Protein S Deficiency

 

I. Review of Protein S

II. Congenital deficiency of Protein S

A. Inheritance is autosomal dominant.  Homozygotes often develop neonatal purpura fulminans shortly after birth. Heterozygotes can also develop thrombosis.

B. There are two types of congenital Protein S deficiencies

1. Type I - Decreased free Protein S, but adequate bound levels.

2. Type II - Decreased free and bound Protein S.

C. Clinical features are similar to Protein C Deficiency

1. 50% will have first thrombotic event before age 25

2. 44% will have other provocations, while the remaining 56% will have spontaneous thrombosis.

3. Arterial thrombosis is not increased.

III. Acquired deficiency of Protein S

A. Seen in consumptive processes such as DIC or extensive DVT/PE.

B. Seen in patients taking warfarin. (Other Vitamin K-dependent factors also decrease with warfarin treatment.)

1. After starting warfarin, Proteins C&S drop to 40-60% within 48 hours and increase to 70% after 2 weeks.

2. Therefore, assays to measure Proteins C&S may yield false values if not performed several weeks after intiation of warfarin treatment.

C. In pregnancy, both free and bound Protein S is decreased.

D. Also seen in liver disease.

 

IV. Treatment

A. Heparin for acute thrombosis.
B. Maintenance anticoagulation with warfarin or low dose subcutaneous heparin.
C. Prophylactic heparin during pregnancy and delivery.
D. Peri-operative prophylaxis with heparin.

 

 

 

Go to Antithrombin III Deficiency

 

Go to Protein C Deficiency

 

Go to Activated Protein C Resistance

 

Go to Antiphospholipid Syndrome

 

Go Back to Hypercoagulable States

 

Go to Prothrombin 20210 Defect

 

 

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