CPT® Code 85302

Protein C is a vital natural anticoagulant that plays a crucial role in the regulation of blood coagulation. Deficiencies in protein C can lead to serious health issues, including recurrent thrombosis and warfarin-induced skin necrosis, conditions that increase the risk of abnormal blood clot formation. The CPT® Code 85302 specifically refers to the measurement of protein C antigen levels in the blood, which helps in assessing the presence of this important coagulation factor. The procedure involves taking a blood sample from the patient, which is then treated with sodium citrate or citric acid to prevent clotting. This sample is subsequently incubated in microwells that are coated with antibodies specific to human protein C. During this incubation, the protein C present in the patient's sample binds to the antibodies on the well surface. Following this binding phase, a detection antibody that is conjugated with horseradish peroxidase (HRP) is introduced. After a washing step to eliminate any unbound detection antibodies, a chromogenic substrate is added, leading to the formation of a soluble colored product. The intensity of this color change is then measured, providing a quantitative assessment of the protein C antigen levels in the sample. This test is essential for determining whether a patient has a deficiency in protein C, which is critical for evaluating their risk for conditions such as venous thromboembolism.