Plasma Thromboplastin Clotting Time
Synonyms
Activated partial thromboplastin time (APTT)
Purpose
Plasma Thromboplastin Clotting Time test measures the amount of time it takes for a blood clot to form. Done together with prothrombin time, it helps assess clotting disorders as well as bleeding disorders.
Patient Preparation
There are no special patient preparations for this test. The patient, however, should inform the physician about medications that they are on.
Samples
2.7 ml of whole blood plasma collected in Sodium citrate tube (blue top). Sample should be gently mixed after collection for adequate mixing of the anticoagulant with blood. The sample collection tube should not be opened unless plasma will be frozen for storage. In case of intended delays in testing, the sample should be centrifuged for 10min and plasma separated and frozen immediately at 40c, until testing.
Reference Range
21-36 seconds.
Results Turnaround
Within 24 hours after sample collection.
Diseases / Diagnostic indicators
Abnormal APTT results may be an indicator of clotting factor deficiencies, which could be inherited or acquired, non-specific and specific inhibitors, anticoagulation therapies, blood thinners, leukemia, and pregnancy.
Underlying conditions that may cause clotting factor deficiencies include vitamin K deficiency and liver disease. Inherited clotting factor deficiencies include: Haemophilia A, Haemophilia B, Von Willebrand disease, factor XII, factor XI,