繰り返す脆弱性骨折を契機に発見されたクッシング症候群の一例

A ３８-year-old woman had suffered from an avulsion fracture of the left cuboid bone, a rib fracture, a fatigue fracture of the left second metatarsal bone and a pubic fracture within the last ４ years. She also realized that her face was getting rounded and became aware of edema on extremities. She had repeated fragile fractures before menopause and was referred to our department on suspicion of secondary osteoporosis. The patients showed physical signs of moon face, central obesity, and abdominal violaceous striae. Cushing’s syndrome was suspected, therefore confirmatory studies were performed. Circadian variation of cortisol : serum cortisol１９．３μg／dL（at７：００）, ２１．４μg／dL（at２３：００）, urinary free cortisol :２４７．４μg／２４h, ACTH :２．５pg／mL. Low-dose（１mg） dexamethasone did not suppress cortisol level（１８．９μg/dL）. Based on these findings, we diagnosed as Cushing’s syndrome and glucocorticoid excess seemed to be the cause of secondary osteoporosis. Abdominal CT identified a ２．７ cm tumor in the left adrenal gland, and in-phase T１‐weighted MRI showed decreased signal compared to out-phase, suggesting an adrenocortical adenoma. She underwent laparoscopic left adrenalectomy. Postoperative fasting serum cortisol decreased to２．２ μg/dL, and glucocorticoid replacement therapy was started. It is necessary to find out any secondary causes for premenopausal women with fragility fractures. It is well known that endocrine disorders including Cushing’s syndrome are the most frequent associated diseases in patients with premenopausal osteoporosis. Cushing’s syndrome should be considered as a causative disease in premenopausal women with osteoporosis.