What is Protein C?
Protein C is a glycoprotein that works directly with Protein S to regulate blood clotting. If thromboembolism or deep vein thrombosis has occurred, the Protein C Functional Activity test along with other protein-based blood tests will be ordered within 10 days of the event. After 10 days the results are no longer considered accurate. Test results will also be inaccurate if the patient is currently taking medications to regulate blood clotting. Protein C and Protein S tests are always run simultaneously.

Normal Value Range

  • Negative Pregnancy Adult: 70 to 130 percent
  • Pregnancy Trimester One: 78 to 121 percent
  • Pregnancy Trimester Two: 83 to 133 percent
  • Pregnancy Trimester Three: 67 to 135 percent

Decreased protein C levels may mean the patient is suffering from an autoimmune disorder or severe infection. Some inherited conditions can cause decreased production of Protein C.

Pregnancy women suspected of suffering preeclampsia will undergo blood tests, including the Protein C Functional Activity Test. If Protein C levels are low, other signs of preeclampsia are evident and no other contributing factor(s) can be found, the patient will likely be admitted to the hospital (if not already) and labor induced or a C-section performed.

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