This study was undertaken to identify factors that influence 17-OHP levels in preterm infants and to suggest a reasonable follow-up schedule of screening for congenital adrenal hyperplasia (CAH) in preterm infants.

The 17-OHP concentrations in filter paper blood spots of 427 preterm infants were obtained. The effects of gestational age (GA), systemic diseases, and antenatal dexamethasone on screening and follow-up 17-OHP values were investigated.

The screening 17-OHP values were markedly variable (range: 0.1-143.3 ng/mL). The screening 17-OHP levels were negatively correlated with GA (r=-0.535, P <0.01). In infants with GA <32 weeks, the screening 17-OHP levels were significantly higher in sick infants or infant with hypotension than in healthy infants. The screening values of prenatal dexamethasone-treated infants had a tendency to be low. In infants with initial 17-OHP values ≥20 ng/mL, the intervals until rescreening 17-OHP <10 ng/mL or serum 17-OHP <20 ng/mL were negatively correlated with GA (r=-0.541, P <0.01) and were prolonged in infants with bronchopulmonary dysplasia ( P <0.01). None of the preterm infants were confirmatively diagnosed with CAH.

The 17-OHP values of preterm infants were influenced by GA, prenatal dexamethasone, and postnatal diseases. Because the 17-OHP vlues of preterm infants were markedly variable, a follow-up schedule should be developed considering both 17-OHP values and clinical status.