The low-dose (1 μg) adrenocorticotropin stimulation test in kidney and kidney-pancreas transplant patients: A potential guideline for steroid withdrawal

Chronic steroid treatment is known to impair the hypothalamic-pituitary adrenal axis (HPA) but the need to assess HPA function prior to withdrawal of steroid therapy in post-transplant patients has not been uniformly accepted. We evaluated the status of the HPA axis in 48 kidney or kidney-pancreas transplant patients who were considered for possible discontinuation of glucocorticoid therapy using a recently validated dynamic test of HPA integrity, the low-dose (1 μg) adrenocorticotropin (ACTH) test. HPA suppression was detected in 29 (60%) of the patients, four of which had severe hypoadrenalism prohibitive of steroid withdrawal. Neither the duration of steroid treatment nor 8:00 AM serum cortisol was a useful marker of hypoadrenalism. 8:00 AM cortisol in subjects with normal HPA reserve and subjects with partial hypoadrenalism overlapped considerably but levels < 5 μg/dL were indicative of severe hypoadrenalism. Pre-withdrawal diagnosis of partial hypoadrenalism allowed the identification of subjects requiring no further steroid replacement under regular daily circumstances. However glucocorticoid supplementation was prescribed in the event of stress such as infection, exceptional effort, trauma or surgery. Individuals with partial HPA impairment, but not patients with severe HPA suppression, improved upon retesting 3 months later. Patients exhibiting normal response to 1 mcg ACTH enjoyed an uneventful course following steroid withdrawal. Since hypoadrenalism is extremely common in post-transplant patients, we recommend the use of the low-dose ACTH test as a convenient method to identify patients with various degrees of hypoadrenalism prior to steroid withdrawal.