Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + • Benign condition of chronic, nonprogressive hypercalcemia with mildly elevated intact parathyroid hormone• Family history of hypercalcemia, especially in children• Etiology is a defect in the gene coding for the calcium sensing receptor; autosomal dominant transmission• Essentially is an elevation in the calcium set point• Often discovered incidentally with screening laboratory studies +++ Symptoms and Signs + • Usually none• May have polyuria and polydipsia or thirst +++ Laboratory Findings + • High serum calcium• Normal or mildly elevated intact parathyroid hormone level• Low urinary calcium• Urinary calcium clearance to creatinine clearance ratio of < 0.01• Possibly high serum magnesium level +++ Rule Out + • Primary hyperparathyroidism + • Complete history (including family) and physical exam• Direct genetic testing for calcium sensing receptor defect + • None required• Operative neck exploration does not alleviate this condition (with the exception of total parathyroidectomy, and surgically induced permanent hypoparathyroidism)• Genetic counseling important; offspring homozygous for mutation have severe neonatal hyperparathyroidism, which is potentially lethal +++ References ++Pollak MR et al. Mutations in the human Ca-sensing receptor gene cause familial hypocalciuric hypercalcemia and neonatal severe hyperparathyroidism. Cell. 1993;75:1297. [PubMed: 7916660] ++Marx SJ et al. The hypocalciuric or benign variant of familial hypercalcemia: clinical and biochemical features in fifteen kindreds. Medicine. 1998;60:397. ++Egbuna OI. Brown EM. Hypercalcaemic and hypocalcaemic conditions due to calcium-sensing receptor mutations. Best Practice & Research in Clinical Rheumatology 2008, 22(1):129-48. [PubMed: 18328986] Your MyAccess profile is currently affiliated with '[InstitutionA]' and is in the process of switching affiliations to '[InstitutionB]'. Please click ‘Continue’ to continue the affiliation switch, otherwise click ‘Cancel’ to cancel signing in. Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Username? Forgot Password? Sign in via OpenAthens Sign in via Shibboleth