Renal resistive index in non-alcoholic fatty liver disease as an indicator of early renal affection

Background Nonalcoholic fatty liver disease (NAFLD) is a possible risk factor for chronic kidney disease (CKD). Renal resistive index (RRI) which is a ratio of peak systolic and end diastolic velocity can test arterial stiffness and endothelial renal dysfunction. The aim of the work is to detect the relation between NAFLD and RRI as an indicator of early renal affection and its relation to the disease severity. This study included 150 subjects divided into 3 groups: patients with NASH, simple steatosis, and control group (50 patients each). All patients were subjected to full history taking, clinical examination, laboratory investigations, abdominal ultrasound examination, and RRI measurement. Results 6.0% of NASH patients had significant fibrosis by NAFLD fibrosis score. RRI was significantly higher in NASH patients with fibrosis (mean = 0.74) than NASH patients without fibrosis (mean = 0.65) and patients with simple steatosis (mean = 0.63). It was the lowest in normal controls (mean = 0.61). There were significant correlations between RRI and age, BMI, serum lipids, liver enzymes, and NAFLD fibrosis score. Multiple linear regression analysis found that age and serum cholesterol were significant independent factors of increased RRI ( p < 0.0001). RRI showed low diagnostic performance in differentiation between NASH and simple steatosis using ROC curve. Conclusion RRI was significantly higher in NASH patients with and without hepatic fibrosis. RRI correlates significantly with NAFLD fibrosis score. RRI can be used as an indicator of early renal affection in patients with NAFLD.