SAT224 Nonsurgical Hypoparathyroidism: 40 Years After Diagnosis

Disclosure: L.I. Kaplan: None. A. Yuen: None. P.D. Greenberg: None. Background: The majority of cases of hypoparathyroidism occur after neck surgery. The most common nonsurgical cause is autoimmune, either in isolation or part of Autoimmune Polyglandular Syndrome Type 1. Hypomagnesemia is a functional cause. Hypoparathyroidism can occur as part of genetic syndromes that include congenital anomalies, short stature and developmental delay. Non-syndromic genetic etiologies including Autosomal Dominant Hypocalcemia type 1 (ADH1), a gain of function mutation in the calcium sensing receptor (CaSR) that can present in infancy, childhood or adulthood with hypocalcemia (50% symptomatic), hypercalcuria (10%) and basal ganglia calcification (35%). For ADH1, targeted therapies are being developed. Clinical Case: A 90-year-old male was diagnosed with hypoparathyroidism at age 50 when he presented with hand cramping and was found to have hypocalcemia with low PTH. He was started on calcitriol and calcium supplementation. Many years later he started following at our endocrine clinic. Past medical history includes prostate cancer treated with radiation and androgen deprivation therapy, HTN, and pre-diabetes. He has no history of neck surgery, other endocrinopathies, candidiasis, vitiligo or congenital anomalies. He has no family history of hypocalcemia and has two children without calcium abnormalities. His DEXA shows stable +T scores in LS spine and bilateral hips. He has not had brain imaging. Nephrocalcinosis was not reported on renal ultrasound. More than 10 years ago, he presented with severe hypercalcemia, acute renal failure (Ca 13.5 mg/dl, Cr 6.0mg/dl, Phos 5.5mg/dl) and ureteral stones after taking over the counter calcium supplements in excess. He underwent stone removal with return to baseline renal function. Subsequently, he underwent knee replacement surgeries and required IV calcium until he was able to swallow pills. Since this time, he has been managed on calcitriol, calcium carbonate, vitamin D3, and chlorthalidone with close follow up for adjustment of regimen to target Ca 8.0-8.5 mg/dl. He has not had a recurrence of severe hypercalcemia, hyperphosphatemia or nephrolithiasis. He feels well and lives at home with his wife. Lab values over the past 10 years are as follows: Ca 8.1-10.6 mg/dl (8.5-10.5), Alb 4.0-4.6 g/dl (3.5-5.4), Phos 4.3-5.5 mg/dl (2.8-4.5), Mg 1.7-1.9 mg/dl (1.3-2.1), K 3.7-4.4 mEq/L (3.6-5.2), Cr 1.0-1.5 mg/dl (0.5-1.3), PTH 0.00-1.4 pg/ml (10-55), 25 OH Vit D 18-58 ng/ml (32-100), 1,25 OH Vit D3 25.5-37.2 pg/ml (19.9-79.3), 24hr Urine Ca 162- 384 mg/24 hrs (50-400). Clinical lessons: Chronic hypoparathyroidism can be well managed with close follow up and frequent lab monitoring. This patient should be referred for genetic testing, particularly to look for ADH1 mutation in the CaSR gene as targeted treatments are being developed. His children should be tested for any mutations found in him. Presentation: Saturday, June 17, 2023