Newborn screening for congenital adrenal hyperplasia in New Zealand 1994-2013.

Heather NL1, Seneviratne SN, Webster D, Derraik JG, Jefferies C, Carll J, Jiang Y, Cutfield WS, Hofman PL.

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Abstract

Objective: To evaluate the efficacy of national newborn screening for severe congenital adrenal hyperplasia (CAH) in New Zealand over the past 20 years. Methods: Newborn screening for CAH is performed through estimation of 17-hydroxyprogesterone (17-OHP) by Delfia immunoassay. CAH cases diagnosed in the newborn period from 1994-2013 were identified from Newborn Metabolic Screening Programme (NMSP) records. Results: Between 1994 and 2013, 44 neonates (28 females, 16 males) were diagnosed with CAH, giving an incidence of 1:26,727. Almost half (n=21) of newborns with CAH were detected solely via screening (not clinically suspected), including 21% of all affected females. Amongst the group solely ascertained by screening, 17-OHP sampling occurred at a mean age of 3.3 days (range 2-8 days), the duration from sampling to notification was 5.2 days (0-12 days), and treatment was initiated at 12.0 days (6-122). Vomiting was present in 14% of those ascertained by screening, but none had hypotension or collapse at diagnosis. Increasing age at treatment was correlated with a progressive decrease in serum sodium (r=-0.56; p<0.0001) and increase in serum potassium concentrations (r=0.38; p=0.017). Compared to newborns diagnosed by screening alone, those clinically diagnosed were predominantly female (96% vs 29%; p<0.0001), notification occurred earlier (4.8 vs 8.5 days; p=0.002), had higher serum sodium (136.8 vs 130.8 mmol/l; p<0.0001) and lower serum potassium (5.3 vs 6.0 mmol/l; p=0.011) concentrations. Conclusions: Screening alone accounted for nearly 50% cases of CAH detected in the newborn period, including a fifth of affected females, indicating that clinical diagnosis is unreliable in both genders. Symptoms were mild at diagnosis and there were no adrenal crises. This study confirms the benefits of newborn CAH screening.