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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.
To test your bodyâs blood clotting abilities, your doctor will collect a sample of your blood in a vial and add chemicals. The test measures how many seconds it takes for your blood to clot after the addition of the chemicals. This test is sometimes known as an activated partial thromboplastin time (APTT) test. Your doctor may order a PTT test to investigate the cause of prolonged or excessive bleeding. Symptoms that may prompt your doctor to order this test include: 1  frequent or heavy nosebleeds.  heavy or prolonged menstrual periods.