Triple Marker Test
Triple Marker Test
- This test is done on pregnant woman to diagnose specific types of genetic disorders in the fetus.
- The test requires no preparation
- The test provides 3 values – AFP, Estriol and hCG
What is a Triple Marker Test ?
There are some diseases which are passed from the parents to the children which are called genetic diseases. The genes of the parents are passed in the form of chromosomes. Triple marker test is done to diagnose some specific kinds of chromosomal or genetic defects in the unborn baby. In this test the serum levels of three hormones in the blood of pregnant woman are tested.
The three hormones are :
- Alpha-fetoprotein (AFP)
- Unconjugated estriol
- Human chorionic gonadotropin (beta-hCG)
Reported Parameters
- Alpha-fetoprotein (AFP)
- Unconjugated estriol
- Human chorionic gonadotropin (beta-hCG)
All The Questions that you might have
- When and for whom is the triple marker test done ?
- Which Genetic Disorders are diagnosed through this test ?
- How to interpret the results of Triple Marker Test ?
This blood test is done on pregnant woman between 15 to 20 weeks of pregnancy. This test is mostly done in conjunction with Level 2 or Level 3 Ultrasound which also tries to find congenital anomalies in the unborn baby.
While Level 2 Ultrasound is done for every pregnant woman, Triple Marker Test is done if the expectant mother has any of the following :
- A family history of genetic problems
- Age of 35 years or more
- Diabetic and takes insulin
- Suffering or experienced prenatal viral infection
- Exposure to radiation
- Consuming medication with significant side effects
The levels of 3 hormones are checked in Triple Marker Test. The significance of each of these hormones is as follows :
Alpha-fetoprotein (AFP)
This is a protein produced by the fetus. If the levels of this hormone are high then neural tube defects like spina bifida or anencephaly are suspected.
However, the most common reason for elevated AFP levels is inaccurate dating of the pregnancy. Low levels of AFP and abnormal levels of hCG and estriol may indicate that the developing baby has Trisomy 21 (Down Syndrome), Trisomy 18 (Edwards Syndrome) or another type of chromosome abnormality.
2. Estriol
Found in both the foetus and the placenta, low levels of estriol indicate the risk of the baby being born with Down syndrome. When coupled with low AFP levels and high hCG levels, the risk is even higher.
3. Human chorionic gonadotropin (hCG)
Produced in the placenta, low levels of hCG may indicate ectopic pregnancies or even miscarriages. On the contrary, high levels of hCG may denote molar pregnancies or multiple pregnancies.
It is important to remember the triple test is a screening test and not a diagnostic test. This test only notes that a mother is at possible risk of carrying a baby with a genetic disorder. The triple screen test is known to have a high percentage of false-positive results.
Abnormal test results warrant additional testing for making a diagnosis.
Doctors frequently consider several other factors that might affect the test results including:
- The mother’s weight, ethnicity, and age
- Whether or not the mother is diabetic
- Whether or not the mother is carrying multiple fetuses
The results of Triple Marker Test need to be corroborated with the results of Level 2 or Level 3 Ultrasound with detailed study of the fetal organs. Sometimes an invasive test called amniocentesis also need to carried out before taking the decision on aborting or continuing with the pregnancy.
