PSAT054 Isolated ACTH Deficiency in a Patient on Epoprostenol

INTRODUCTION: Epoprostenol is a prostacyclin analog used to treat severe pulmonary arterial hypertension (PAH). Endocrine abnormalities in patients on epoprostenol have been reported, most commonly autoimmune thyroid dysfunction. CASE DESCRIPTION: A 36-year-old woman with weight loss and dyspnea on exertion was diagnosed with pulmonary artery hypertension following right heart catheterization. Her symptoms initially improved after starting IV epoprostenol. Over the following two years, she experienced weight loss and anorexia. Due to concerns that her symptoms were caused by epoprostenol, her dose was reduced. After new-onset tremors and palpitations, thyroid studies were checked demonstrating TSH <0.01 (previously normal) and total T4 18.69 with anti-thyroid peroxidase >900.0 (≤8.9 IU/mL). Repeated thyroid studies 4 weeks later showed transition to the hypothyroid phase of Hashimoto's thyroiditis with TSH 6.65 and total T4 3.21. She was prescribed 50 mcg levothyroxine daily. Despite normalization in thyroid function, she continued to lose weight over the next year with ongoing nausea and anorexia unchanged by decreases in epoprostenol dosing. Her weight dropped to 76 lbs and she was admitted for further work-up. Repeat thyroid studies were normal but cortisol was <1.0 ug/dL and ACTH was <1.1 (7.2 - 63.3 pg/mL). Remainder of pituitary hormonal evaluation showed normal FSH & LH and low IGF-(63 ng/mL, Z-score -2.9). She denied recent steroid use. MRI head was normal as was CT of the adrenal glands. Her symptoms rapidly improved after initiation of 15 mg hydrocortisone. Repeat RHC showed marked improvement in hemodynamics. DISCUSSION: The association between autoimmune thyroid disease and PAH has been relatively well described and hypothyroidism seems to be more prevalent than hyperthyroidism. We found just 3 other cases of adrenal insufficiency in patients on epoprostenol. The mechanism for endocrinopathies in this population is unclear. In addition to their effects on endothelial cells, PGI2 analogs have been noted to have a role in T helper cell differentiation. Th17 cells are implicated in autoimmune diseases like multiple sclerosis, so prolonged use of PGI2 analogs may cause systemic inflammation and trigger autoimmunity. It is important for clinicians to be aware that diagnosing adrenal insufficiency in this population can be difficult as the side effects of epoprostenol (lightheadedness, nausea, vomiting, weight loss, and anorexia) are similar to the symptoms of adrenal insufficiency. With this in mind, it is important that adrenal insufficiency remains high on the differential diagnosis of patients presenting with such symptoms when on epoprostenol treatment to prevent delays in diagnosis. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.