FRI258 A Diagnostic Journey To Autoimmune Polyendocrine Syndrome Type 2

Disclosure: S. Amankwah: None. H.K. Driscoll: None. C. Muojieje: None. M. Sanati: None. Background: Approximately 50-65% of patients with autoimmune adrenal insufficiency have one or more autoimmune endocrine disorders. This case demonstrates the importance of considering autoimmune polyendocrine syndrome (APS) when a patient presents with more than one autoimmune endocrine disorder. Case: A 29-year-old woman with history of idiopathic intracranial hypertension, hypothyroidism on levothyroxine 50 mcg daily, endometriosis, and chronic migraines complained of fatigue, word finding difficulty, misspeaking of words, and staring spells. An MRI of the brain w+wo IV contrast revealed hypo-enhancing appearance of the pituitary gland. The patient was referred to endocrinology by neurology. Hormonal work up was performed checking for prolactin, ACTH, morning cortisol, TSH, Free T4, FSH, LH, IGF-1 and a serum chemistry panel. Thyroid antibodies were also ordered to help understand the etiology of her hypothyroidism. Pituitary hormones were normal except elevated TSH and borderline low serum cortisol. Subsequently a co-syntropin stimulation test resulted in inadequate cortisol rise. ACTH level measured inappropriately low normal. The patient then started steroid replacement therapy. Thereafter, 21-hydroxylase antibodies, serum renin and aldosterone were checked to screen for Addison Disease. Her 21-hydroxylase antibody was positive, aldosterone level low, and renin elevated pointing to autoimmune adrenalitis etiology. Her thyroid antibodies were also positive indicating autoimmune thyroid disease. Considering these results, the condition of APS came into question. Hence, the patient was screened for type 1 diabetes mellitus which was positive for glutamic acid decarboxylase 65 antibody but negative for insulin and pancreatic islet cell antibodies. Her hemoglobin A1c was 5.0%. Due to her history of gluten intolerance, she was screened for celiac disease which was negative for t-Transglutaminase antibody. The patient’s fatigue improved on steroid replacement therapy. She became euthyroid after increasing her levothyroxine dose to 75 mcg daily, and repeated MRI a year later did not show pituitary abnormalities. Discussion: APS type 2 is a polygenic inherited disorder associated with HLA-DR3 and DR4 that affects adult females more than males. The syndrome is characterized by type 1 diabetes mellitus, autoimmune thyroid disease and Addison disease. Associated nonendocrine autoimmune syndromes include celiac disease, pernicious anemia, and atrophic gastritis. These characteristics overlap with APS type 1 except for autoimmune thyroid disease that presents with type 2. It should be noted that thyroxine therapy can precipitate a life-threatening Addison crisis in a patient with untreated adrenal insufficiency and hypothyroidism. Therefore, it is necessary to evaluate adrenal function in all hypothyroid patients in whom APS is suspected. Presentation: Friday, June 16, 2023