Intestinal calcium absorption and parathyroid hormone secretion in asthmatic patients on prolonged oral or inhaled steroid treatment.

A secondary hyperparathyroidism resulting from decreased intestinal calcium (Ca) absorption has been proposed as a contributory factor to glucocorticoid-induced osteoporosis. Inhaled steroids do not usually suppress adrenal gland function unless daily doses above 1,500 microgram are used. A recent study, however, has shown a reduced total body calcium in patients on regular beclomethasone treatment. In theory, osteopenia in these patients could be due to a direct effect of inhaled steroids on bone or due to an impaired intestinal calcium absorption. In this study, Ca absorption and parathyroid hormone (PTH) secretion were evaluated in three groups: 1) asthmatics on continuous oral and inhaled steroid treatment (11.3 +/- 4.4, range 5-33.5 mg.day-1 prednisone and 660 +/- 265, range 400-1,600 microgram.day-1 beclomethasone, respectively); 2) asthmatics on regular beclomethasone therapy (585 +/- 210, range 400-1,200 microgram.day-1); and 3) healthy subjects. The prevalence of vertebral fractures was evaluated by a spinal X-ray. No differences were found in either Ca absorption or PTH serum levels between asthmatics and healthy subjects (analysis of variance-ANOVA). Vertebral fractures were significantly more frequent in patients from group 1 (14 of 25) than in those from group 2 (2 or 25). We conclude that both prolonged oral steroid treatment and inhaled steroids, at doses lower than 1,600 microgram.day-1 do not cause Ca malabsorption, and that hyperparathyroidism does not contribute to osteoporosis in these patients.