Dimeric inhibin A (DIA)

Would you like to know what lab results mean? Medical Tests Analyzer Software will explain and clarify your lab test report.

Dimeric inhibin A (DIA) is a glycoprotein hormone synthesized by the corpus luteum and placenta in pregnancy. The specific role of DIA during pregnancy has not been determined. Maternal serum DIA levels increase during the first trimester, then decline after 10 weeks and remain stable between 15-25 weeks. DIA levels rise again after 25 weeks to reach a peak at term.
Quantification of inhibin A is part of the prenatal quad screen that can be administered during pregnancy at a gestational age of 16-18 weeks. An elevated inhibin A (along with an increased beta-hCG, decreased AFP, and a decreased estriol) is suggestive of the presence of a fetus with Down syndrome. As a screening test, abnormal quad screen test results need to be followed up with more definitive tests.
It also has been used as a marker for ovarian cancer.

Test results
An increased level of inhibin-A is associated with an increased risk for trisomy 21 (Down Syndrome). A high inhibin-A may be associated with a risk for preterm delivery. High serum inhibin A levels in the first trimester of pregnancy could be used as an early risk marker for preeclampsia.

The inhibin A concentrations were significantly lower in cases where pregnancies occurred in women without functioning ovaries (HRT protocol) reflecting the absence of a functional corpus luteum, and in women where the endometrium was prepared by NAT protocol (single corpus luteum), compared with those women who received the ovarian stimulation protocol (multiple corpora lutea).

Also you should know
It is important to remember that the inhibin A test (as a part of quad screen) is a screening test and not a diagnostic test. This test only notes that a mother is at risk of carrying a baby with a genetic disease. Many women who experience an abnormal test result go on to deliver healthy babies.

Abnormal test results warrant additional testing in order to make a diagnosis. A more conservative approach involves performing a second quad screen followed by a high definition ultrasound. If the testing still maintains abnormal results, a more invasive procedure such as amniocentesis may be performed.

Any invasive procedure should be discussed thoroughly with your healthcare provider and between you and your partner. Additional counseling and discussions with a counselor, social worker or minister may prove helpful.
All information on this page is intended for your general knowledge only and does not provide medical advice, diagnosis or treatment.