Protein C

PROTEIN C ANALYSIS

Why the Test is Performed

You may need this test if you have an unexplained blood clot, or a family history of blood clots. Protein C helps control blood clotting. A lack of this protein or problem with the function of this protein may cause blood clots to form in veins.

The test is also used to screen relatives of people who are known to have protein C deficiency. It may also be done to find the reason for repeated miscarriages.

Normal Results

Normal values are 60% to 150% inhibition.

Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or may test different samples. Talk to your provider about the meaning of your specific test results.

What Abnormal Results Mean

A lack (deficiency) of protein C can lead to excess clotting. These clots tend to form in veins, not arteries.
Protein C deficiency can be passed down through families (inherited). It can also develop with other conditions, such as:

• Chemotherapy use
• Disorder in which the proteins that control blood clotting become over active (disseminated intravascular coagulation)
• Liver disease
• Long-term antibiotic use
• Warfarin (Coumadin) use
• A problem such as a sudden blood clot in the lung may reduce the protein C level.
• Protein C level rises with age, but this does not cause any health problems.