Cushing's syndrome and bone.

Structural and functional impairment of skeletal system is a relevant cause of morbidity and disability in patients with Cushing's syndrome (CS). Approximately 30-50% of patients with CS experience fractures (particularly at the spinal level) consistent with the 50% incidence of osteoporosis. Growth failure, pubertal arrest are the hallmarks of CS in children and growing adolescents leading to reduced final adult height and peak bone mass. The decrease in osteoblast number and function, through different mechanisms, seems to play a central role in the bone loss in CS. Patients with CS have decreased serum levels of osteocalcin and alkaline phosphatase. Considering the preferential bone loss in the cancellous skeleton it is reasonable to measure BMD, possibly with Dual X-rays absorptiometry (DEXA) at lumbar spine, in all patients with CS. Patients cured from CS have increased prevalence of spine damage: therefore, a radiological follow-up of the skeleton should be included in the management of patients with CS not only during the active phase but also after cure. Glucocorticoid-induced osteoporosis is reversible. The recovery of bone loss in CS is slow, taking approximately ten years to become complete. In the meanwhile, patients with severe osteopenia are exposed to a high risk of fracture. Alendronate may induce a more rapid improvement in BMD than cortisol normalization alone and it could be useful in patients with persistent postsurgical hypercortisolism to prevent further bone loss. The decision to discontinue antiresorptive therapy should be based on clinical monitoring and DEXA measurements.