Introduction: The most important feature of bone metabolism in patients with Cushings syndrome is the uncoupling of osteoblast and osteoclast activity resulting in suppressed bone formation.
Objective: The aim of the present study was to investigate the altered bone turnover in patients with various forms of Cushings syndrome in the active phase of the disease as well as after successful normalization of cortisol overproduction.
Patients and methods: This retrospective study included 63 patients with Cushings syndrome (38 Cushings disease, 6 ectopic ACTH syndrome, 19 ACTH-independent adrenal disease).The patients were monitored over a period of up to 48 months after treatment or up to the recurrence of their disease. Patients with known metabolic bone disease, or with medication affecting bone mineral content were excluded. 148 blood samples were evaluated (67 samples from active and 81 samples from inactive phase of Cushings syndrome).Serum osteocalcin (OC) and type I collagen breakdown products (beta-CrossLaps, β-CL) were measured with standard test kits. SPSS v13.0 software package was used for statistical analysis.
Results: OC concentration which was suppressed in the active phase of the disease (mean, 12.1±8.0 ng/ml) increased to 38.0±26.0 ng/ml within the first month after the effective therapy, reached the maxiumum level after 6 months (52.3±33.6 ng/ml) and became normal after the second year. There were no significant changes in β-CL concentrations. Using ROC analysis, 17.2 ng/ml serum OC concentration was found as the best cutoff value in differentiating between active and inactive phase of bone disease related to Cushings syndrome. The sensitivity and specificity of OC at this concentration were 87.1% and 82.1%, respectively.
Conclusion: Our results indicate that the suppressed serum OC concentration increases rapidly and elevates above the normal range after treatment of Cushings syndrome. Markers of bone turnover are normal after the second year of the cure of Cushings syndrome.
28 Apr - 02 May 2007
European Society of Endocrinology