Objective: Cushing's syndrome (CS) is a well recognized cause of bone loss. Although many previous studies have shown decreased bone mineral density (BMD) in the lumbar spina and proximal femur of patients with endogenous CS, so far, the data estimating BMD in their peripheral skeleton are sparse. The aim of the present study was to evaluate BMD in the forearm and heel of women with newly diagnosed CS and to investigate its possible correlation with serum osteocalcin (BGP) and 24-hour urinary free cortisol levels (UFC).
Patients and methods: BMD in the forearm (distal and ultradistal area) of 29 (13 premenopausal and 16 postmenopausal) women with newly diagnosed CS (18 with pituitary adenoma, 10 with adrenal tumor and 1 with ectopic) was measured by dual x-ray absorptiometry (DEXA) and was compared with BMD of 29 age, body mass index (BMI)- and oestrogen status matched healthy controls. Furthermore, in 18 (9 premenopausal and 9 postmenopausal) of the above patients (14 with pituitary adenoma, 5 with adrenal tumor and 1 with ectopic) broadband ultrasound attenuation (BUA) by quantitative ultrasound (QUS) of the heel was estimated and 18 age-, BMI- and oestrogen status matched healthy women served as controls. In all the patients serum BGP and UFC were measured at the time of diagnosis of CS.
Results: Compared to their matched controls, BMD in the forearm and BUA values in the heel did not differ in the premenopausal women with CS, while in the postmenopausal group BMD in the forearm was decreased (P < 0.05) but not BUA. Apart from a weak negative correlation between serum BGP and BMD in the ultradistal site of the forearm in premenopausal women (P = 0.05), serum BGP and UFC did not show significant correlation with BMD or BUA.
Conclusions: BMD in the forearm is reduced only in postmenopausal women with newly diagnosed endogenous CS, while BUA in the heel is unaffected in both pre- and postmenopausal patients. Moreover, serum BGP and UFC do not seem to be relevant markers for assessing bone loss in the peripheral skeleton at the time of diagnosis of hypercortisolemia.