Hypocitraturia Contributing to Nephrolithiasis in a Patient with CYP24A1 Gene Mutation

Objective: There have been several case reports of hypercalcemia due to mutation in CYP24A1, which encodes an enzyme that controls the catabolism of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D to inactive forms. These patients develop nephrolithiasis, nephrocalcinosis, and eventually renal insufficiency. We describe a patient with hypercalcemia and nephrolithiasis due to CYP24A1 mutation with other co-existing factors for renal stone formation. Methods: A literature search was conducted using the PubMed and Google Scholar databases for CYP24A1 mutation and hypercalcemia. Publications were selected based the quality of the data and clinical relevance. Results: CYP24A1 mutation may lead to hypercalcemia, hypercalciuria, and renal stone formation; however, other risk factors for renal stone formation such as urinary citrate, sodium, oxalate, and uric acid levels need to be evaluated. Conclusions: This case highlights the need to evaluate for other renal stone risk factors in patients with CYP24A1 mutation.