Pituitary-adrenal function in women treated with low doses of prednisone.

In order to assess whether long-term low-dose glucocorticoid administration results in suppression of the hypothalamic-pituitary-adrenal (H-P-A) axis, we examined the response of plasma cortisol to insulin-induced hypoglycemia in 23 women treated with prednisone (5 mg/day) compared with that in 19 untreated women. Basal AM levels of plasma cortisol were unaffected (mean +/- SE, 11.6 +/- 0.9 versus 11.2 +/- 0.7 microgram/dl). The plasma cortisol increment at 609 minutes after insulin-induced hypoglycemia was significantly smaller in the treated group than in the untreated group (6.7 +/- 1.0 versus 11.6 +/- 1.2 microgram/dl, p less than 0.005). Thirteen of 23 women (56.5%) in the steroid-treated group compared to one of 19 (5.3%) in the untreated group, showed a rise in plasma cortisol of less than 6 microgram/dl at 60 minutes. Furthermore, a similar reduction in the increment of plasma cortisol was also found in a subset of 10 women tested both before and during prednisone treatment. These results indicate that the concept that low doses of glucocorticoids are free of suppressive effects on H-P-A function is not justified.