Effect of estrogen replacement on insulin sensitivity, serum lipid and bone resorption marker in hypogonadal males

Recent reports of osteoporosis in congenital estrogen deficiency in humans from estrogen resistance or aromatase deficiency have called attention to the importance of estrogen in males. It is the purpose of the present study to evaluate the effects of low- dose estrogen on glucose, lipid and bone metabolism in males with hypogonadism. Nine Thai males with primary or secondary hypogonadism were included in the study. Testosterone was discontinued at least 8 weeks before the study. The subjects received 0.3 mg of conjugated equine estrogen (CEE) daily for 4 weeks. Serum C-terminal telopeptide of type 1 collagen (CTX), total cholesterol (TC), LDL cholesterol (LDL-C), HDL cholesterol (HDL-C), triglyceride (TG) and parameters related to insulin sensitivity were measured at baseline and 4 weeks after treatment. Insulin sensitivity was assessed by frequent intravenous glucose tolerance test. The mean age of subjects was 35.77 years (22-70 years). Insulin sensitivity index (SI) did not change significantly after the administration of CEE (P=0.09). Likewise, no change in acute insulin response (AIR(glucose)) was detected. However, glucose effectiveness (SG) significantly decreased after CEE (P<0.05). No significant change in serum TC, LDL-C, HDL-C or TG was detected. In regard to bone turnover, serum CTX significantly decreased after CEE administration (P<0.05). We concluded that low-dose estrogen administration in hypogonadal males for 4 weeks causes a decrease in bone turnover and an increase in glucose effectiveness. No effect on serum lipid concentrations or insulin sensitivity and secretion was detected.