Study of 17-alpha-hydroxy Progesterone in Preterm Infants

Choi, Yong Sung; Lee, Byong Sop; Kim, Ki Soo; Kim, Ellen Ai Rhan

Abstract

PURPOSE
In preterm infants, neonatologists often encounter abnormally high level of 17-alpha-hydroxy progesterone (17-OHP), however as there is no normative reference level for Korean preterm neonates, repeated tests for 17-OHP are conducted until the level reaches the normal value of term infants. The aim for the study is to investigate the longitudinal follow up of 17 OHP levels according to gestational age.
METHODS
The samples for 17-OHP were obtained as tandem mass spectrometry (TMS) by heel prick between the 3rd and 7th day of life from 1,040 preterm infants who were born at Asan Medical Center from June 2008 to June 2010. If initial 17-OHP level was abnormal (>12 ng/mL), the serum levels were followed every 2-4 weeks until normalization.
RESULTS
The mean levels of 17-OHP obtained from initial TMS according to gestational age were as follows: 24-26 weeks (26.4+/-20.7 ng/mL, n=20); 27-28 weeks (14.8+/-14.6 ng/mL, n=39); 29-30 weeks (7.6+/-7.3 ng/mL, n=54); 31-32 weeks (5.1+/-5.8 ng/mL, n=86); 33-34 weeks (4.6+/-3.9 ng/mL, n=186); 35 weeks (5.0+/-5.5 ng/mL, n=251); and 36 week (3.6+/-2.3 ng/mL, n=403). The mean and 99.5 percentile 17-OHP levels correlated inversely with gestational age. Those 63 infants (mean gestational age 28.6+/-4.1 weeks) whose initial 17-OHP levels were abnormally high, all became normalized at mean of 67.2+/-49.0 days. The mean number of follow-up was 2.9+/-1.9 times (range: 1-7 times) until normalization.
CONCLUSION
The 17-OHP levels correlated inversely with gestational age and the number of false-positive results in the absence of congenital adrenal hyperplasia is high among preterm population. The percentile values presented here for 17-OHP in relation to gestational age could serve as a useful guideline for 17-OHP level follow up.