Endocrine Abstracts

JOINT1504

Introduction: Only five small studies have evaluated the effects of supraphysiologic intravenous methylprednisolone (IVMP) therapy on hypothalamic-pituitary-adrenal (HPA) axis suppression in patients with active moderate-to-severe thyroid eye disease (TED). The standard IVMP regimen consists of 4.5 g administered over 12 weeks (0.5 g weekly for six weeks, followed by 0.25 g weekly for another six weeks).

Aim: To investigate the impact of IVMP therapy on HPA axis function in patients with moderate-to-severe TED.

Methods: This study included adults (>18 years) with active moderate-to-severe TED followed at the Department of Endocrinology and Metabolic Diseases, University General Hospital of Larissa, Greece, (April 2008–July 2024). HPA axis function was assessed using the standard-dose Synacthen test (250 μg synthetic ACTH) 7–10 days after IVMP completion. Serum cortisol levels were measured at baseline and 30- and 60-minutes post-ACTH injection. Adrenal sufficiency was defined as a peak cortisol level ≥18.1 μg/dl (500 nmol/L). Patients receiving glucocorticoids of any route of administration beyond the IVMP regimen or with conditions affecting cortisol-binding globulin were excluded.

Results: Of 127 enrolled patients, 115 were analyzed. the test could not be performed in 12 patients due to drug unavailability (n = 9), severe infection (n = 2), or incorrect dosing (n = 1), leaving 115 patients for analysis. All patients were euthyroid at the time of testing (FT4 range: 0.96–1.67 ng/dl; reference range: 0.93–1.7 ng/dl). Baseline cortisol levels were ≥18.1 μg/dl in 13% of patients, while 93% and 100% achieved ≥18.1 μg/dl at 30- and 60-minutes post-ACTH injection, respectively, indicating intact adrenal function. Notably, all patients with baseline cortisol <5.5 μg/dl achieved peak cortisol levels ≥18.1 μg/dl.

Discussion: Consistent with prior small studies, our findings in a large cohort confirm no evidence of HPA axis suppression following IVMP therapy for TED. Routine HPA function evaluation may not be necessary for TED patients receiving IVMP.