J Lab Med Qual Assur.  2010 Dec;32(2):211-216.

Establishment of the Separate Cutoff Values of 17-alpha-hydroxyprogesterone in Neonatal Screening Program for Congenital Adrenal Hyperplasia according to Birth Weight

• Song SM
• Lee HJ
• Yoon HR
• Lee KR

Abstract

BACKGROUND
In Korea, 17-alpha-hydroxyprogesterone (17-OHP) neonatal screening for congenital adrenal hyperplasia (CAH) has a high false positive rate. Preterm infants have higher levels of 17-OHP than term infants. We established the separate cutoff values of 17-OHP under the guideline of the Clinical and Laboratory Standard Institute C28-A3 to reduce a false positive rate.
METHODS
The 17-OHP enzyme-immunoassay was used in blood spots of 22,601 newborns. To decide whether to partition cutoff values based on sex, sampling date and birth weight was assessed by Z-test and standard deviation (SD) ratio. If the result was significant, we estimated the cutoff value with 90% confidence intervals (CIs) using the nonparametric method.
RESULTS
In the subclasses based on sex and sampling date, the results were not significant. However, the birth weight-adjusted subclasses (SD ratio > 1.5) showed that it was necessary to distinguish low-birth-weight infants from the others. We selected the subclass categories to reflect the concept of low- or very-low-birth-weight infant. The maximum percentile to define a 90% CI was chosen in each subclass. After applied the re-estimated cutoff value, the recall rate was decreased from 0.6% to less than 0.2%.
CONCLUSIONS
The birth weight-adjusted cutoff value of 17-OHP in neonatal screening for CAH can be reduced the false positive rate of low-birth-weight infants. This approach would decrease unnecessary blood draws, medical evaluation, parental anxiety and burden on health care resources.

Keyword

Neonatal screening; 17-alpha-hydroxyprogesterone; Congenital adrenal hyperplasia; Low-birth-weight infants

MeSH Terms

17-alpha-Hydroxyprogesterone
Adrenal Hyperplasia, Congenital
Anxiety
Birth Weight
Delivery of Health Care
Humans
Infant
Infant, Low Birth Weight
Infant, Newborn
Infant, Premature
Infant, Very Low Birth Weight
Korea
Neonatal Screening
Parents
Parturition
17-alpha-Hydroxyprogesterone