Effect of Roux-en-Y Gastric Bypass (RYGB) on Clinical and Laboratory Data in Morbidly Obese Patients

Abstract

Purpose: Roux-en-Y Gastric Bypass (RYGB) is the most common and effective procedure performed in the US for surgical treatment of obesity. The likelihood of having non-alcoholic fatty liver disease (NAFLD) is directly proportional to body weight1. NAFLD is being increasingly recognized as a major cause of liver-related morbidity and mortality. Given the increasing prevalence of obesity in North America, NAFLD is an important public health problem. The aim of this study is to determine the incidence of NAFLD in patients who underwent RYGB and to determine the effect of RYGB in a subgroup with abnormal liver tests (which include AST, ALT, alkaline phosphatase and bilirubin). Methods: 400 consecutive patients who underwent RYBP were evaluated retrospectively. Only those who underwent random intra-operative liver biopsy were included. Patients with viral or autoimmune hepatitis, hemochromatosis or alcohol use (>20g/day) were excluded. Pathological analysis recorded the presence and degree of steatosis, portal and lobular inflammation, and ballooning. Preoperative and 6–8 month postoperative clinical and laboratory data was gathered which included age, BMI, AST, ALT, alkaline phosphatase (AP) and bilirubin. Paired t-test was used to compare these variables pre and post operatively. Results: 205 patients were included in the study. 86.3% were female. The mean age was 36.8 ± 10.1 years. The mean BMI was 48.7 ± 7.4 kg/m2. 90.7% had NAFLD as proven by liver biopsy. All the patients with normal liver biopsy had normal liver tests. 25.9% of patients with NAFLD had abnormal liver tests prior to RYGB. Of these patients with abnormal liver tests, 24.5% had abnormal AST, 38.9% had abnormal ALT, 71.7% had abnormal AP and 9.4% had abnormal bilirubin. There was significant improvement of ALT (p= <0.001), AP (p= <0.001) and bilirubin (p= 0.003) after adjusting for the decrease in BMI postoperatively. Conclusions: Our study reiterates that NAFLD is highly prevalent in morbidly obese patients. About one-fourth of morbidly obese patients have abnormal liver tests. Significant improvement of ALT, alkaline phosphatase and bilirubin was noted after bariatric surgery.