A longer-than-normal PTT or APTT can mean a lack of or low level of one of the blood clotting factors or another substance needed to clot blood. This can be caused by bleeding disorders, such as hemophilia or von Willebrand's disease.
What does a low PTT mean?
Low levels of clotting factors can prevent a clot from forming. A deficiency in clotting factors can lead to symptoms such as excessive bleeding, persistent nosebleeds, and easy bruising.
What happens if aPTT is low?
Critical values that should prompt a clinical alert are as follows: aPTT: More than 70 seconds (signifies spontaneous bleeding) PTT: More than 100 seconds (signifies spontaneous bleeding)