The liver-kidney axis: Is serum leptin a potential link in non-alcoholic fatty liver disease-associated chronic kidney disease?

Background And Study Aims: Non-alcoholic fatty liver disease (NAFLD) is an independent risk factor for chronic kidney disease (CKD). Previous studies argued that leptin levels increase significantly with the progression of CKD. But the association between leptin and CKD has not been investigated in patients with NAFLD. Therefore, we conducted this study to establish whether increased leptin level is associated with CKD in NAFLD patients.

Patients And Methods: In our prospective study with a follow up period of six months thirty-five teetotaller biopsy-proven NAFLD patients were divided as groups with mild, versus advanced, fibrosis. Liver fibrosis was also assessed with Fibroscan. Serum leptin levels were measured by radioimmunoassay. For insulin resistance we used the homeostasis model assessment method (HOMA-IR). For the kidney function, we used the abbreviated formula Modification of Diet in Renal Disease (MDRD) formula, which estimates GFR. For statistical analysis, Student's-t test, Mann-Whitney test, linear regression-binary logistic regression analyses and the ROC curve analysis were used.

Results: Advanced fibrosis and increased HOMA-IR were risk factors for decreased eGFR. Leptin correlated inversely with advanced fibrosis (p: 0.03) and low leptin was a risk factor for CKD (p: 0.02). In ROC curve analysis, advanced fibrosis and low leptin were risk factors for decreased eGFR (p: 0.007 and 0.004, respectively). Low leptin level was dependently associated with decreased eGFR.

Conclusion: Advanced fibrosis in NAFLD patients is a risk factor for CKD. Leptin correlated inversely with advanced fibrosis. Unlike the previous studies, which were not performed in NAFLD patients, we found decreased leptin in NAFLD patients with decreased eGFR. Low leptin level was found to be a dependent predictor for differentiating NAFLD patients with high risk for CKD.