CPT® Code 85260

The CPT® Code 85260 refers to a laboratory test specifically designed to measure the activity of clotting factor X, also known as Stuart-Prower factor. This factor is a crucial component in the coagulation cascade, which is the series of events that lead to blood clot formation. Factor X is classified as a vitamin K dependent serine protease, meaning that its activity is reliant on the presence of vitamin K, which is essential for the synthesis of several clotting factors in the liver. The activation of factor X is a pivotal step in the clotting process, as it leads to the conversion of prothrombin to thrombin, ultimately resulting in the formation of a fibrin clot. A deficiency in factor X is considered rare and can arise from various causes, including inherited genetic disorders, vitamin K deficiency, systemic amyloidosis, severe liver disease, or the effects of anticoagulant therapy. Clinically, individuals with factor X deficiency may present with symptoms such as easy bruising, frequent nosebleeds, hematuria (blood in urine), heavy menstrual bleeding, and bleeding into soft tissues or joints. The test for factor X activity is often ordered to diagnose either congenital or acquired factor X deficiency, to investigate the underlying causes of abnormal bleeding time tests such as prothrombin time (PT) and activated partial thromboplastin time (PTT), or to evaluate the impact of liver disease on the body's hemostatic mechanisms. The test is performed by obtaining a blood sample through venipuncture, which is reported separately, and the analysis is conducted on platelet-poor plasma using a prothrombin clot-based assay to accurately measure the activity of factor X.