PSAT350 Autoimmune Polyglandular Syndrome Type II Presenting with Hashimoto's Thyroiditis, Diabetes Mellitus Type I and Addison's Disease: A Case Report

A. BACKGROUND/SIGNIFICANCE Autoimmune polyglandular syndrome Type II (APS-II) is a rare polyendocrinopathy with a prevalence of 1 to 2 in 100,000, instigated by immune-mediated destruction of several organs. Knowledge of APS-II is crucial, especially in the early detection of polyglandular disorder among patients with endocrine autoimmunity. B. CASE This case is of a 40-year-old male who initially presented with Grave's disease after showing signs and symptoms of hyperthyroidism, as supported by low thyrotropin (<0.05 uIU/mL; nv: 0.35-4.94) and high free thyroxine levels (2.05 ng/dL, nv: 0.71-1.85). He was maintained on methimazole. Five months following diagnosis, he developed symptoms of Diabetes Mellitus Type 1 (T1DM) as confirmed by high capillary blood glucose, undetectable C-peptide, and positive anti-Glutamic acid decarboxylase. Insulin and rosuvastatin were added on his maintenance medications. Ten months later, he discontinued methimazole and became lost to follow-up. One month after discontinuation, he sought consult again after experiencing symptoms of fatigue, muscle cramps, cold intolerance, forgetfulness, abdominal pain, diarrhea, and episodes of hypoglycemia at home. On examination, he was noted to have hypotension of 80/60 mmHg and skin hyperpigmentation. His random blood sugar was 408 mg/dL. High thyrotropin (57.8777 uIU/Ml, nv: 0.35-4.94), low free thyroxine (0.57 ng/dL, nv: 0.71-1.85), and positive antithyroid peroxidase antibody levels revealed Hashimoto's thyroiditis. Low fasting 8 am serum cortisol (81 nmol/L, nv: 138-635) and low serum cortisol 30 mins (403.85 nmol/L) and 1 hour (542.31 nmol/L, normal response: >550 nmol/L) after adrenocorticotropic hormone stimulation test in addition to the clinical manifestations, supported the diagnosis of Addison's disease. With the combination of Addison's disease, Autoimmune thyroid disease, and T1DM, a diagnosis of APS Type II was made. Management included insulin, prednisone, and levothyroxine. These resulted in significant improvement in the patient's symptoms. He is now clinically well and compliant to regular follow-up. C. LEARNING POINTS/CONCLUSION It is crucial in APS-II management to identify and manage the associated autoimmune disorders to prevent significant morbidity and mortality. Therefore, in the presence of any autoimmune disorder, a high index of suspicion for APS-II is essential. There should be regular follow-up and observation of patients with autoimmune endocrine disorders to ensure early detection of APS-II. Patient health education must include identifying symptoms of the disorders for which they are at high risk. Keywords: APS Type 2, Addison's Disease, DM Type 1, Hashimoto's Thyroiditis Sources of Support: None Conflicts of Interest: None Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.