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Hormone Inhibin A


There is very little chance of a problem from having a blood sample taken from a vein.

  • You may get a small bruise at the site. You can lower the chance of bruising by keeping pressure on the site for several minutes.
  • In rare cases, the vein may become swollen after the blood sample is taken. This problem is called phlebitis. A warm compress can be used several times a day to treat this.
  • Ongoing bleeding can be a problem for people with bleeding disorders. Aspirin, warfarin (Coumadin), and other blood-thinning medicines can make bleeding more likely. If you have bleeding or clotting problems, or if you take blood-thinning medicine, tell your doctor before your blood sample is taken.


The inhibin A test is done to measure the amount of this hormone in a pregnant woman's blood to see if there is an increased chance the baby may have Down syndrome. Inhibin A is made by the placenta during pregnancy.

A normal result means the level of the hormone inhibin A is low, or negative. An abnormal result means the level of the hormone inhibin A is high, or positive.1 The level of the hormone must be reviewed with the quad screen blood tests.

All abnormal results will need to be discussed with your doctor.

What Affects the Test

Things that may affect your test results include:

  • If you smoke. This may increase the level of inhibin A in the blood.
  • If you are obese. This may decrease the level of inhibin A in the blood.

The results of the quad screen, including inhibin A, take into account a woman's age, race, weight, and whether she has diabetes.

What To Think About

  • The maternal quad screen looks for possible problems in your developing baby (fetus). You can have an ultrasound if your quad screen is abnormal. If an ultrasound cannot find the cause of the abnormal results, an amniocentesis may be recommended.
  • If abnormal levels of inhibin A are found, talk with your doctor or a genetic counselor. The test results can be abnormal, even when nothing is wrong.
  • The level of inhibin A in the blood is often used in a maternal serum quadruple screening test. To learn more, see the topic Triple or Quad Screening for Birth Defects.

WebMD Medical Reference from Healthwise

Last Updated: April 04, 2012
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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