You should refer to the following table of range to interpret your test results:

aPTT Test Range	aPTT Result
Below 21 seconds	Lower than normal aPTT
Between 21 to 35 seconds	Normal aPTT
Above 35 seconds	Higher than normal aPTT

The aPTT Test results can often vary from lab to lab because of the different equipment used to conduct tests on the collected aPTT Test blood sample.

The Activated Partial Thromboplastin Clotting Time (or aPTT) can vary for some groups, which should be kept in mind while getting the aPTT Test done.

For children: The time it takes for a child’s body, especially infants in the age group of 1 to 6 months, to clot at the bleeding site is usually longer than what it takes an adult. Keeping this in mind, the reference range for normal aPTT will also be different for children and should be interpreted according to the lab’s standards.
For pregnant women: For pregnant women, the aPTT can come out to be higher than the normal aPTT range. So, a pregnant woman’s results should be interpreted differently. The lab technician or the doctor should be consulted to interpret the aPTT Test results.