At a glance

Also known as

Total inhibin; inhibin A and inhibin B (two forms) --- NOTE: Inhibin A testing is not able to be performed in Australia at present as no reagents are available. Anti-Mullerian hormone (AMH) should be used instead as a tumour marker for granulosa cell tumours.

Why get tested?
To test for levels of inhibin, a hormone involved in reproduction in men and women. In women, it is mainly produced by the ovaries and in pregnancy, also by the placenta. In men, it is mainly produced by the testicles
 
When to get tested?
Inhibin B is used to help test how well a woman's ovaries are working and inhibin A is used in pregnancy as part of the quadruple or quad test to check the wellbeing of the developing baby. Total inhibin, inhibin A and/or inhibin B may also be used to monitor tumours of the ovary. Inhibin B is used to help assess the cause of conditions affecting the sex organs of babies (ambiguous genitalia). Less commonly, it is used as a fertility test in men
 
Sample required?
A blood sample drawn from a vein in your arm
 
Test preparation needed?
None
 

What is being tested?

Inhibin tests include separate tests for the two forms of inhibin - inhibin A and inhibin B, as well as a test that measures both forms together - total inhibin, often simply known as inhibin. Most testing is performed for women.
 
How is the sample collected for testing?
A blood sample is obtained by inserting a needle into a vein in the arm.
 
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
 

The Test

How is it used?

  • In women who are having trouble becoming pregnant the level of inhibin B may be tested to see if part of the problem is that the ovaries are not working well.
  • In women with symptoms and signs that suggest polycystic ovarian syndrome, inhibin B level can be measured as a test of how well the ovaries are working.
  • In pregnant women having tests to check the wellbeing of the baby, inhibin A is one of a group of four blood tests known as the quadruple or quad test that are used together to assess the risk of the baby having a serious abnormality.
  • In a woman being treated for a tumour of the ovary, regular testing of the inhibin level can monitor the effectiveness of treatment.
  • In men who are having difficulty becoming a father (infertility), levels of hormones such as inhibin B may be tested to see if part of the problem is that the testicles are not working well.

When is it requested?

  • Hormone levels such as inhibin B can be requested if a woman’s ovaries appear to be not be working well. This is usually because she is having trouble becoming pregnant or has symptoms and signs of polycystic ovarian syndrome.
  • In pregnant women having an inhibin A level to test for the wellbeing of the developing baby, the quadruple or quad test is performed in the second trimester of pregnancy - around the middle of pregnancy. It may also be recommended if earlier testing has been missed, if there have been problems with previous pregnancies or there is some other reason to be concerned about the growing baby.
  • In women who have a tumour of the ovary, an inhibin level may be performed at the beginning of treatment to assess whether the tumour is producing inhibin. Throughout treatment, regular testing of the inhibin level may be used to monitor the effectiveness of treatment.
  • In men being tested because they are having difficulty becoming a father (infertility), levels of hormones such as inhibin B may be tested to see how well the testicles are working. Inhibin B is used to help assess the cause of conditions affecting the sex organs of babies (ambiguous genitalia).   

What does the test result mean?

  • In women having tests to see how well their ovaries are working, a low inhibin B level may suggest that the ovaries are not working well.
  • In pregnant women having a quadruple or quad test to check the wellbeing of the developing baby, a high level of inhibin A, along with other unusual test results, suggests the possibility of the baby having a serious abnormality. Further tests will be recommended to confirm whether there is a problem and, if so, assess what that problem is.
  • In women being treated for a tumour of the ovary, the inhibin level should be low if the treatment is working well.
  • In males (baby boys or men) a low inhibin B level suggests that the testicles may not be working well.  
About Reference Intervals

Is there anything else I should know?

Inhibin tests may measure the level of all inhibin in the blood (total inhibin) or one of two different forms of inhibin - inhibin A or inhibin B. Your doctor will request the test that will be most useful for you.

If you are having regular inhibin levels to monitor your condition it is better if you have the same form of inhibin tested and if the test is performed in the same way every time. To be sure, your doctor may recommend that your blood sample is sent to the same laboratory every time.

In younger women, the inhibin level varies throughout the menstrual cycle. To understand what the test means, your doctor may need to know what stage of your cycle you are in at the time of the blood test. 
 

Common Questions

Can I have an inhibin test to tell if I have a tumour of the ovary ?

No. Like most other `tumour marker' tests, the inhibin level on its own is not a reliable test of whether you have a tumour or not. It is most useful after you have been diagnosed with a tumour of the ovary by having tissue removed and examined under a microscope.    

What other blood tests should I have?

If your doctor has recommended an inhibin test, they may recommend other blood tests be performed at the same time. For example, if you are a woman having tests to see how well your ovaries are working, other tests may be requested including the anti-Mullerian hormone (AMH) level (also known as the `egg-timer’ test) and other female hormone levels such as follicle-stimulating hormone (FSH). If you are pregnant and having the quadruple or `quad' test, your blood will be tested for four hormones - inhibin A, alpha-fetoprotein, a form of the female hormone oestrogen (unconjugated oestriol) and a form of beta HCG (free beta HCG). If you are having inhibin testing as part of your treatment of a tumour of the ovary, other `tumour marker' tests may be performed, such as CA-125.  

Last Review Date: April 24, 2016