51: Prtn S Deficiency - Yoho

Question 1

Define Protein S

Answer 1

vitamin K dependent glycoprtn

• Found in vasculature (free floating or bound in prtn C)
• Prtn C cofactor that inactivates extrinsic pathway factors 5 and 8
• Manufactured in Liver
• S = Seatle, discovered in 1970s

Question 2

What are the etiologies of Prtn S deficency?

Answer 2

– Congenital: inheritance is autosomal dominant; homozygotes develop neonatal purpura fulminans shortly after birth; and heterozygotes. Three types:
§ Inadequate amounts of prtn S in both free and bound forms
§ Characterized as defective prtn molecules
§ Decreased free ptn S, but overall normal amount of prtn S

	– Acquired: Seen in consumptive processes like DIC or extensive DVT/PE; patients taking warfarin (other Vit K dependent factors); pregnancy; liver disease

Question 3

Identify consequences of a prtn S deficiency

Answer 3

– DVT = VTE (50% first thrombotic event before age 25) 44% with provocation 56% spontaneous

– Possible association with arterial thrombosis (stroke, heart attack) under investigation

Question 4

Demonstrate the approach in the management of a pt with a prtn S deficiency.

Answer 4

• Immunoassay test for Prtn S deficiency
• Liver profile and CBC with diff
• PTT and PT to check bleeding times
• No tourniquet, minimal surgery time, prophylactic anticoagulant therapy, early range of motion, monitor, good history taking skills