The quadruple marker tests for different conditions. The normal range or cut off values are different in each condition as follows
For Neural Tube Defects the normal range for Quadruple Marker is an Alpha Feto Protein (MoM / Median of Means) of < 2.5. Values below the normal range do not rule out neural tube defects. SImilarly values above 2.5 do not necessarily mean that a Neural Tube defect is present, but only that there is a higher risk.
For trisomy 18 and Trisomy 21(Down's Syndrome) the normal range for Quadruple Marker is 1/100 and 1/270 respectively.
Values can be significantly affected by other and an variables like age, race, smoking history, and history of amniocentesis, as well as a correct estimation of gestational age is necessary for accurate screening.