Low Adrenomedullary Function Predicts Acute Illness in Infants With Classical Congenital Adrenal Hyperplasia.

CONTEXT: Youth with classical congenital adrenal hyperplasia (CAH) exhibit abnormal adrenomedullary function with decreased epinephrine levels noted in newborns and young infants. Little is known about how this relates to morbidity during the first year of life. OBJECTIVE: This work aimed to study plasma epinephrine levels in infants with classical CAH and examine the clinical significance of epinephrine deficiency in the first year of life. METHODS: This prospective cohort study comprised participants recruited from a pediatric tertiary care center: 36 infants with classical CAH due to 21-hydroxylase deficiency and 27 age-matched unaffected controls with congenital hypothyroidism. Main outcome measures included plasma epinephrine levels (N = 27), CYP21A2 genotype (N = 15), and incidence of acute illnesses from birth to age 1 year (N = 28). RESULTS: Epinephrine levels in CAH infants independently predicted illness incidence in the first year of life (ß = -0.018, R = -0.45, P = .02) and were negatively correlated with 17-hydroxyprogesterone at diagnosis (R = -0.51, P = .007). Infants with salt-wasting CAH exhibited lower epinephrine levels as newborns than simple-virilizing infants (P = .02). CAH patients had lower epinephrine as newborns than did controls (P = .007) and showed decreases in epinephrine from birth to age 1 year (P = .04). Null genotype was associated with lower newborn epinephrine and more illness in the first year of life, compared to less severe mutation categories. CONCLUSION: Lower epinephrine levels are associated with increased risk of illness among CAH infants. While not currently part of clinical standard of care, measuring epinephrine levels and assessing genotype may help predict acute illness in the first year of life.