The presentation of congenital adrenal hyperplasia in an unscreened population.

Background: The aim of this study was to describe the incidence and spectrum of early clinical presentations of congenital adrenal hyperplasia (CAH) in an unscreened population.

Methods: A national retrospective observational study was undertaken to identify all children diagnosed with CAH in the Republic of Ireland, between January 2005 and December 2019. Reporting clinicians completed anonymized clinical questionnaires.

Results: There were 103 cases of CAH reported and 69 cases met the study inclusion criteria. The estimated annualized incidence of CAH in the Republic of Ireland was 1:14,754 or 0.07 cases per 1,000 live births. Forty-seven children presented clinically in the first six months of life, but only 17 of these had a confirmed diagnosis by day 10. Of these early presentations, there were 28 infants with salt-wasting, 15 females presented with virilized genitalia and four infants were detected due to a family history of CAH. Female infants presented at a median age of 0 days [IQR 0-1] and males at 14 days [IQR 9-21]. Seventy-eight percent of salt-wasting presentations occurred after day 10. Delays in clinical presentation, biochemical diagnosis and treatment initiation were identified.

Conclusions: The incidence of CAH is higher in Ireland than in other unscreened populations. In the absence of screening, clinicians should be aware of the possibility of CAH and appropriate investigations should be urgently requested. Life-threatening salt-wasting is the most frequent clinical presentation and many cases could be detected prior to decompensation if newborn screening were introduced.