Which of the following is not a component of triple test screening in Down syndrome?

The triple test is a second trimester screening test used to identify those pregnant women who should be offered a diagnostic test to identify whether their fetus has an aneuploidy (down syndrome) The triple screen test measures serum level of AFP, Estriol and beta-HCG. High level of hCG and low level of AFP and Estriol are suggestive of positive triple test. Down's Syndrome AFP hCG ESTRIOL || || || Quad test: triple test + inhibin alpha.