Long-term follow-up of bone mineral density in Addison's disease

There is conflicting evidence regarding the long-term effects of long-term glucocorticoid replacement therapy (GRT) on bone mineral density (BMD) in patients with chronic adrenal insufficiency. Our aim was to evaluate bone turnover and changes in BMD in patients on GRT.

We have studied 25 subjects (six men, 19 women; aged 62.4 +/- 11.3 years, duration of disease 21.7 +/- 11.7 years, fasting cortisol 63 +/- 36 nmol/l) on GRT (hydrocortisone 30 mg/day or prednisone 7.5 mg/day). BMD was assessed at the lumbar spine (LS; L2-L4), proximal femur (PF) and ultra distal radius (UR) by dual energy X-ray absorptiometry (DXA). The rates of bone loss were calculated using previous DXA measurements at the LS (48 and 60 months earlier). Serum calcium, phosphate alkaline phosphatase (ALP), bone ALP, serum osteocalcin (BGP), intact parathyroid hormone (PTH) and 25(OH) vitamin D were also measured.

BMD [Z-score; 95% confidence interval (95% CI)] was normal at the LS: (-1.15-+0.07); PF: (-0.90-+0.22) and UDR (-0.77-+0.36). No significant differences were found according to the type of replacement therapy or sex. No significant bone loss (g/cm2; 95% CI) was detected at the LS: (-0.021-+0.023). Fifty-six per cent of patients met osteoporotic criteria; a greater proportion of patients treated with prednisone had osteoporosis compared with those an hydrocortisone. All bone markers were in their normal ranges.

Patients on long-term therapy do not show accelerated bone loss at the lumbar spine. Nevertheless, a considerable proportion of patients, mainly those treated with prednisone, showed densitometric osteoporosis.