The Free Beta hCG (β-hCG) Test measures the unbound (free) beta subunit of human chorionic gonadotropin (hCG) in the blood. It is commonly used in prenatal screening for chromosomal abnormalities and pregnancy monitoring.
🔹 hCG is a hormone produced by the placenta during pregnancy.
🔹 It consists of two subunits: Alpha (α) and Beta (β).
🔹 The β subunit is unique to hCG, and the free beta hCG refers to the unbound portion circulating in the blood.
🔹 It is primarily used in first-trimester screening for chromosomal conditions like Down syndrome (Trisomy 21) and Edwards syndrome (Trisomy 18).
✅ First-Trimester Prenatal Screening (11–14 Weeks)
Part of the “Dual Marker Test” (along with PAPP-A)
Assesses risk for Down syndrome (Trisomy 21) and Edwards syndrome (Trisomy 18)
✅ Pregnancy Confirmation & Monitoring
Helps detect early pregnancy complications
✅ Tumor Marker for Certain Cancers
Detects gestational trophoblastic disease (GTD), testicular cancer, and ovarian cancer
| Gestational Age | Free Beta hCG (ng/mL) |
|---|---|
| Non-Pregnant Women | < 1 ng/mL |
| 5 – 6 Weeks | 10 – 50 ng/mL |
| 6 – 7 Weeks | 25 – 100 ng/mL |
| 7 – 8 Weeks | 10 – 50 ng/mL |
| 8 – 10 Weeks | 5 – 20 ng/mL |
🔹 Levels peak around 8–10 weeks and then gradually decline.
| Condition | Free Beta hCG Levels |
|---|---|
| Down Syndrome (Trisomy 21) | High (>2.5 MoM) |
| Edwards Syndrome (Trisomy 18) | Low (<0.5 MoM) |
| Normal Pregnancy | 1.0 MoM (Multiple of Median) |
🔹 Increased Free β-hCG → Higher risk of Down syndrome (Trisomy 21)
🔹 Decreased Free β-hCG → Higher risk of Edwards syndrome (Trisomy 18)
📌 MoM (Multiple of Median) = Standardized value for risk assessment
Free β-hCG is elevated in certain cancers, including:
✔ Gestational Trophoblastic Disease (GTD) (Molar Pregnancy, Choriocarcinoma)
✔ Testicular Cancer (Seminoma, Non-Seminoma)
✔ Ovarian Cancer
✔ Certain Lung & Gastrointestinal Cancers
📌 Sample: Blood (serum)
📌 Fasting: Not required
📌 Timing: Typically done between 11–14 weeks for prenatal screening
🔹 For Abnormal Prenatal Screening:
Additional tests like NIPT (Non-Invasive Prenatal Testing), Amniocentesis, or Chorionic Villus Sampling (CVS) may be recommended.
🔹 For Cancer or Molar Pregnancy:
Ultrasound, MRI, or CT scans for further evaluation
Surgical removal of tumors or abnormal tissue
Chemotherapy for advanced cases
✅ Free Beta hCG is used in first-trimester screening for Down syndrome.
✅ High levels indicate increased risk of Trisomy 21, while low levels suggest Trisomy 18.
✅ It is also a tumor marker for gestational trophoblastic disease and testicular cancer.
✅ Abnormal results may require further testing for confirmation.