SUN-779 Non-surgical hypoparathyroidism: autoimmune versus idiopathic etiology

Abstract Disclosure: S.S. Mathew: None. B. Cunningham: None. M. Acharya: None. C. sherpa: None. Hypoparathyroidism is a relatively uncommon finding, usually presenting with signs or symptoms of hypocalcemia. About eighty percent of cases are found to be postsurgical. Hypoparathyroidism is important to recognize given its potentially life-threatening effects including seizure, arrythmia, heart failure, and laryngospasm. Here, we present a case of primary hypoparathyroidism likely secondary to autoimmune etiology.A 62-year-old female was admitted to the hospital with necrotizing fasciitis and evaluated by endocrinology for hypocalcemia. Workup revealed low calcium of 6.1 mg/dL with inappropriately low intact parathyroid hormone (PTH) of 3 pg/mL, elevated phosphorus at 6.1 mg/dL, low Vitamin D of 19.4 ng/mL, and low magnesium of 1.7 mg/dL. These findings were consistent with primary hypoparathyroidism. Further evaluation was done to evaluate for features of autoimmune Polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED). There was no history of candidiasis. Thyroid function test was normal. GAD/islet cell/TPO/21 hydroxylase antibody testing were negative. The TTG antibody was also negative. She does have a positive autoimmune history of psoriasis and positive family history of hypocalcemia in parents and siblings. She was treated with calcitriol, magnesium, calcium citrate, and vitamin D supplementation daily. She currently remains asymptomatic.The most common cause of hypoparathyroidism is postsurgical, usually after thyroidectomy. In a minority of cases, other causes can include radiation treatment, autoimmune disease, genetic disorders such as DiGeorge syndrome, or infiltrative disease such as hemochromatosis or malignancy. Many patients with hypocalcemia can be asymptomatic. When patients are symptomatic, common complaints include perioral numbness, distal extremity paresthesia, and tetany. Less specific symptoms may include fatigue, anxiety, prolonged QT interval, or cardiac arrhythmias. Symptoms also depend on the acuity of hypocalcemia, with more pronounced symptoms associated with rapid decline in calcium level. Management of hypoparathyroidism includes treatment with calcium and an active vitamin D analogue. PTH replacement therapy should be considered in patients who are not adequately controlled on conventional therapy.Though workup has thus far been unrevealing for our patient, the primary suspicion remains autoimmune given her significant family history and personal history of psoriasis. She will be monitored clinically for development of any other autoimmune disorders. Presentation: Sunday, July 13, 2025