PROTEIN S

These tests measure the levels of protein C and protein S in your blood. Protein C and protein S tests are two separate tests that are often done at the same time.

Protein C and protein S work together to prevent your blood from clotting too much. Normally, your body makes blood clots to stop bleeding after a cut or other injury. If you don’t have enough protein C (protein C deficiency) or enough protein S (protein S deficiency), your blood can clot more than you need it to. If this happens, you may get a clot that partly or completely blocks blood flow in a vein or artery. These clots can form in the arms and legs and travel to your lungs. When a blood clot forms in the lungs it’s called a pulmonary embolism. This condition is life-threatening.

Protein C and protein S deficiencies can be mild or severe. Some people with mild deficiencies never have a dangerous blood clot. But certain factors can increase the risk. These include surgery, pregnancy, certain infections, and extended periods of inactivity, such as being on a long airline flight.