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Protein C Deficiency

Inherited or acquired thrombophilia due to deficiency of the natural anticoagulant protein C.

Written by: Saygı Hospital Health Guide Editorial Board
Last updated:

This content has been compiled by the Saygı Hospital Health Guide Editorial Board and is periodically reviewed by a specialist physician.

This content is for informational purposes only and does not constitute medical advice. You can book an appointment at our Hematoloji department. Book Appointment →

What is Protein C Deficiency?

Protein C is a vitamin K-dependent natural anticoagulant produced in the liver. Activated by thrombin-thrombomodulin complex, activated protein C (APC) cleaves and inactivates factors Va and VIIIa, dampening coagulation. Protein C deficiency reduces this anticoagulant activity, producing a hypercoagulable state.

Two laboratory phenotypes are distinguished: type I (quantitative) with reduced antigen and activity, and type II (qualitative) with normal antigen but reduced activity. Inheritance is autosomal dominant; heterozygous carriers (~1 in 200-500) have moderately increased venous thromboembolism risk; rare homozygous or compound heterozygous infants present with neonatal purpura fulminans, devastating thrombotic skin necrosis requiring emergency replacement and lifelong anticoagulation.

Acquired protein C deficiency is more common: liver disease, vitamin K antagonist therapy (warfarin), disseminated intravascular coagulation, sepsis, post-surgical states, and acute thrombosis itself can lower levels. Diagnosis must be performed at a stable baseline, off anticoagulation (especially warfarin), and not during acute thrombosis. Heterozygotes present with VTE typically in young adulthood; combined deficiency with factor V Leiden or prothrombin G20210A markedly increases risk. Warfarin initiation without bridging may cause warfarin-induced skin necrosis due to rapid protein C drop before factor II/X reduction. Management: anticoagulation for thrombosis, careful warfarin initiation with heparin/LMWH bridge, lifelong anticoagulation in recurrent or unprovoked VTE, family screening, genetic counseling, and pregnancy management with LMWH.

Symptoms

Most heterozygotes asymptomatic until precipitant
Deep vein thrombosis (leg swelling, pain)
Pulmonary embolism (sudden dyspnea)
Cerebral venous thrombosis
Mesenteric or portal vein thrombosis
Recurrent venous thromboembolism, often young age
Warfarin-induced skin necrosis (centripetal areas — breast, thigh, abdomen — within first days of warfarin)
Neonatal purpura fulminans (homozygous)
Stillbirth, recurrent miscarriage (debated)
Family history of VTE
Pregnancy-related VTE
Hormonal contraceptive-related VTE
Postoperative VTE despite prophylaxis
Surface skin necrosis at injection sites
Severe sepsis with disproportionate microvascular thrombosis

Risk Factors

Heterozygous protein C deficiency (autosomal dominant)
Homozygous or compound heterozygous (severe neonatal)
Family history of VTE
Combined thrombophilia (factor V Leiden, prothrombin G20210A)
Estrogen-containing contraceptives, HRT
Pregnancy and postpartum
Surgery, immobilization, trauma
Cancer
Antiphospholipid syndrome (compound risk)
Liver disease (acquired)
Sepsis, DIC (acquired)
Warfarin therapy (lowers protein C)
Vitamin K deficiency
Newborn (transient deficiency, rule out true)
Inflammatory bowel disease, nephrotic syndrome (acquired)

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

  • Personal VTE in young adult, unprovoked, or recurrent
  • Family history of VTE in young relatives
  • Warfarin-induced skin necrosis in current or past patient
  • Neonatal purpura fulminans
  • Pre-pregnancy counseling with known protein C deficiency
  • Considering hormonal contraception or HRT with protein C deficiency
  • Major surgery in known carrier
  • Unusual-site thrombosis

Treatment Methods

01
Hematology referral
02
Test indications: first VTE in young patient, unprovoked VTE, recurrent, family history, pregnancy planning, warfarin skin necrosis
03
Test at stable baseline (≥2 weeks off warfarin, away from acute thrombosis); plasma protein C activity by chromogenic or clot-based assay
04
If reduced, repeat to confirm; antigen for type I vs II distinction; consider genetic testing in research or atypical cases
05
Family screening guided by symptomatic family member; pre-test and post-test counseling
06
Acute VTE: anticoagulate with LMWH, fondaparinux, or DOAC; if warfarin used, bridge with parenteral anticoagulant until INR therapeutic for ≥5 days to prevent warfarin-induced skin necrosis
07
Long-term anticoagulation: 3 months for provoked first VTE; extended/indefinite for unprovoked, recurrent, or homozygous; DOAC, warfarin, or LMWH options
08
Avoid combined estrogen-progestin contraceptives in carriers with VTE; progestin-only or non-hormonal preferred
09
Pregnancy: LMWH antepartum and postpartum prophylaxis in those with prior VTE, family history, or homozygous; otherwise risk-based
10
Surgical prophylaxis: standard VTE prophylaxis with extended duration in major orthopedic and abdominal surgery
11
Neonatal homozygous purpura fulminans: emergency protein C concentrate (Ceprotin) IV, FFP if not available; lifelong anticoagulation; transition to liver transplantation in selected cases
12
Combined thrombophilia (protein C + factor V Leiden, etc.) implies higher risk and often indefinite anticoagulation
13
Avoid warfarin alone without parenteral bridge in protein C deficient patient
14
Patient education on hormonal therapy, pregnancy planning, surgery preparation, VTE warning signs
15
Family planning, genetic counseling for offspring, partner screening if both parents heterozygous (homozygous offspring risk)
16
Long-term follow-up: post-thrombotic syndrome surveillance, recurrent VTE, anticoagulant adherence, bleeding risk
17
Vaccinations and general health maintenance
18
Pregnancy: multidisciplinary care, fetal monitoring, anticoagulation through delivery and 6 weeks postpartum
19
Avoid IM injections with anticoagulation
20
Lifestyle: smoking cessation, weight management, hydration, avoid prolonged immobilization
21
Multidisciplinary care: hematology, obstetrics, surgery, neonatology if homozygous

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You can visit our Hematoloji department for these complaints. Our specialist physicians will create the most suitable treatment plan for you.

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Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.