Objective
Definition of upper limits for 17α-hydroxyprogesterone (17α-OHP) is important as its measurement is used in screening for congenital adrenal hyperplasia. This study aimed at investigating the cut off concentrations in relation to the day of sample collection.
Methods
17α-OHP concentration was determined in dried filter paper blood spots taken from cord blood and by heel pricking up to the sixth day of life. A sensitive fluoroimmunoassay (DELFIA) method was used. Samples from 1091 apparently healthy full term neonates were tested. Samples were separated according to the age of sampling.
Results
The 17α-OHP (nmol/l blood) (median and 97.5th centile) concentrations according to the age of sampling were: cord blood (n=126) 123.7, 265.6; first day 0–6 hours (n=30) 49.4, 80.3; 6–12 hours (n=57) 42.7, 79.8; 12–18 hours (n=58) 38.1, 62.7; 18–24 hours (n=67) 28.8, 49.7; second day 24–36 hours (n=51) 23.6, 43.3; 36–48 hours (n=63) 19.9, 35.4; third day (n=200) 10.6, 23.5; fourth day (n=197) 8.8, 20.8; fifth day (n=76) 6.4, 18.3; sixth day (n=166) 6.6, 19.4.
Conclusion
Cord 17α-OHP concentrations were very high as previously described, probably owing to steroid production by fetal adrenal glands. Therefore, cord blood is not useful for screening purposes. Thereafter there is a gradual decline in 17α-OHP median concentrations. A cut off value of 30 nmol/l blood was useful in samples obtained after 48 hours of life. However, cut off values before 48 hours should be adjusted according to the sampling time.
