ESPE Yearbook of Paediatric Endocrinology

J Pediatr Endocrinol Metab 2019; 32(3): 253–258. DOI: 10.1515/jpem-2018-0342

• 44,360 neonates were screened for CAH as part of a pilot screening programme in Beijing.

• In this prospective study, a CAH incidence of 1:7393 was found, and the most common 21 OHase mutation was c.293-13C/A>G.

The authors describe the results of a pilot neonatal screening program for congenital adrenal hyperplasia (CAH) in Beijing. Six neonates with CAH were identified (five of them with severe salt wasting), corresponding to an incidence of 1:7393. Although the authors state that this incidence is higher than the national average, this estimate should be taken with caution as the number of patients enrolled in the study was relatively small (n=44,360), meaning that the 95% confidence interval of the incidence is very large (1:3450 to 1:33,300). This is a reminder that studies assessing incidence for a relatively uncommon disease need to be appropriately powered.

The authors acknowledge two weaknesses of the screening process that illustrate the practical difficulties of developing a newborn screening program for CAH in a country where many families live far from hospitals. First, more than 25% of the neonates with an elevated 17OHP could not be contacted for follow up, meaning that their incidence of CAH may be underestimated (although the majority of those who could not be recalled had relatively lower 17OHP values). Second, the neonates with a positive screening test could be seen in clinic for retesting only within 13 to 83 days after the screening test. As a consequence, all neonates with salt wasting CAH had already presented with severe hyponatremia and hyperkaliemia at the time of diagnosis. The authors of this important work are already working on an improved screening process with a shorter turnaround time, involving faster transportation and processing of the samples.