Liver Enzymes (ALT, GGT), Insulin Resistance and Hepatic Steatosis at Ultrasonography in Obese And Severely Obese Patients

Background and aim: In obesity, a cluster of metabolic alterations is often associated with Fatty Liver (FL). The bright liver at abdominal ultrasonography (US) and, in most cases, increased levels of hepatic enzymes, alanine aminotransferase (ALT) and gamma-glutamyltranspeptidase (GGT), are considered the hallmarks of Nonalcoholic Fatty Liver Disease (NAFLD). Moreover in obesity, insulin resistance (IR) is reported to be closely related to FL. Metabolic and liver enzymes alterations were investigated in a population of obese and severely obese patients (BMI>40); patients with FL or without FL at US were compared. Material and methods: From March 2003 through October 2007, 146 patients (F 102; age 20-63 yrs) with obesity and severe obesity (BMI 32-62) were consecutively admitted to our digestive endoscopy service (Malatesta Novello Hospital, Cesena, Italy) for the intragastric balloon insertion. US, clinical and routine laboratory investigations were determined. IR was calculated by the Homeostasis Model Assessment (HOMA-IR), as fasting serum insulin (mU/ml) x fasting plasma glucose (mmol/l)/22.5; values >2.5 indicate a state of IR. Patients with HBV(+), HCV(+), alcohol consumption >20g/day, and steatogenic drugs in the history, were excluded. Statistical analysis was performed using SPSS 15.0 software. Results: In all patients BMI median value was 40 kg/m2. US showed FL in 60% pts. FL (88) group was compared with noFL (58) group, the values of HOMA-IR (4.8±3.1 vs 3.8±2.2, p<.05), ALT (41.8±43.9 vs 23.3±14.2, p<.01), GGT (35.3±27.2 vs 20.5±13.6 p<.001), Triglycerides (202.8±145.3 vs 135.6±60.9, p<.01) were significantly different. Glucose and HDL-cholesterol did not differ. HOMA-IR correlated significantly with ALT, in noFL and FL (R2=0.12 and R2=0.05; p<.05) or with GGT, only in noFL (R2=0.175; p<.001). Conclusions: In all obese patients with FL at US, liver enzymes (ALT, GGT) and HOMA-IR values were higher than in noFL, confirming the pivotal role of IR in liver damage due to visceral adiposity. As previously reported by Marchesini et al (2005), we confirm ALT could be considered a marker of hepatic dysfunction in obesity, more sensitive than GGT.