Newborn Screening   Congenital Adrenal Hyperplasia (CAH) (Updated 04/30/04) CAH is a family of autosomal recessive disorders characterized by the inability to synthesize cortisol, and in most instances, also the inability to synthesize the salt-retaining hormone, aldosterone. The most common form of CAH (more than 90% of cases) is caused by a deficiency of the adrenal enzyme 21-hydroxylase (21-OH) and is identified by assessing the level of 17-alpha-hydroxyprogesterone (17-OHP) in blood. Depending on the extent of the enzyme deficiency, the disorder presents as either a salt-losing form (75% of cases), or a non-salt-losing form. CAH is the most common cause of ambiguous genitalia in females, and can cause acute life-threatening adrenal crisis in both males and females in the neonatal period. The State of Missouri newborn screening test is for the 21-OH form of CAH. The analyte is serum 17-alpha-hydroxyprogesterone (17-OHP), the metabolic product just prior to the cortisol synthesis step requiring the deficient enzyme 21-OH. The levels of 17-OHP are generally very elevated in both salt-losing and non-salt-losing forms of 21-OH CAH. Levels of < 50 ng/ml are considered normal for a ¡°normal¡± weight infant (2250 grams or greater), and are adjusted to higher levels for low birth weight infants.  Prevalence: 1: 10,000  Analyte Measured: 17 ¦Á-hydroxyprogesterone  Reporting Ranges: Reporting ranges are weight dependent: Weight (gms) 17-OHP Results (ng/ml) Result ¡Ü 1249 ¡Ü 134 Normal 135 - 159 Borderline ¡Ý 160 Presumptive Positive 1250 - 1749 ¡Ü 89 Normal 90 - 134 Borderline ¡Ý 135 Presumptive Positive 1750 - 2249 ¡Ü 64 Normal 65 - 89 Borderline ¡Ý 90 Presumptive Positive ¡Ý 2250 ¡Ü 49 Normal 50 - 89 Borderline ¡Ý 90 Presumptive Positive Feeding Effect: None Timing Effect: False positive 17-OHP results may occur if sample is collected before                       24 hours of age. Premature infants: Because the immature adrenal gland sustains increased plasma concentrations of most adrenal metabolites, including those measured to detect CAH, elevated levels of (17-OHP) are normally found in premature infants. Additionally, the stress of illness commonly experienced by premature infants also stimulates adrenal steroid production. Confirmation: Repeat newborn screen through Missouri Newborn Screening Program. Treatment: Salt losing and non-salt losing diagnosis and treatment should be made by a                   pediatric endocrinologist.