Obesity, a major risk factor for fatty liver disease, is increasing worldwide. Morbid obese patients have a higher prevalence of fatty liver disease in addition to more severe complications, and high prevalence of abnormal liver function tests (LFTs). The aim of this study is to determine the pattern of LFT and liver ultrasonography of morbid obese Iranian patients undergoing bariatric surgery.

The study population included 308 morbid obese patients who were candidates for Laparoscopic Roux-en-Y Gastric Bypass surgery. Body mass index (BMI), age, gender, weight, height, blood tests including alanine transaminase (ALT), aspartate transaminase (AST), direct bilirubin (Bil D), total bilirubin (Bil T), and liver ultrasound reports were recorded for all of the patients. Patients with alcohol intake or hepatitis or human immunodeficiency virus (HIV) were excluded from the study. The data were entered and analyzed using SPSS-16. The chi-square, ANOVA and Independent-sample t- test used in the study analysis.

Data analyses showed that alkaline phosphatase (ALKP) is the most elevated serum enzyme in morbid obese patients 26 (87.6%). ALT, AST, bilirubin total and bilirubin direct were more than upper normal range in 70 (24.1%), 80 (26%), 2 (1.5%) and 15 (11.4%) in all patients, respectively. Ultrasonography of the liver showed that fatty liver disease occurred in approximately 280 (91%) of our patients. In our study, the only liver enzyme that had significant difference with fatty liver and normal groups was AST (P: 0.027). The patients were divided into three groups on the basis of the BMI: BMI of 35 - 40 kg/m², 40 - 50 kg/m², and above 50 kg/m². There is not any significant difference between the mean of ALKP, ALT, AST, bilirubin (direct and total) serum level and fatty liver in these three groups.

The prevalence of abnormal LFTs in Iranian morbid obese patients is in high status especially the level of ALKP. Liver ultrasonography has high sensitivity for the fatty liver in morbid obese patients but LFTs rise only in few patients with fatty liver.