Protein C, Functional with Reflex to Protein C, Total and Protein S, Free with Reflex to Protein S, Total

Casandra

Casandra Test Code AR78719Version 1 (DRAFT)

Performing Lab

Lab ARUP LaboratoriesLab Test ID 2003386CPT Codes 85302, 85303, 85305, 85306

Protein C, Functional with Reflex to Protein C, Total and Protein S, Free with Reflex to Protein S, Total

Also known as: PROT C/S R

Clinical Use

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Use

This test is used to detect and subtype deficiencies in proteins C and S, which are important in regulating blood coagulation. Deficiencies in these proteins can lead to a hypercoagulable state, increasing the risk of thrombosis. Protein C, a vitamin K-dependent serine protease, plays a crucial role in inactivating coagulation factors Va and VIIIa. Protein S acts as a cofactor to Protein C, enhancing its anticoagulant effect. Identifying deficiencies in these proteins helps in diagnosing thrombotic disorders and can guide anticoagulant therapy management strategies.

Special Instructions

For accurate measurement, patients should not be on warfarin therapy for two weeks prior to testing, as this can interfere with protein C and S levels. Separate specimens must be submitted when multiple tests are ordered to ensure the integrity of samples for accurate results. The test requires careful adherence to collection and stability instructions to avoid erroneous results from sample degradation.

Limitations

The test may not be accurate in the presence of anticoagulant therapy such as heparin, direct thrombin inhibitors, or factor Xa inhibitors. It may also not differentiate between inherited and acquired deficiencies of protein C and S. Interpretation of low values should consider potential causes like liver disease, acute thrombosis, or other medical interventions. Repeat testing is recommended if initial low results are acquired under such conditions, after excluding acquired causes.

Test Details

New York Approved