Background: Suppression of the adrenal response is an unpredictable consequence of glucocorticoid treatment. To investigate the kinetics of the adrenal response after short-term, high-dose glucocorticoid treatment, we measured the adrenal response to the low-dose (1 microg) corticotropin stimulation test.
Methods: We studied 75 patients who received the equivalent of at least 25 mg prednisone daily for between 5 days and 30 days. After discontinuation of glucocorticoid treatment, 1 microg corticotropin was administered intravenously, and stimulated plasma cortisol concentrations were measured 30 min later. In patients with a suppressed response to 1 microg corticotropin, the test was repeated until stimulated plasma cortisol concentrations reached the normal range.
Findings: The adrenal response to 1 microg corticotropin was suppressed in 34 patients and normal in 41. Subsequent low-dose corticotropin tests showed a steady recovery of the adrenal response within 14 days. In two patients, the adrenal response remained suppressed for several months. There was no correlation between plasma cortisol concentrations and the duration or dose of glucocorticoid treatment.
Interpretation: Suppression of the adrenal response is common after short-term, high-dose glucocorticoid treatment. The low-dose corticotropin test is a sensitive and simple test to assess the adrenal response after such treatment.