Relationship between kidney function and liver histology in subjects with nonalcoholic steatohepatitis.

BACKGROUND AND OBJECTIVES We assessed whether nonalcoholic steatohepatitis (NASH) diagnosed by liver biopsy is associated with decreased kidney function and whether such association is independent of insulin resistance and features of the metabolic syndrome. DESIGN, SETTINGS, PARTICIPANTS, & MEASUREMENTS We enrolled 80 consecutive overweight patients with biopsy-proven NASH and 80 nonsteatotic control subjects who were matched for age, gender, and body mass index. Chronic kidney disease (CKD) was defined as the presence of estimated GFR (eGFR) of ≤60 ml/min per 1.73 m(2) and/or abnormal albuminuria (i.e., urinary albumin/creatinine ratio ≥30 mg/g). RESULTS NASH patients had significantly (P < 0.001) lower eGFR (75.3 ± 12 versus 87.5 ± 6 ml/min per 1.73 m(2)) and a greater frequency of abnormal albuminuria (14 versus 2.5%) and CKD (25 versus 3.7%) than control subjects. The significant differences in eGFR, albuminuria, and CKD that were observed between the two groups were only slightly weakened after adjustment for age, gender, body mass index, smoking status, insulin resistance (by homeostasis model assessment), and components of the metabolic syndrome. Notably, histologic severity of NASH (i.e., fibrosis stage) was strongly associated with either decreasing eGFR or increasing albuminuria (P < 0.01 or less), independently of potential confounding factors. CONCLUSIONS Our findings suggest that patients with biopsy-proven NASH have moderately decreased eGFR and a higher frequency of abnormal albuminuria and CKD than matched control subjects and that the severity of NASH histology is associated with decreased kidney function, independently of traditional risk factors, insulin resistance, and components of the metabolic syndrome.