Can beta hcg at 16-21 weeks be used as one of the prenatal laboratory to predict
preeclampsia?
Human chronic gonadotropin (hcg) refers to the glycoprotein hormone that results
during pregnancy and made by the developing embryo following conception.[1]
Beta hcg or the pregnancy hormone is produced by the implanting egg’s cells and can
also occur without an embryo. It can be detected 8 to 9 days after ovulation in maternal
plasma or urine and reaches its peak at about 8 to 10 weeks and then declines in the
course of the pregnancy.[2]
Preeclampsia refers to the incidence of hypertension in pregnancy linked with significant
amounts of protein in the urine and entails damage to the maternal endothelium,
kidneys and liver. It may progress from 20 weeks gestation and differs among patients,
with most cases being diagnosed as pre-term. Preeclampsia has no known cure
excepting Caesarean section or induction of labor.[3]
According to one study, women prone to hypertension development during pregnancy
may be identified by a second-trimester test for elevated levels of beta-human chronic
gonadotropin (beta-hcg), which however, may lack the accuracy in identifying women at
risk for preeclampsia. Based on a study of preeclampsia in 6,286 nondiabetic women,
those who had more than one child and had elevated beta-hcg levels had a greater risk
of developing hypertension and preeclampsia.[4]
According to a second study, second-trimester elevated maternal urine beta-core
fragment of hcg predicted small for gestational age (SGA) infants, and was better in
prediction than other serum analytes. The beta-core fragment that accumulates in
maternal urine is the terminal metabolite of hcg. There was previous evidence that
beta-core fragment of hcg may be used as trophoblastic function marker, with second-
trimester urine beta-core fragment having been elevated in clinically normal women who
became preeclamptic in due time.[5]
Spot urine specimens from women in the gestational age range of 14-24 weeks were
obtained and refrigerated. To determine whether there was significant connection
between beta-core fragment levels and later SGA birth, the Mantel-Haenszel test of
linear association was used. There was a plotting of receiver operating characteristics
(ROC) sensitivity curve against false-positive rate for SGA prediction at various beta-
core fragment threshold values.[6]
The etiology of fetal growth restriction (FGR) is heterogeneous, with many factors being
considered, and preeclampsia is an accepted FGR risk factor. Women may be
predisposed to preeclampsia if there is failure of the second wave of endovascular
trophoblastic invasion. Based on the findings, early disturbance of trophoblast
dysfunction occurs in a notable percentage of women who deliver SGA offspring. The
intial effect of a hypersecretory state development might be the cause of heightened
levels of placental function markers found in preeclamptic women, like hcg, inhibin-A
and activin-A. As FGR predictor, beta-core fragment may be better than its parent
molecule.[7]
According to a third study, there is strong correlation between elevated maternal
inhibin A concentration with a later risk of preeclampsia. Further investigation is in
order on the potential use of second trimester inhibin A measurement in a preeclampsia
screening strategy.[8]
[1] “Human chronic gonadotropin”, Wikipedia, 27 April 2011,
<http://en.wikipedia.org/wiki/Human_chorionic_gonadotropin> [accessed 30 April 2011]
[2] “What is beta hcg?”, OBfocus, 2009, <http://www.obfocus.com/questions/qanda7.htm>
[accessed 30 April 2011]
[3] “Pre-eclampsia”, Wikipedia, 2 April 2011, <http://en.wikipedia.org/wiki/Pre-eclampsia>
[accessed 30 April 2011]
[4] Ellice S. Lieberman et al, “The value of elevated second-trimester beta-human chronic gonadotropin in
predicting development of preeclampsia”, Abstracts Health, 1997,
<http://www.faqs.org/abstracts/Health/The-value-of-elevated-second-trimester-beta-human-chorionic-gonadotropin-in-predicting-development-o.html> [accessed 30 April 2011]
[5] Ray Bahado-Singh, MD et al, “Maternal Urine [beta]-core hcg Fragment Level and Small for Gestational
Age Neonates”, Obstetrics & Gynecology, May 2000,
<http://journals.lww.com/greenjournal/Fulltext/2000/05000/Maternal_Urine__beta__core_hCG_Fragment_Level_> [accessed 30 April 2011]
[6] ibid
[7] ibid
[8] J. Aquilina et al, “Second-Trimester Maternal Serum Inhibin A Concentration as an Early Marker for
Preeclampsia”, PubMed.gov, July 1999, <http://www.ncbi.nlm.nih.gov/pubmed/10411808>
[accessed 30 April 2011]
Credit:ivythesis.typepad.com
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