Osteoporosis in mixed connective tissue disease

The existence of osteoporosis in 58 postmenopausal women with mixed connective tissue disease (MCTD) was investigated. The mean bone mineral density assessed by dual energy X-ray absorptiometry in the lumbar spine was decreased in 25.8% of the patients, reflecting osteoporosis (T score < -2.5). In the femoral neck there was no significant difference between the BMD of MCTD patients and that of age-matched, healthy postmenopausal women. Low bone mineral density was found among patients on, as well as off, corticosteroids. The extent of bone loss was associated with disease duration, as well as corticosteroid therapy. Serum osteocalcin levels were lower in MCTD patients than in controls. Lower serum oestradiol, testosterone and dehydroepiandrosterone sulphate levels were detected in MCTD patients than in controls. Thus, MCTD may be associated with increased bone loss. Pathogenic factors may include the disease itself, corticosteroid therapy, impaired osteoblast function, and low serum sex hormone levels.