PREDICTING RECOVERY OF THE HYPOTHALAMIC-PITUITARY-ADRENAL AXIS AFTER PROLONGED GLUCOCORTICOID USE

Prolonged exposure to glucocorticoids lead to hypothalamic-pituitary-adrenal (HPA) axis suppression that recovers after cessation of treatment. We aimed to identify the predictive factors for HPA axis recovery after prolonged glucocorticoid use.

Retrospective review of patients who had undergone first short Synacthen test (SST) to assess HPA axis recovery after prolonged use of glucocorticoids.

A total of 61% (20/33) of patients had adequate SST response at a median time of 2 years after diagnosis of adrenal insufficiency. Those who had adequate response during SST had higher ambulatory early morning cortisol ( P<.01), shorter duration of exposure to glucocorticoids ( P = .01), and lower final cumulative hydrocortisone replacement dose ( P = .03). Age, gender, body mass index, indications for glucocorticoid use, and basal adrenocorticotropic hormone levels were not predictive of HPA axis recovery. On multivariate analysis, ambulatory early morning cortisol was the only independent predictor of adequate SST response (odds ratio, 1.02; 95% confidence interval, 1.01 to 1.04; P = .02). Using receiver operating characteristic curve analysis, ambulatory early morning cortisol of 8.8 μg/dL predicted a positive SST response with a sensitivity of 70% and specificity of 93%.

Early morning ambulatory cortisol could be used to decide on timely SST in order to prevent complications from unnecessary replacement with glucocorticoids.

ACTH = adrenocorticotropic hormone; BMI = body mass index; CV = coefficient of variation; HPA = hypothalamic-pituitary-adrenal; SST = short Synacthen test.