Relationship of nonalcoholic hepatic steatosis to overnight low-dose dexamethasone suppression test in obese individuals

OBJECTIVES To examine the association between nonalcoholic hepatic steatosis (HS) and the activity of the hypothalamo-pituitary-adrenal (HPA) axis, as evaluated by a low-dose dexamethasone suppression test, in obese subjects. DESIGN AND PATIENTS In a cross-sectional study, we examined 54 obese, otherwise healthy, individuals with a negligible or zero daily alcohol consumption. MEASUREMENTS HS (by ultrasonography), glucose tolerance status (by oral glucose load), insulin resistance [by homeostasis model assessment (HOMA)] and 1.0 mg postdexamethasone (postdex) suppression cortisol levels were measured. RESULTS Subjects with nonalcoholic HS (n = 39) had markedly less suppressed circulating cortisol levels than those without HS (n = 15) (21.9 +/- 2.6 vs. 11.0 +/- 1.4 nmol/l, P < 0.001). In addition, subjects with nonalcoholic HS had significantly higher values of HOMA-insulin resistance score and circulating liver enzymes than their counterparts without HS. Age, body mass index (BMI), waist/hip ratio, plasma glucose concentration (both at fasting and after glucose load), lipids and blood pressure values did not differ significantly between the groups. Females were more represented among those without HS. The marked differences in postdex suppression cortisol levels that were observed between the groups were little affected by adjustment for sex, age, BMI, waist/hip ratio, HOMA-insulin resistance score, plasma lipids and liver enzyme levels. Similarly, in a logistic regression analysis, cortisol levels significantly predicted the presence of nonalcoholic HS (P = 0.032), independently of potential confounders. CONCLUSIONS These results suggest that nonalcoholic hepatic steatosis is closely correlated with a subtle, chronic activation of the HPA axis in obese, otherwise healthy, individuals.