ESPE Abstracts

SLC34A1 encodes renal sodium-phosphate cotransporter 2A. It has been identified as being a part of the etiology of idiopathic infantile hypercalcemia. We report a case of a 1-month old girl, initially hospitalized due to perinatal detection of nephrocalcinosis. Blood tests showed hypercalcemia, hypophosphatemia, hypercalciuria and increased 1,25-(OH)2D3. Renal ultrasound revealed medullary nephrocalcinosis. An abnormality in vitamin-D metabolism was suspected and genetic testing was performed. This revealed the patient to be compound heterozygous for novel (likely) disease-causing mutation (p.Gly446Asp, p.Arg495Cys) in the SLC34A1 gene. No mutations were found in CYP24A1. The hypercalcemia normalized following a calcium depleted diet and discontinuation of vitamin-D supplementation without phosphate supplementation. But hypercalciuria was wax and wane. Increased awareness of the typical symptoms of hypercalcemia, such as anorexia, polydipsia, vomiting and failure to thrive, is of utmost importance in diagnosing IHH early and preventing long-term complications such as nephrocalcinosis. Further identification of as many disease-causing mutations in the SLC34A1 gene as possible can help identification of predisposed individuals in whom vitamin-D supplementation should be reconsidered