Weber J, Tanawattanacharoen VK, Seagroves A, et al. - In infants with congenital adrenal hyperplasia (CAH), lower epinephrine levels are linked to an increased risk of illness. Measurement of epinephrine levels and genotype assessment may assist predict acute illness in the first year of birth, despite the fact that they are not now part of the standard of care.

• This prospective cohort study involved 36 infants with classical CAH due to 21-hydroxylase deficiency and 27 age-matched unaffected controls with congenital hypothyroidism.

• Epinephrine levels in CAH infants predicted illness incidence independently in the first year of life and were negatively associated with 17-hydroxyprogesterone at diagnosis.

• As newborns, infants with salt-wasting CAH had lower epinephrine levels than simple-virilizing infants.

• CAH patients had lower epinephrine levels as infants than controls, and epinephrine levels decreased from birth to 1 year.

• In comparison to less severe mutation categories, null genotype was associated with decreased newborn epinephrine and higher sickness in the first year of life.