Outpatient adrenocorticotropin (ACTH) stimulation tests can be challenging to interpret due to heterogeneously reported cut-offs. Inpatient stimulation tests present additional challenges due to the presence of acute illness and unreliable coordination of dynamic function testing on a busy inpatient service. This study aims to characterize the use of ACTH stimulation tests in hospitalized patients to determine necessity of testing.
We conducted an inpatient audit of ACTH simulation tests done to rule out adrenal insufficiency between April 2018 to March 2019 at our institution. Normal post-ACTH response was defined as peak cortisol ≥500 nmol/L. Testing was considered inappropriate in patients with normal post-ACTH response who had a serum cortisol ≥250 nmol/L drawn during the same admission prior to stimulation testing. Cut-offs were based on previous analysis of 195 outpatient stimulation tests.
During the one-year study period there were 40 inpatients who had an ACTH stimulation test. Nineteen (48%) were considered unnecessary because patients either had a pre-ACTH serum cortisol ≥250 nmol/L and/or a 0-minute cortisol value just prior to the ACTH stimulation test ≥250 nmol/L. Except for a single instance where the patient was inappropriately on prednisone when basal cortisol was tested, all patients with any pre-ACTH cortisol ≥250 nmol/L had a normal post-ACTH response
Institutions may avoid unnecessary inpatient ACTH stimulation tests by implementing protocols which ensure that basal cortisol levels are drawn and below locally determined cut-offs before proceeding to dynamic testing. To characterize further, a three-year analysis of inpatient ACTH stimulation tests is underway.