Serum bilirubin level and its impact on the progression of chronic kidney disease.

PURPOSE: To examine whether an elevated serum total bilirubin level affects the decline in renal function or new-onset chronic kidney disease (CKD) in patients with type 2 diabetes mellitus (DM2).

METHODS: This was a longitudinal observational study in patients who presented at the University of Health Sciences Hospital in Kayseri. Five hundred twenty-nine patients with DM2 who had conserved renal function were enrolled (estimated glomerular filtration rate > 60 ml/min/1.73 m2 ). Arising CKD stage 3 was the outcome measure. The patients were separated into three groups based on the total serum bilirubin levels. The first group (G1) ranged from 0.1 to 0.3, the second (G2) 0.4-0.5, and the third (G3) 0.6-0.9 mg/dl. The effect of total serum bilirubin levels on CKD 3 development was assessed using Cox proportional hazards regression.

RESULTS: The risk of the CKD stage 3 development was highest in G1 who has the lowest serum total bilirubin levels (G1 vs. G3; hazard ratio [HR], 2.02; 95% confidence interval [CI] 1.21-3.36; p = 0.007). In addition, G2 had a significant risk of CKD stage 3 development (G2 vs. G3; hazard ratio [HR], 1.58; 95% confidence interval [CI] 1.08-2.32; p = 0.018). In the adjusted analysis, compared to G2 and G3, G1 had the highest risk (G1 vs. G3; hazard ratio [HR], 2.20; 95% confidence interval [CI] 1.29-3.77; p = 0.004). Similarly, G2 had a higher risk compared to G3 (hazard ratio [HR], 1.57; 95% confidence interval [CI] 1.05-2.34; p = 0.028).

CONCLUSIONS: Serum bilirubin may predict the progression of CKD in patients with type 2 diabetes and preserved kidney function.