SCREENING FOR HYPOTHALAMO-PITUITARY-ADRENAL AXIS SUPPRESSION IN ASTHMATICS TAKING HIGH-DOSE INHALED CORTICOSTEROIDS

High dose inhaled corticosteroids may cause suppression of the hypothalamo-pituitary-adrenal (HPA) axis. Several tests are available to screen for this suppression but it is not clear which is the most useful. HPA function was assessed in 78 adult asthmatics inhaling long-term, high dose (median 1600 μg; range 1200–2650 μg) beclomethasone dipropionate (n = 69) or budesonide (n = 9). Screening tests performed in all patients were 9 am serum cortisol, short tetracosactrin test and 24-h urine free cortisol excretion. Eleven patients also underwent insulin stress tests. Subnormal results were: 9 am cortisol < 190 nmol l−1; urine free cortisol < 80 nmol 24h−1; rise in cortisol in response to tetracosactrin or hypoglycaemia < 200 nmol l−1 and/or achieved cortisol < 500 nmol l−1. HPA suppression (defined as subnormal results of at least two of the three initial tests and/or subnormal response to hypoglycaemia), was found in 16 patients. In the 11 patients who underwent insulin stress tests, results of all initial tests were normal in three, one test was abnormal in three and two tests were abnormal in four patients. All three tests were abnormal in the remaining patient. The response to hypoglycaemia was normal in the three patients whose screening tests were all normal; HPA suppression was present in seven patients and one patient had a borderline result. Close correlation was observed between the maximum cortisol during hypoglycaemia and both urine free cortisol (rs =0·84; P =0·001) and post-tetracosactrin cortisol (r =0·75; P <0·01). One patient with persistently low urine cortisol had a normal response to insulin stress when the morning dose of beclomethasone dipropionate was omitted, but marked suppression when it was taken. The short tetracosactrin test and urine free cortisol were equally useful as screening tests (sensitivity 87%; specificity > 95%); 9 am cortisol was much less sensitive. Measuring 24-h urine free cortisol excretion is a simple, sensitive way of screening for clinically important hypothalamo-pituitary-adrenal suppression from high dose inhaled corticosteroids and avoids the risk of hypersensitivity reactions to tetracosactrin. © 1991, Baillière Tindall All rights reserved. All rights reserved.