Parathyroid hormone and 25-hydroxyvitamin D levels in glucocorticoid-treated patients

Abnormalities in parathyroid hormone (PTH) secretion or vitamin D action or metabolism have been suggested as pathogenetic factors in the bone disease associated with chronic glucocorticoid therapy. We have found normal plasma PTH values in forty-eight adult asthmatic patients on chronic glucocorticoid therapy, twelve asthmatics treated without glucocorticoids and ten adults on short-term, high-dose glucocorticoid therapy for non-asthmatic illnesses. The mean serum 25-OHD level in the glucocorticoid-treated asthmatics was not significantly different from a disease control group of asthmatic patients not on glucocorticoids, but nine such patients had abnormally low 25-OHD levels. Our results indicate that in asthmatic patients on chronic glucocorticoid therapy: (1) PTH and 25-OHD values are usually normal regardless of dose or duration of therapy and (2) there is a subset of patients with low 25-OHD values which may reflect unusual sensitivity to glucocorticoids.