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Neonatal screening for congenital adrenal hyperplasia
Perrin C. White
Abstract | Congenital adrenal hyperplasia (CAH) caused by steroid 21hydroxylase deficiency occurs in 1:16,0001:20,000 births. If not promptly diagnosed and treated, CAH can cause death in early infancy from shock, hyponatremia and hyperkalemia. Affected girls usually have ambiguous genitalia but boys appear normal; therefore, newborn babies are commonly screened for CAH in the US and many other countries. By identifying babies with severe, saltwasting CAH before they develop adrenal crises, screening reduces morbidity and mortality, particularly among affected boys. Diagnosis is based on elevated levels of 17hydroxyprogesterone, the preferred substrate for steroid 21hydroxylase. Initial testing usually involves dissociationenhanced lanthanide fluorescence immunoassay that has a low positive predictive value (about 1%), which leads to many followup evaluations that have negative results. The positive predictive value might be improved by secondtier screening using DNAbased methods or liquid chromatography followed by tandem mass spectrometry, but these methods are not widely adopted. Cost estimatesfor such screening range from US$20,000 to $300,000 per lifeyear saved. In babies with markedly abnormal screen results, levels of serum electrolytes and 17hydroxyprogesterone should be immediately determined, but the most reliable way to diagnose CAH is measurement of levels of steroid precursors after stimulation with cosyntropin.
White, P. C. Nat. Rev. Endocrinol. 5, 490498 (2009); http://www.nature.com/doifinder/10.1038/nrendo.2009.148
Web End =doi:10.1038/nrendo.2009.148
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