What You Should Know About Protein C Deficiency

Medically reviewed by Natalie Butler, RD, LD on November 3, 2016Written by Neel Duggal on November 3, 2016

What is protein C deficiency?

Protein C is a protein produced by the liver. It’s found in low concentrations in the blood stream. It’s inactive until vitamin K activates it.

Protein C serves a variety of functions. Its main function is preventing blood from clotting. If you’re deficient in protein C, your blood is more likely to clot than someone with normal levels. Higher than normal levels of protein C aren’t associated with any known health issues. But it may increase bleeding.

Protein C deficiency is found in similar levels in both men and women, and among different ethnicities.

What are the symptoms of protein C deficiency?

In some cases, someone with protein C deficiency may not display clotting issues or other symptoms. Other times, a deficiency in protein C can lead to high levels of blood clotting.

Blood clotting can be linked to various conditions:

  • Deep vein thrombosis (DVT): Clots in the leg veins can cause pain, swelling, discoloration, and tenderness. The severity usually depends on the extent of the clot. If the DVT isn’t in a leg, you may not have any noticeable symptoms.
  • Pulmonary embolism (PE): PE can lead to chest pain, fever, dizziness, coughing, and shortness of breath.
  • Neonatal purpura: This condition is seen in newborn babies. Symptoms appear within 12 hours after birth and include skin lesions that start out dark red and then become purple-black.
  • Thrombophlebitis: This condition causes inflammation and redness along the affected part of the vein.

Each of these conditions has its own unique symptoms.

People with protein C deficiency have an increased risk for DVT and PE.

Learn more: How to tell if you have a blood clot »

What causes protein C deficiency?

Protein C deficiency can be inherited, acquired, or develop over time as the result of other conditions.

Protein C deficiency is caused by genetics, or inherited. That means you’re more likely to develop it if you have a family history of protein C deficiency. You have a 50 percent chance of developing it if one of your parents has protein C deficiency. About 1 in 500 people, or 0.2 percent of the general population has protein C deficiency.

You can also develop a protein C deficiency without a genetic link. Conditions that can lead to a protein C deficiency include:

  • vitamin K deficiency
  • use of blood thinners such as warfarin (Coumadin, Jantoven)
  • liver failure
  • widespread metastatic tumors
  • severe illness, including infection
  • disseminated intravascular coagulation

Acquired decrease in protein C levels is not clinically significant in the way that inherited protein C deficiency is.

How is it diagnosed?

Testing for protein C is quick and easy. Your doctor will take a simple blood draw and then run a test to determine the level of protein C in your blood. A doctor should do the testing several weeks after a blood clot episode, and after you’ve stopped taking certain blood thinning medications, such as warfarin (Coumadin, Jantoven).

Your doctor may perform blood tests because false-positives are common.

Protein C deficiency and pregnancy

Women with protein C deficiency have a higher risk of developing clots both during and after pregnancy. That’s because pregnancy is a risk factor for developing blood clots.

Researchers believe that protein C deficiency may increase the risk for miscarriages in the early and late terms of pregnancy. Talk to your doctor if you think you are at risk for protein C deficiency. Together you can come up with a plan for a safe pregnancy and delivery.

How can you treat protein C deficiency?

Blood thinner medications, also known as anticoagulants, can treat protein C deficiency. These medications cut your risk for blood clot formation by preventing blood from clotting in blood vessels. The medication won’t allow the clots to get bigger, and won’t break up clots that have already formed.

Blood thinners include heparin (Hep-Lock U/P, Monoject Prefill Advanced Heparin Lock Flush), which is injected, and warfarin (Coumadin, Jantoven), direct oral anticoagulants taken by mouth. A treatment plan may include injecting heparin into your skin for the first week, and then taking an oral medication after the first week.

What’s the outlook?

Protein C deficiency isn’t common. If you have a deficiency, your outlook is positive. Many people with protein C deficiency don’t have notable side effects. If clotting is an issue, there are many ways to manage and prevent it by doing the following:

  • taking proper medications
  • maintaining a healthy lifestyle
  • being proactive about your condition

Tips for prevention

You may not be able to prevent a protein C deficiency, but you can take steps to reduce your risk for blood clots:

  • Exercise regularly.
  • Take all medications prescribed by your doctor.
  • Wear socks called “compression stockings” if your doctor prescribes them.
  • Avoid standing or sitting for prolonged periods of time.
  • Stay hydrated. Drink plenty of water throughout the day.

Also, if you have a family history of protein C deficiency or blood clotting, talk with your doctor about a prevention plan. Being proactive is your best step for prevention.

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