[Congenital adrenal hyperplasia newborn screening: Rio de Janeiro experience]

To determine the 17OH progesterone (17OHP) levels in the neonatal screening for Congenital Adrenal Hyperplasia due to 21 hydroxylase deficiency (CAH-21OHD).

The evaluation was performed using 76,360 paper filter samples, obtained from newborn screening in Rio de Janeiro from June 1992 to December 2000. The 17OHP were assayed by fluoroimmunoassay method using the blood collected onto filter paper cards. The cut-off level was 10 ng/mL. The infants with 17OHP levels above this cut-off were recalled to undergo a new dosage.

Thirty-eight patients presented 17OHP levels above the cut-off limit. In 11 (4 males, 6 females, 1 undefined gender) the diagnoses of CAH-21OHD were confirmed. Their 17OHP levels ranged from 25 to 254.5 ng/mL (mean: 133.84 ng/mL) on the first analysis and from 46.86 to 360 ng/mL (mean: 218.84 ng/mL) on the second analysis. The patients with the salt-wasting form showed higher 17OHP levels when compared to simple virilizers, both on the first analysis (mean: 169.21 ng/mL vs 27.46 ng/mL) and on the second one (mean: 227.16 ng/mL vs 110.95 ng/mL). Among the 27 infants without confirmed disease (false-positives), 17OHP levels ranged from 10.27 to 27.5 ng/mL (mean: 14.8 ng/mL) on the first sample and from 2.39 to 32.39 ng/mL (mean: 10.07 ng/mL) on the second. In this group, 8 children maintained borderline 17OHP levels during a variable period, but in 7 of them it was normalized before the first year of life. In the remaining case, who was asymptomatic after 8 years of follow-up, a cortrosin stimulation test was compatible with the non-classic form of the disease.

These data confirm that 17OHP analysis was a reliable test to CAH-21OHD neonatal screening and was able to differentiate between normal infants and those with the classical form of CAH-21OHD.