Decreased bone mineral density (BMD) and disturbances in glucose metabolism are common complications of Cushings disease. Many recent studies have shown that hyperinsulinemia in type 2 diabetes mellitus (DM) may lead to higher BMD as compared to healthy individuals. The aim of the present study was to investigate the possible relationships between BMD, serum markers of bone metabolism and plasma cortisol concentrations. The second objective was to determine whether the presence of impaired glucose metabolism could have an impact on BMD in Cushings disease.
The study included 66 patients with Cushings disease (14 males, 52 females; mean age 33.4±12.5 years). BMD measurements were performed by DEXA at the lumbar spine (LS), left femoral neck (FN) as well as at the total proximal femur (TF). Of the 32 patients without unequivocal DM, oral glucose tolerance test (oGTT) showed normal oGTT in 18 patients (32%) (subgroup 1, SG1), impaired glucose tolerance in 14 patients (24%) and DM in 25 patients (44%). The latter two subgroups were considered as subgroup 2 (SG2).
In the whole group of patients, mean BMD z-scores (±S.D.) were decreased at all regions (LS, −1.60±1.04; FN, −1.12±1.06; TF, −0.99±1.01). There were no correlations between BMD z-scores at any site and plasma cortisol concentrations at 08 h, 24 h, or after a low-dose dexamethasone test (LDDT). In contrast, significant negative correlations were found between osteocalcin levels and cortisol concentrations at 08 h (P<0.001), at 24 h (P<0.05) and after LDDT (P<0.001). Patients in SG2 had significantly higher BMD z-scores at TF (P<0.01) and lower osteocalcin concentrations (P<0.001) compared with patients in SG1.
Our results suggest that the severity of bone disease in patients with Cushings disease fails to correlate directly with plasma cortisol concentrations. It is possible that the presence of insulin resistance often present in patients with Cushings disease may have an anabolic effect on bones.
01 - 05 Apr 2006
European Society of Endocrinology