Hypothalamo-pituitary--adrenal (HPA) function was studied using
tetracosactrin and
insulin hypoglycemia tests in eleven asthmatic patients who were receiving or had taken oral
steroids. The patients had been on
prednisone, 5--20 mg/day for 2--17 years. As the dose was reduced they used
beclomethasone inhalation, up to 800 micrograms/day. Seven
insulin hypoglycemia tests were performed when the patients had been off oral
steroids for 15--37 months. Plasma
cortisol responses were normal in all seven, three had subnormal responses of
ACTH. In five patients serial
tetracosactrin and
insulin hypoglycaemia tests were performed during reduction of
steroid dose. Two patterns of recovery of HPA function were observed. In one, both hypothalamo--pituitary and adrenal function seemed to return simultaneously, in the other normal response to
tetracosactrin appeared before that to
insulin hypoglycaemia. One patient had normal
ACTH and
cortisol responses to the stress of a vasovagal attack, but failed to respond to subsequent hypoglycaemia. We conclude that a normal response to
tetracosactrin does not indicate recovery of the HPA axis after stopping prolonged oral
steroid therapy for
asthma, and that patients should continue to carry
steroid therapy cards for at least 5 years after such treatment has been discontinued.