Effectiveness of chronic treatment with alendronate in the osteoporosis of Cushing's disease

BACKGROUND Osteoporosis is common in patients with Cushing's disease and is likely due to an imbalance between bone formation and resorption. Alendronate is an aminobisphosphonate that is able to increase bone mass mainly by inhibiting bone resorption. OBJECTIVE We have evaluated the effect of chronic treatment with alendronate on bone mineral density (BMD) in patients with Cushing's disease. PATIENTS 39 patients with Cushing's disease entered this study. 39 age-, sex- and BMI-matched normals served as controls for baseline evaluation. The 39 patients were divided into four groups: 1) 10 patients with active disease treated with alendronate and ketoconazole; 2) 11 patients with inactive disease treated with alendronate; 3) 8 patients with active disease treated with ketoconazole alone, 4) 10 patients with inactive disease received no treatment. TREATMENT PROTOCOL Alendronate was given for 12 months in a dose of 10 mg orally once daily after fasting at 0800h in the morning. Ketoconazole was given in a dose of 200-600mg orally daily, when pituitary surgery was unsuccessful. STUDY DESIGN Lumbar spine (L1-L4) and femoral neck BMD, serum osteocalcin (OG), urinary crosslinked N-telopeptides of type I collagen (Ntx) levels were evaluated at study entry, in patients and controls, and were repeated after 6 and 12 months in the 39 patients. RESULTS BMD values were lower in patients with Cushing's disease than in controls at both L1-L4 (0.72 +/- 0.4 vs. 1.01 +/- 0.6 g/cm(2), P<0.05) and femoral neck (0.69 +/- 0.3 vs. 0.96 +/- 0.6 g/cm(2), P<0.05). In the 39 patients with Cushing's disease considered as a whole, serum OG levels were lower (1.1 +/- 0.1 vs 1.5 +/- 0.1 nmol/l, P<0.01), while Ntx values were higher than in controls (168 +/- 25 vs. 61 +/- 31 nmol BGE/mmol creatinine, P<0.01). In the alendronate-treated groups, serum OG levels increased, while Ntx levels significantly decreased after 6 and 12 months of treatment without any significant difference between the two groups. BMD values measured at L1-L4 and femoral neck significantly increased after 12 months of therapy. In patients of group 4, a significant increase of serum OG levels and a significant decrease of Ntx levels were observed together with a slight increase of BMD values after 12 months. No significant change in either biochemical markers or BMD values was found in patients of group 3. CONCLUSIONS Patients with Cushing's disease have osteoporosis which needs to be rapidly reversed to limit the risk of fracture. The results of the present study show that a 12 month treatment period with alendronate induced an improvement in bone mineral density greater than in untreated patients.