Thromboplastin Information and Courses from MediaLab, Inc.
These are the MediaLab courses that cover Thromboplastin and links to relevant pages within the course.
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| When performing a routine venipuncture in which you are collecting a serum separator tube for immunology, a green top tube for chemistry, a blue top tube for coagulation, and a lavender top tube for hematology, which tube should be collected first? | View Page |
| Secondary Hemostasis – The Intrinsic Pathway Then, activated factor IX (IXa), along with ionized calcium, platelet factor, and factor VIII, activate factor X, which is a direct precursor of thrombin in the common pathway. The activation of factor X signals the beginning of the common pathway. The activated partial thromboplastin time (APTT) is used to monitor the intrinsic pathway and the effectiveness of heparin therapy. | View Page |
| Laboratory Tests of Hemostatic Function - APTT The activated partial thromboplastin time (APTT) is a screening test that helps to assess the functionality of both the intrinsic and common pathways. The effectiveness and presence of all the coagulation factors are assayed by this diagnostic test with the exception of factors VII and XIII. The results of the activated partial thromboplastin time are used in conjunction with other diagnostic tests, as well as the clinical picture of the patient, to determine hemostatic abnormalities which may be present. In addition to being an integral part of the coagulation disorder assessment process, the APTT is used to determine therapeutic effectiveness of heparin administration. Activated partial thromboplastin time results are presented to the clinician in seconds- the actual time elapsed until a clot was detected using the laboratory's instrument/reagent system. | View Page |
| Anticoagulation Therapy - Heparin Therapy The use of heparin is prophylactic. It is used either to prevent thromboembolism (a condition in which a blood clot forms inside a vessel), or used to limit a previous thromboembolism. Heparin inhibits thrombin. The degree of inhibition is dosage dependant. Low doses of heparin inhibit initial thrombin formation in the coagulation cascade, and act to slow down overall thrombin generation. At higher doses, heparin can inhibit thrombin entirely, making blood coagulation impossible. Heparin is a potent anticoagulant. Accurate monitoring is essential. The activated partial thromboplastin time (APTT) and/or activated clotting time is used to monitor unfractionated heparin therapy. | View Page |
| Blood Collection Tubes Most blood collection tubes contain an additive that either accelerates clotting of the blood (clot activator) or prevents the blood from clotting (anticoagulant). A tube that contains a clot activator will produce a serum sample when the blood is separated by centrifugation and a tube that contains an anticoagulant will produce a plasma sample after centrifugation. Some tests require the use of serum, some require plasma, and other tests require anticoagulated whole blood. The table below lists the most commonly used blood collection tubes. Tube cap color Additive Function of Additive Common laboratory tests Light-blue 3.2% Sodium citrate Prevents blood from clotting by binding calcium Coagulation Red or gold (mottled or "tiger" top used with some tubes is not shown) Serum tube with or without clot activator or gel Clot activator promotes blood clotting with glass or silica particles. Gel separates serum from cells. Chemistry, serology, immunology Green Sodium or lithium heparin with or without gel Prevents clotting by inhibiting thrombin and thromboplastin Stat and routine chemistry Lavender or pink Potassium EDTA Prevents clotting by binding calcium Hematology and blood bank Gray Sodium fluoride, and sodium or potassium oxalate Fluoride inhibits glycolysis, and oxalate prevents clotting by precipitating calcium. Glucose (especially when testing will be delayed), blood alcohol, lactic acid | View Page |