Abstract
Disclosure: B. Cardakli: None. S. Clare: None. A. Mathew: None. M. Kutahyalioglu: None. Background: Polyglandular Autoimmune Syndrome Type II (PAS-II), also known as Schmidt Syndrome, is a rare genetic condition characterized by multiple endocrine dysfunctions most commonly including type 1 diabetes (T1D), adrenal insufficiency, and autoimmune thyroid disease. Uncontrolled hyperthyroidism and adrenal insufficiency can lead to recurrent diabetic ketoacidosis (DKA) in patients with T1D. Clinical Case: A 24-year-old female with a history of T1D was admitted for DKA. Diagnosed at age four, she managed her condition well, with rare DKA admissions previously. She has a strong family history of autoimmune disorders, including T1D, polymyositis, celiac disease, systemic lupus erythematosus, and rheumatoid arthritis. She has been using an insulin pump for the past four years without malfunctions and has consistently adhered to her diabetes therapy. Over the past 12 months, she experienced persistent fatigue, nausea, frequent hypoglycemia, and low appetite, resulting in six DKA admissions, with two occurring just one week apart—unusual given her prior history. During the first admission of the year, she was diagnosed with autoimmune hyperthyroidism. Her thyroid peroxidase antibodies were elevated, and although initially negative, her thyroid-stimulating immunoglobulin became positive three months later. Methimazole was prescribed, with dosage adjusted based on thyroid function tests. Adrenal insufficiency was also suspected at the same admission and confirmed with a positive cosyntropin stimulation test (CST), though her 21-hydroxylase antibody was negative. She began hydrocortisone treatment, discontinued six months later after a negative CST. In her two most recent admissions, uncontrolled hyperthyroidism was suspected to trigger DKA, alongside recurring adrenal insufficiency after common DKA causes were ruled out. Screening for other autoimmune diseases showed normal vitamin B12 levels and a pituitary function panel, including prolactin, IGF-1, LH, FSH, and estradiol, with a negative ANA test. However, she tested positive for celiac disease amidst iron deficiency anemia and vitamin D deficiency. The diagnosis of PAS-II was based on the presence of T1D, autoimmune thyroid disease, and Addison's disease. Her recurrent DKA episodes over the year are attributed to the complex interplay of developing autoimmune disorders, exacerbated by uncontrolled thyroid disease and intermittent adrenal insufficiency. Conclusion: This case highlights the critical importance of considering PAS-II in patients with T1D who present with unexplained DKA, especially those with a strong family history of autoimmune diseases. Early identification through comprehensive screening can aid in prompt management and potentially prevent recurrent episodes. Presentation: Saturday, July 12, 2025