Pregnancy-Associated Plasma Protein A (PAPP-A) & Beta Human Chorionic Gonadotropin (Beta-hCG)

Function

Pregnancy-Associated Plasma Protein A (PAPP-A) and Beta Human Chorionic Gonadotropin (beta-hCG) are biochemical markers used primarily in the first-trimester screening (FTS) between the 11th and 14th weeks of gestation. PAPP-A is a protein produced by the placenta that plays a vital role in bone development and insulin-like growth factor (IGF) signaling. Beta-hCG is a hormone produced by the syncytiotrophoblast of the placenta, essential for maintaining the corpus luteum and progesterone production during early pregnancy.

Why it is Ordered

This panel is a non-invasive screening tool used to assess the statistical probability of chromosomal abnormalities in the fetus. When combined with a nuchal translucency (NT) ultrasound scan, it provides a detection rate of approximately 85-90% for certain trisomies. It is routinely offered to pregnant individuals to determine if further invasive diagnostic testing, like chorionic villus sampling (CVS) or amniocentesis, is warranted.

Associated Conditions

• Trisomy 21 (Down Syndrome): Typically characterized by low PAPP-A levels and high free beta-hCG levels.
• Trisomy 18 (Edwards Syndrome) & Trisomy 13 (Patau Syndrome): Generally associated with low levels of both PAPP-A and beta-hCG.
• Placental Insufficiency: Isolated low PAPP-A (below 0.4 MoM) in the first trimester is linked to increased risks of preeclampsia, fetal growth restriction (IUGR), and preterm birth later in pregnancy.
• Ectopic Pregnancy: Sub-optimal rises in hCG can indicate a non-viable or extrauterine pregnancy.