Tissue thromboplastin or Tissue factor
(factor III)

Other names of this test:

• CD14 Coagulation blood test

• Tissue Factor (TF)

• Tissue Thromboplastin

is the primary initiator of the extrinsic coagulation pathway. It is a transmembrane protein that is constitutively expressed in subendothelial cells throughout the vasculature and is inducible on endothelial cells and monocytes. Damage to the vessel wall exposes Coagulation Factor III to circulating Factor VII, triggering the proteolytic cascade that results in fibrin clot formation. Coagulation Factor III plays an important role in thrombotic diseases, disseminated intravascular coagulation, and atherosclerosis. It also plays a role in non-hemostatic inflammation, angiogenesis, and tumor progression.

Sample type:

Specimen Plasma Na citrate (light blue top tube)

Uses:

• To measure the concentration of clotting factor in the blood.

• To find inherited or acquired bleeding disorders.

• If there is a history of bruises or excessive bleeding.

• If there are prolonged PT or PTT.

• acquired cases such as vitamin K deficiency or liver disease.

• may be advised monitor the treatment of a patient with factor deficiency

Precautions:

No special preparation is needed prior to the test

• The plasma is needed, take 5 ml of venous blood and add sodium citrate as the anticoagulant.

• Perform the assay immediately or as soon as possible.

• Freeze if it is delayed >2 hours

Interfering factors:

Tissue factor (TF) is best known as the primary cellular initiator of blood coagulation. After vessel injury, the TF: FVIIa complex activates the coagulation protease cascade, which leads to fibrin deposition and activation of platelets.

Pre analytical errors:

• Hemolysis

• Under-filled blood collection tubes

• Clotted blood samples/improper mixing

• Sample collected from wrong patient

• Samples labeled incorrectly

Corrective action:

Tissue factor (TF) expression by nonvascular cells plays an essential role in hemostasis by activating blood coagulation. In contrast, TF expression by vascular cells induces intravascular thrombosis. TF-dependent assembly of coagulation proteases on vascular cells activates protease activated receptors, which contributes to inflammation, angiogenesis, and metastasis.

Post analytical action:

• Transcription errors in reporting

• Report sent to the wrong location

• Report illegible

• Report not sent

Reference Range:

75 – 145 %