Effects of obstructive sleep apnea syndrome on serum aminotransferase levels and insulin resistance

Bckground: Patients with obstructive sleep apnea (OSA) are at risk of developing the fatty liver as a result of being overweight. Several studies suggest that OSA per se could be a risk factor for liver injury; and ischemic hepatitis with OSA. The OSA is an independent risk factor for Insulin resistance. Therefore, we investigated liver enzymes and insulin resistance in patients with OSA, and compared with controls. Methods: Eighty-one consecutive patients with clinical suspicion of OSA were referred to the Sleep Unit of Masih Daneshvary hospital. On the basis of Polysomnography results patients were divided into two groups: The OSA and non-OSA cases, and also patients without OSA were used as internal controls. The Serum levels of liver enzymes were measured in all patients and abdominal ultrasound examination performed for screening the fatty liver and its grading. Insulin resistance was calculated via homeostasis model assessment (HOMA). Results: The OSA was present in 41 and absent in 40 patients. Age, sex and body mass indices were not significantly different in two groups. The mean of alanine aminotransferase (ALT) was 31.24±14.05 IU/L in OSA and 29.97±8.9 IU/L in non-OSA (p= 0.349) and aspartate aminotransferase (AST) was 29.07±9.6 IU/L in OSA and 26.85±6.7 IU/L in non-OSA (p= 0.389). The mean of HOMA was 2.05±18.2 in OSA and 1.5±0.54 in non-OSA (p< 0.001). Conclusion: This study shows that OSA, independent of overweight conditions, is not a risk factor for abnormal liver enzymes. However, the OSA per se seems to be associated with increase in insulin resistance and severity of fatty liver.