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Normal results vary based on the method and activators used. Normal APTT results are usually between 25-40 seconds; PTT results are between 60-70 seconds.APTT results for a patient on heparin should be 1.5-2.5 times normal values.An APTT longer than 100 seconds indicates spontaneous bleeding.artial thromboplastin time (PTT), a test for detecting coagulation defects of the intrinsic system by adding activated partial thromboplastin to a sample of test plasma and to a control sample of normal plasma. The time required for the formation of a clot in test plasma is compared with that in the normal plasma.
Abnormal values. 1  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. 2  This can be caused by bleeding disorders, such as hemophilia or von Willebrand's disease.artial thromboplastin time (PTT) is a blood test that measures the time it takes your blood to clot. The normal values listed here-called a reference range-are just a guide.