Severe impairment of bone mass and turnover in Cushing's disease: Comparison between childhood-onset and adulthood-onset disease

BACKGROUND: Osteoporosis is an important, frequently unrecognized consequence of hypercortisolism. OBJECTIVE: To evaluate whether the age of onset of hypercortisolism influences its effects on bone mass and turnover. SUBJECTS: 10 with childhood-onset (co) and 18 with adulthood-onset (ao) Cushing's disease (CD); 28 age-, sex- and body mass index (BMI)-matched healthy subjects served as controls. STUDY DESIGN: Open, cross-sectional controlled. MEASUREMENTS: Bone mineral density (BMD) at lumbar spine, serum osteocalcin (OC), and urinary N-telopeptides of type I collagen (Ntx) levels. RESULTS: BMD at lumbar spine was significantly lower in all CD patients than in controls (Z score, -2.3 ± 0.1 vs. -0.2 ± 0.01; P < 0.001). co-CD and ao-CD patients had similar values of bone mass when expressed as Z score (-2.6 ± 0.4 vs. -2.1 ± 0.2; P = 0.27) or as BMD (0.728 ± 0.03 vs. 0.78 ± 0.03 g/cm ²; P = 0.25). In particular, osteoporosis was observed in 16 patients (57.1%) [eight adolescents (80%) and eight adults (44.4%)] and none of the controls; osteopenia was found in two co-CD patients (20%) and none of the healthy adolescents, 10 ao-CD patients (55.6%) and four healthy adults (14.3%) (χ ² = 7.87, P < 0.01; χ ² = 2.99, P = 0.09, respectively). In co-CD and ao-CD patients, serum OC levels were similar and significantly lower than in controls (P < 0.01); urinary Ntx levels were significantly higher than in controls (P < 0.001) and were significantly higher in co-CD than in ao-CD patients (P < 0.001). No significant correlation was found between urinary cortisol levels, serum cortisol and age and lumbar Z score values, while a significant correlation was found between Ntx levels and disease duration (r = 0.434; P = 0.021) and plasma cortisol (r = 0.440; P = 0.019). CONCLUSIONS: Cushing's disease causes bone loss and abnormalities of bone turnover both in childhood-onset and in adulthood-onset patients. A strict follow-up of bone mass and turnover is mandatory in all patients with Cushing's disease to prevent fractures later in life and specific treatment for bone loss is strongly suggested.