Weight-loss independent effects of bariatric surgery on ALT levels

Shira Azulai ¹ Ronit Grinbaum ² Nahum Beglaibter ² Shai Meron Eldar ³ Moshe Rubin ⁴ Orit Blumenfeld ⁵ Orly Romano-Zelekha ⁵ Rachel Ben-Haroush Schyr ¹ Danny Ben-Zvi ¹
¹Department of Developmental Biology and Cancer Research, the Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Israel
²Department of Surgery, Hadassah-Hebrew University Medical Center, Mount Scopus, Israel
³Bariatric Surgery Unit, Department of General Surgery, Tel-Aviv Sourasky Medical Center, Affiliated with the Sackler School of Medicine, Tel Aviv University, Israel
⁴Department of Surgery, The Sheba Medical Center, Tel Hashomer, Israel
⁵Israel Center for Disease Control, Ministry of Health, Israel

Patients that underwent bariatric surgery also display improvement in HbA1c levels and a decrease in plasma liver enzymes ALT and AST- yet indications for surgery remain almost entirely BMI dependent. Here we show that some of the metabolic benefits of the surgery can be obtained regardless of the decrease in BMI levels. Using 2-year follow-up data from the Israeli Bariatric Registry we found that the change in ALT does not correlate with the initial levels or change in BMI and HbA1c. We provide evidence for a significant decrease in ALT enzymes that is weight-loss independent: First, patients who regained all lost weight display a reduction in ALT levels. Second, ALT levels are reduced 2 years after surgery in a retrospective cohort of patients matching for BMI, HbA1c, age, sex, ethnicity and smoking before and after surgery. These results reinforce the hypothesis that bariatric surgery itself changes metabolic pathways that can improve non-alcoholic liver disease, the hepatic manifestation of the metabolic syndrome independent of weight-loss in patients.