RESUMEN
UNLABELLED: Determination of 17α-nyaroxyprogesterone (17OHP) is used for the diagnosis and monitoring of Congenital Adrenal Hyperplasia (CAH). Problems associated with the specificity of antibodies used in direct immunoassays can yield high false results. OBJECTIVES: To analyze serum levels of direct 17OHP (17OHPd) and previous extraction (17OHPe) in the neonatal period, in order to establish reference values. To relate levels of 17OHPd and 17OHPe with other androgens in CAH patients. SUBJECTS AND METHODS: Serum 17OHPd and 17OHPe were measured via RIA-DPC in 400 healthy newborns and infants (aged 2-365 days), and 100 treated CAH patients (aged 1-18 years). The extraction was performed with 3% isopropanol/heptane. The influence of age and gender was assessed by ANOVA. RESULTS: The serum levels of 17OHP were significantly correlated with chronological age, but not with gestational age, sex or birth weight. The difference between 17OHPd and 17OHPe decreased with age. The correlation index between 17OHPd and 17OHPe in CAH patients was 0.93 (p < 0.01). CONCLUSION: The present results provide 17OHP reference values for infants from birth up to one year of life. The extraction method is necessary in the neonatal period up to 6 months of life. Our data might be useful to make an early CAH diagnosis and follow-up newborns with high 17OHP levels without adrenal pathology.