Which factors can influence Prothrombin time (PT) test results?

Prothrombin time (PT) is a test that measures the time it takes for blood to clot, which is particularly useful in evaluating the extrinsic and common pathways of coagulation. Factors that can significantly influence PT results include liver function and nutritional status, both of which are affected by liver disease and vitamin K deficiency.

Liver disease impacts PT because the liver is responsible for synthesizing several clotting factors necessary for coagulation, including prothrombin (factor II), factors VII, IX, and X. When liver function is compromised, the production of these factors diminishes, leading to prolonged PT values.

Vitamin K deficiency also affects PT because vitamin K is crucial for the synthesis of clotting factors II, VII, IX, and X in their active forms. A deficiency in vitamin K can occur due to inadequate dietary intake, malabsorption, or certain medications. As a result, this deficiency leads to an increased PT, reflecting impaired clotting capabilities.

The other factors mentioned in the other choices do not have a direct influence on PT. While platelet count and fibrinogen levels are important in the context of overall hemostasis and clot formation, they primarily affect different tests such as the activated partial thromboplastin time (a