Hypocalciuric Hypercalcemia Presenting as Neonatal Rib Fractures: A Newly Described Mutation of the Calcium-sensing Receptor GeneNyweide, Kristin MD*; Feldman, Kenneth W. MD*†; Gunther, Daniel F. MD*‡; Done, Stephen MD*§; Lewis, Charlotte MD, MPH*†; Eenwyk, Claire Van MD∥Pediatric Emergency Care: November 2006 - Volume 22 - Issue 11 - p 722-724 doi: 10.1097/01.pec.0000238747.19477.d3 Illustrative Cases Buy SDC Abstract Author InformationAuthors Article MetricsMetrics A 2-week-old infant presented with bilateral rib fractures, hypercalcemia, and subperiosteal bone erosions. Parathyroid hormone levels were elevated and urine calcium low. Her parent's laboratory test results were normal. Gene sequencing revealed a new mutation of the calcium-sensing receptor gene, causing severe neonatal hyperparathyroidism, a variant of hypocalciuric hypercalcemia. This is a rare cause of neonatal hyperparathyroidism and nonabusive fractures. Departments of *Pediatrics, †General Pediatric, ‡Endocrine, and §Radiology, Divisions of the University of Washington School of Medicine and the Children's Hospital and Regional Medical Center, Seattle, WA and ∥Virginia Commonwealth University Health Services, Richmond, VA. Address correspondence and reprint requests to Kenneth Feldman, MD, Odessa Brown Children's Clinic, 2101 East Yesler Way, Seattle, WA 98122. E-mail: firstname.lastname@example.org. © 2006 Lippincott Williams & Wilkins, Inc.