🧪 What is Inhibin-A?

Inhibin-A is a glycoprotein hormone primarily secreted by the placenta during pregnancy and by granulosa cells in the ovaries and Sertoli cells in the testes.

• It plays a role in regulating follicle-stimulating hormone (FSH).
• In pregnancy, it's measured as part of maternal serum screening for fetal chromosomal abnormalities like Down syndrome (trisomy 21).
• Also used as a tumor marker in some ovarian and testicular cancers.

❓ Why is the Inhibin-A Test Done?

🟣 In Pregnancy

• Part of the Quadruple Test (along with AFP, hCG, and unconjugated estriol) done in the second trimester (15–20 weeks)
• Helps assess risk of:
  • Trisomy 21 (Down syndrome)
  • Trisomy 18
  • Neural tube defects (indirectly)

🟣 In Oncology / Gynecology

• Tumor marker for granulosa cell tumors of the ovary
• Monitors recurrence or progression of sex cord-stromal tumors
• May be used in testicular cancer workup

📊 Normal Ranges

🟣 In Pregnancy (Second Trimester)

• Reported as Multiples of Median (MoM) for gestational age
  • Normal Inhibin-A ≈ 0.5–2.0 MoM
  • Elevated (>2.0 MoM): Increased risk of Down syndrome

🟣 Non-pregnant Women / Men

• Typically very low or undetectable

Note: Reference values vary with lab, age, gender, and pregnancy status.

📈 Interpretation of Results

🧠 Associated Organs & Conditions

🔄 Related / Follow-Up Tests

• Quad Marker Test – AFP, hCG, Estriol, Inhibin-A (combined risk score)
• Ultrasound (NT scan or anomaly scan)
• Amniocentesis / NIPT – For definitive genetic diagnosis
• Tumor markers – CA-125, AFP, hCG (if cancer suspected)
• FSH, LH, Estradiol – For hormonal evaluation

✅ Fasting Required?

📝 Summary Table