Alteration in skeletal muscle mass in women with subclinical hypercortisolism

Despite the well-known deleterious effects of cortisol on skeletal muscle, whether subtle cortisol excess in subclinical hypercortisolism (SH) affects skeletal muscle mass is unknown. Our objective was to understand the effects of the cortisol level on skeletal muscle mass in patients with SH. We compared skeletal muscle mass and fat mass (FM) between 21 patients with SH (12 women and 9 men) and 224 controls (67 women and 157 men) with nonfunctioning adrenal incidentaloma (NFAI). Medical records were reviewed, and we measured body composition parameters using bioelectrical impedance analysis and serum cortisol levels after the overnight 1-mg dexamethasone suppression test (DST). After adjusting for confounding factors, 1-mg DST levels were inversely correlated with appendicular skeletal muscle mass (ASM) (gamma = -0.245, P = 0.040), lower limb ASM (gamma = -0.244, P = 0.040), and appendicular skeletal muscle index (ASMI; height-adjusted ASM) (gamma = -0.229, P = 0.048) in all women, but not men. ASM and ASMI were significantly lower by 6.2% (P = 0.033) and 5.9% (P = 0.046), respectively, in women with SH compared with those with NFAI, but not men. Conversely, FM and percent fat mass were similar between the two groups. Compared with women with NFAI, among those with SH, lower limb, but not upper limb, ASM was lower by 6.8% (P = 0.020). This study showed that women with SH had lower skeletal muscle mass, especially of the lower limb, and suggested that subtle cortisol excess also has adverse effects on skeletal muscle metabolism.