Background/Purpose: Adrenal insufficiency is frequently neglected and underappreciated complication of systemic glucocorticoid therapy. We aimed to evaluate the prevalence of glucocorticoid induced adrenal insufficiency in giant cell arteritis (GCA).

Methods: We analysed adrenal function data in a cohort of GCA patients (51 (67.1%) females, median (IQR) age 72.9 (66.3-77.4) years) in whom a discontinuation of methylprednisolone therapy was planned. Adrenal function was tested by Corticotropin (Synacthen®) stimulation test (CST). To perform the CST, methylprednisolone was substituted with hydrocortisone (20mg qd in three divided doses) for one to four weeks before the test. Adrenal insufficiency was defined as cortisol level < 450 nmol/l measured 30 minutes after the corticotropin injection; additionally, the result of the CST was defined as borderline when the cortisol level 30 minutes after corticotropin injection was between 450 nmol/l and 500 nmol/l.

Results: Adrenal function was tested in 76 GCA patients before definite methylprednisolone withdrawal (after a median 13.5 (12.9 – 24.6) months of glucocorticoid therapy). The mean (SD) methylprednisolone dose, prior to substitution with hydrocortisone and subsequent CST, was 3.7 (0.9) mg. Adrenal insufficiency was detected in 37/76 patients (48.7%); additionally, 10/76 patients (13.2%) had a borderline CST result. Twenty-two patients with either adrenal insufficiency or borderline CST result, had a repeated CST after a median (IQR) 11.6 (8.1; 13.3) months. Adrenal insufficiency persisted in 12/22 (54.5%) patients and was borderline in one patient (4.5%). In 9/22 (40.9%) patients adrenal function recovered meanwhile. A third CST was performed in 6/13 patients with abnormal second CST after median (IQR) 8.3 (6.9; 12.6) months. Adrenal function recovered in one patient, while insufficiency persisted in the remaining 5 patients.

Conclusion: Adrenal insufficiency is frequent and potentially long-lasting glucocorticoid induced adverse event in GCA patients.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/adrenal-insufficiency-after-glucocorticoid-treatment-of-giant-cell-arteritis/