. METHODS Urea, creatinine, IgG, transferin, Na, K in serum and 24-hour collected urine were measured in a sample of 82 individuals. Cystatin C in sera was also measured as were GMT, alpha-1 microglobulin, albumin, total protein in urine. In all probands urinary clusterin was assayed (ELISA). RESULTS Urinary clusterin values correlated with urinary total protein concentrations (r = 0.28; p = 0.018), total protein/creatinine index (r = 0.26; p = 0.02). No correlation was found between urine clusterin concentration and glomerular filtration rate, age, urine GMT/creatinine, alpha-1-microglobulin, urine albumin and albumin/creatinine ratio or Na, K fractional excretions. We found no urinary clusterin differences by sex of probands. No evidence of any relationship between urine clusterin and presence of defect of renal function, number of risk factors (chi(2) = 16.0; DF = 15; p = 0.38), albumin/creatinine index (chi(2) = 0.76; DF = 3; p = 0,86), total protein/creatinine (chi(2) = 6.5; DF = 3; p = 0.09), GMT/creatinine (chi(2) = 2.3; DF = 3; p = 0.51), high urinary alpha-1-microglobulin (chi(2) = 4.1; DF = 3; p = 0.25) or decreased of GFR (chi(2) = 1.3; DF = 3; p = 0.74). CONCLUSIONS A positive correlation exists between urinary clusterin and urinary total protein and total protein/ creatinine index. Urinary clusterin measurement with ELISA test does not offer any advantage over routinely used parameters for nephropathy diagnosis and the differential diagnosis of proteinuria type.