Impaired renal function in morbid obese patients with nonalcoholic fatty liver disease

Obesity is a common risk factor for nonalcoholic fatty liver disease (NAFLD) and chronic kidney disease (CKD). NAFLD and CKD have been associated in many epidemiological studies. We hypothesize that more severe liver disease, namely nonalcoholic steatohepatitis (NASH), is related with further renal impairment. We aimed to evaluate if changes in renal function were present in morbid obese patients with NAFLD.

Prospective and consecutive recruitment of morbid obese patients with biopsy proven NAFLD obtained during bariatric surgery. Renal function was evaluated with CKD-Epidemiology Collaboration estimated glomerular filtration rate (eGFR). Plasmatic adiponectin, leptin and active ghrelin concentrations were determined.

One hundred and forty-eight patients were included of whom 25% had NASH and 75% simple steatosis. NASH patients were older, with higher body mass index and had more frequently metabolic syndrome and lower eGFR (97 ± 22 vs 106 ± 16 ml/min/1.73(2), P = 0.035). NASH conferred an odds ratio (OR) 3.0 (1.3-7.0) for eGFR < 90 and OR 9.7 (1.0-96.4) for eGFR < 60 ml/min/1.73(2). eGFR < 90 ml/min/1.73(2) associated with aspartate aminotransferase [OR 2.9 (1.1-7.6)] and γ-glutamyl transpeptidase elevation [OR 3.0 (1.3-7.2)], NASH [OR 3.0 (1.3-7.0)], any lobular inflammatory activity [OR 3.0 (1.3-7.0)] and severe fibrosis [OR 3.4 (1.1-10.8)]. Neither eGFR nor liver histology was associated with adipokines levels.

In morbid obese patients, NASH, particularly lobular inflammation and advanced fibrosis, associates with mild decreases in eGFR, suggesting a common inflammatory link between liver and renal lesion.