Urine and serum fetuin-A levels in patients with urolithiasis

INTRODUCTION: Fetuin-A is a glycoprotein secreted by liver and has been shown to inhibit extraosseous mineralization. Urolithiasis may be a manifestation in the urinary tract due to fetuin deficiency in urine. The objective of this study was to compare the 24-h urine and serum fetuin-A levels of patients with and without urolithiasis. METHODS: Serum and 24-h urine fetuin-A levels were measured in 41 patients with bilateral, multiple, or recurrent urinary tract calculi (Group A) and 41 matched controls with no calculi (Group B). Fetuin levels were measured by enzyme linked immunosorbent assay. Serum and urine fetuin-A levels in the two groups were compared. RESULTS: The median (range) 24-h urine fetuin-A value in Group A was 11.9 (1.12–221) mg/day and in Group B was 37.7 (1.28–125) mg/day. This difference was statistically significant (Mann–Whitney test, P = 0.0169). The median (range) serum fetuin-A in Group A was 0.67 (0.05–2.68) g/L and in Group B was 0.99 (0.01–5.5) g/L. The difference between serum values in the two arms was not statistically significant (Mann–Whitney test, P = 0.1817). However, the serum creatinine-adjusted mean log serum fetuin and urine fetuin were significantly different in the two arms (P = 0.003). The mean ± standard deviation (range) serum creatinine in Group A was 0.98 ± 0.25 (0.56–1.58) mg% and in Group B was 0.83 ± 0.16 (0.58–1.18) mg% (two sample t-test, P = 0.0031). CONCLUSIONS: Patients with urolithiasis have lower urine fetuin-A and creatinine-adjusted serum fetuin-A levels.