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Abstract: FR-PO854

Neither Infantile nor Idiopathic: A Challenging Case of Hypercalcemia During Pregnancy

Session Information

Category: Women's Health and Kidney Diseases

  • 2200 Women's Health and Kidney Diseases


  • Magliulo, Eric, University of Nebraska Medical Center, Omaha, Nebraska, United States
  • Aslam, Saher, University of Nebraska Medical Center, Omaha, Nebraska, United States
  • Hawkins, Jay L., University of Nebraska Medical Center, Omaha, Nebraska, United States

Idiopathic Infantile Hypercalcemia (IIH) Type 1 is a rare cause of hypercalcemia presents both in infancy and in adulthood. Autosomal recessive mutations in the CYP24A1 gene, which encodes for the 24-hydroxylase enzyme, were recently identified in patients diagnosed with IIH Type 1. A deficiency or loss of function in this enzyme leads to reduced metabolism of activated vitamin D. Here we present a case of a patient presenting with hypercalcemia, hypertension, and nephrocalcinosis during pregnancy.

Case Description

A 34 year old woman G3P0303 with a history of three pregnancies complicated by hypercalcemia and pre-eclampsia with severe features was referred to Nephrology for evaluation of persistent post-partum hypercalcemia. During her most recent pregnancy, she was hypertensive with a total serum calcium ranged from 9.9 - 12.7 mg/dL. Post-partum, she was initiated on nifedipine, hydralazine, and enalapril. Initial labs were consistent with PTH-independent hypercalcemia with an inappropriately normal serum 1,25 dihydroxy vitamin D. Work up for a granulomatous disease process was negative. Imaging revealed bilateral medullary calcinosis. 24 hour stone analysis showed an increased risk for formation of calcium phosphate stones. A 25 Hydroxyvitamin D:24,25 Dihydroxy-vitamin D ratio could not be calculated as 24,25-Dihydroxy-vitamin D was below the limit of quantification. Genetic testing confirmed the presence of compound heterozygous mutations in the CYP24A1 gene.


A deficiency in the 24-hydroxylase enzyme can manifest in adulthood as hypercalcemia, hypertension, and nephrocalcinosis, often in the setting of pregnancy. Given the rarity of this genetic disease, diagnosis is often delayed. Initial laboratory work up often reveals hypercalcemia, suppressed parathyroid hormone, and normal to mildly elevated 1,25 dihydroxy-vitamin D. Diagnosis requires either genetic testing or an elevated 25 Hydroxyvitamin D:24,25 Dihydroxy-vitamin D ratio, often greater than 80. In our case, the patient developed recurrent gestational hypercalcemia and hypertension. As a result of a delayed diagnosis, measures had not been taken to avoid excess vitamin D and calcium supplementation. This case highlights the importance of pursuing the diagnosis of 24 hydroxylase deficiency in patients that present with hypercalcemia and hypertension in the setting of pregnancy.