Related Experiment Videos
Low levels of amniotic fluid placental alkaline phosphatase in Down's syndrome
T E Ind1, R K Iles, N C Wathen
1Department of Obstetrics, Gynaecology, St. Bartholomew's Hospital, London, UK.
Objective:
To investigate amniotic fluid placental alkaline phosphatase (PLAP) levels in normal and trisomy 21 pregnancies.
Design:
Cross sectional study.
Setting:
A tertiary referral prenatal diagnostic service.
Subjects:
Three hundred and eleven women with singleton pregnancies of normal karyotype between 10 and 23 weeks gestation and 31 women with pregnancies associated with trisomy 21 Down's syndrome.
Outcome Measures:
PLAP levels were measured by immunoradiometric assay in amniotic fluid obtained by amniocentesis.
Results:
Amniotic fluid PLAP was detectable from 12 weeks gestation and the median value rose to a peak of 4.57 iu/l at 18 weeks. Pregnancies associated with Down's syndrome had significantly lower levels with a median multiple of median (MoM) of 0.638, (U = 3374, P = 0.0016, 95% CI = 0.50, 0.89). For the 20 women with trisomy 21 pregnancies detected at 16 to 18 weeks, the median MoM was 0.482, (U = 3694, P = 0.0011, 95% CI = 0.37, 0.85).
Conclusion:
These data demonstrates that PLAP levels are reduced in the amniotic fluid of women carrying a fetus with trisomy 21.