Microalbuminuria as a possible marker of risk of Balkan endemic nephropathy

Aim: To evaluate whether microalbuminuria could be a marker of early tubular damage in individuals at risk of developing Balkan endemic nephropathy (BEN). Methods: A cross-sectional study was used to determine urinary albumin-to-creatinine ratio (UACR) in a test group of 61 participants from a BEN endemic region and control group of 64 participants from a nearby non-endemic region, both recruited from the general population of Bosnia and Herzegovina. The correlation between UACR and urinary b2 microglobulin-to-creatinine ratio (UBCR) and the receiver operating characteristic curve for UACR were analyzed in the test groups of 58 participants. The correlation analysis was also performed in a subset of nine subjects with elevated UBCR. Results: Medians, interquartile ranges and confidence intervals (CI) for medians of UACR in the test and control groups were 2 mg/mmol, 0.975–8.247 mg/mmol, 1.3472–3.2691 mg/mmol and 1 mg/mmol, 0.695–1.41 mg/mmol, 0.8466–1.2053 mg/mmol, respectively (P = 0.0001). Microalbuminuria was found in 30 of the 61 examinees in the test group, in contrast to six of the 64 examinees in the controls (P < 0.0001). Participants from the endemic region had 9.3 times the odds of having microalbuminuria in contrast to participants from the non-endemic region. Pearson's correlation coefficients r of the log-transformed ratios and Kendall–tau coefficients of rank correlation in the group of 58 and in a subset of nine subjects with elevated UBCR were: 0.55 (P < 0.0001); 0.317 (P = 0.0005) and 0.59 (P = 0.045); 0.48 (P = 0.037), respectively. The area under the curve for UACR was 0.882 (P = 0.0001), sensitivity 100% and specificity 67.3%. Conclusion: Microalbuminuria may be a useful marker of early tubular injury in individuals at risk of developing BEN.