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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.
Reference values for aPTT vary among laboratories, but generally range between 25 and 38 seconds. The aPTT of a newborn will usually be prolonged and may be up to 55 seconds at birth.It decreases to the adult range by 6 months of age. (Note: each lab has its own reference values based upon the equipment and reagents used.). The aPTT is the most commonly used test to monitor heparin therapy.The therapeutic goal for a patient being anticoagulated with heparin, is an aPTT approximately 1.5 to 2.5 times the mean normal value.Note: each lab has its own reference values based upon the equipment and reagents used.). The aPTT is the most commonly used test to monitor heparin therapy. The therapeutic goal for a patient being anticoagulated with heparin, is an aPTT approximately 1.5 to 2.5 times the mean normal value.