Serum 17-Hydroxyprogesterone Levels in Term and Preterm Infants

Kim, Min Seong; Kim, Jeong Nyun; Park, Mi Jung; Chung, Churl Young

Abstract

PURPOSE
The incidence of congenital adrenal hyperplasia(CAH) is 1/5,000- 1/20,000 births and thus the importance of the neonatal screening test is being emphasized. However, the reference value for the term and preterm infants has not yet been established and false positive values are frequent due the immature hypothalamic-adrenal axis of the preterm infants or the stress-induced adrenal dysfunction. Therefore, we analyzed the 17-hydroxyprogesterone(17-OHP) concentration in terms of gestational age, birth weight, and postnatal state to establish the reference range for the Korean term and preterm infants.
METHODS
We analyzed the results of the CAH screening test retrospectively, which was performed on 737 neonates(624 fullterm neonates, 113 premature neonates) born between January 1998 through July 1998 in Inje University College of Medicine Sanggye Paik Hospital. Mean gestational age and birth weight of infants were 38.2+/-2.6 weeks and 3,116+/-674kg respectively. 17-OHP screening test was performed on 4.9+/-3.8days after birth by obtaining blood samples from the heelstick of neonates. 17-OHP concentration was measured by the ELISA kit(ICN Co.) and repeated the procedure if the result was higher than 35ng/ml.
RESULTS
1) 17-OHP concentration of the preterm infants was significantly higher than that of the fullterm infants(19.1+/-12.3ng/ml vs 11.7+/-7.8ng/ml, P=0.001). 17-OHP concentration was inversely proportional to gestational age. 2)17-OHP concentration was inversely proportional to birth weight(r=0.22, P>0.01). 17-OHP concentration according to birth weight was as follows.:below 1,500g was 26.7+/-11.7ng/ml, 1,500 to 2,000g was 18.0+/-13.9ng/ml, 2,001 to 2,500g was 17.9+/-10.5ng/ml, 2,501 to 3,000g was 12.1+/-7.9ng/ml, 3,001 to 3,500g was 11.5+/-8.1ng/ml, above 3,500g was 11.4+/-7.5ng/ml. There was a significant decline in the 17-OHP concentration as the birth weight increased. 3) 17-OHP concentration was gradually decreased as sampling date increased. 4) The gender of the infants did not influence the 17-OHP concentration(male 13.0+/-9.1 vs female 12.7+/-9.0). 5)17-OHP concentration were significantly higher in sick preterm infants than healthy preterm infants. 6)Six cases, whose 17-OHP concentration were greater than 35ng/ml, were all preterm and low birth weight infants. Reexamination after one week showed the value within normal range. No CAH cases were diagnosed in the study.
CONCLUSION
17-OHP concentration was inversely proportional to gestational age and birth weight. Therefore, reference ranges of 17-OHP concentration should be subdivided according to gestational age and birth weight. Further research about perinatal risk factors affecting the 17-OHP concentration will be required.