Year: 2025
Type: article
Abstract: Disclosure: L. Alemu: None. R. Jain: Amgen Inc, Ascendis Pharma - Investigator, Amolyt Pharma - Investigator, MBX Biosciences - Investigator, Guidepoint Consulting - Consulting, Atheneum - Consulting. Gestational hypercalcemia is an uncommon complication of pregnancy, and most often due to primary hyperparathyroidism. We present an unusual case of hypercalcemia in pregnancy, later found to be related to heterozygous pathologic variant in the CYP24A1 gene. In 1999, a 35-year-old P2G3 patient with no medical history was induced at 37 weeks after diagnosis of pre-eclampsia. On one week follow up she was incidentally found to have a serum calcium level (Ca) of 15.1mg/dl with her only symptom being fatigue. She was admitted and found to have parathyroid hormone (PTH) <7, received fluids, diuresis and steroids for empiric granulomatous disease suppression with improvement of Ca to 11 mg/dL and patient was discharged. Despite steroid treatment, Ca continued to rise to 15.3 mg/dL on outpatient follow up, and she was re-admitted 17 days post-partum. On admission she was essentially asymptomatic, and was treated with fluids and Pamidronate 30 mg IV. Patient lacked symptoms concerning for malignancy, normal SPEP/UPEP not concerning for myeloma, and urine Ca of 347 mg/24 hours. Ca down trended following Pamidronate administration and was normal at outpatient endocrinology 1 month follow up, where she was diagnosed with lactation-induced hypercalcemia.In the 24 years following, patient followed with a nephrologist for hypercalciuria and was started on hydrochlorothiazide 50 mg daily. Urine calcium decreased to 165-257 mg/24 hr and due to lack of a history of kidney stones after 20 years, the thiazide was discontinued in 2020. In 2024 she was referred to endocrinology for concerns of hyperparathyroidism. She reported calcium got to as high as 10.6 mg/dL when she started taking Vitamin D3 2000 IU supplements. On review of labs from her 1999 admission she notably had inappropriately high 1,25 dihydroxy vitamin D (82 pg/mL, reference 15-60 pg/mL), PTH<7 pg/mL, Ca 15.3 mg/dL. Given persistent hypercalciuria, there was concern for CYP24A1 pathologic variant. Genetic testing was sent and returned positive for CYP24A1 heterozygous mutation c.1226T>C (p.Leu409Ser). A repeat 24-hour urine Ca was borderline at 246 mg/24 hrs. She was restarted on hydrochlorothiazide 25 mg. A DXA done at this time revealed a lowest T-score of -1.9 and Z-score of -0.6 at the total hip. Here, we present a case of gestational hypercalcemia from heterozygous pathologic variant of CYP24A1. Gestational hypercalcemia is an uncommon disorder of pregnancy related to increased mobilization of calcium in the mother to meet the calcium requirements of the fetus. This case demonstrates the importance of identifying an underlying cause- while our patient’s severe hypercalcemia did not recur, she continued to have persistent hypercalciuria for over 20 years. Treatment with a thiazide diuretic for years likely helped prevent kidney stones and reduced the severity of bone disease. Presentation: Sunday, July 13, 2025
Source: Journal of the Endocrine Society
Authors: Leah Alemu, Rajesh Jain
Institution: University of Chicago
Language: English
Subfield: Nephrology
Field: Medicine
Domain: Health Sciences
Open Access status: gold
Estimated APC paid: $3,255
OpenAlex ID: W7093337428
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