Hypobilirubinemia Might be a Possible Risk Factor of End-Stage Kidney Disease Independently of Estimated Glomerular Filtration Rate

BACKGROUND/AIMS: The relationship between serum total bilirubin (TB) and estimated glomerular filtration rate (eGFR) is controversial and there is no report on the association between TB and end-stage kidney disease (ESKD). METHODS: We examined the cross-sectional association between TB and eGFR and investigated whether TB can predict ESKD with multivariable logistic regression adjusted for age, sex, and baseline eGFR using hospital-based data. RESULTS: The geometric mean TB of patients with eGFR ≥ 90 mL/min/1.73 m2 (S1), 8960 mL/min/1.73 m2 (S2), 59-30 mL/min/1.73 m2 (S3), 29-15 mL/min/1.73 m2 (S4), and < 15 mL/min/1.73 m2 (S5 = ESKD) was 0.55 mg/dL, 0.59 mg/dL, 0.56 mg/dL, 0.47 mg/dL, and 0.36 mg/dL (all p<0.0001 except for S1 vs. S3 where p=0.3726), respectively excluding patients with hyperbilirubinemia (TB > 1.24 mg/dL). The odds ratio (95% confidence interval) of incident ESKD for each 0.1 mg/dL increase in TB and hypobilirubinemia defined as TB ≤ 0.34 mg/dL were 0.92 (0.80-1.07) (p=0.2804) and 3.51 (1.56-7.88) (p=0.0023), respectively in patients with baseline eGFR ≥ 15 mL/min/1.73 m2 and 0.59 (0.37-0.95) (p=0.0283) and 6.03 (1.63-22.30) (p=0.0071), respectively in patients with baseline eGFR 29-15 mL/min/1.73 m2. CONCLUSIONS: Hypobilirubinemia might be a possible risk factor of ESKD.