Coagulation

• Vitamin K deficiency and coagulopathy
  • Single dose of vitamin K followed by PT / INR after 12 - 24 hours
  • If coagulopathy persists, a second dose is administered in 48 - 72 hours
• Warfarin associated bleeding or supratherapeutic INR (see Table 1)
  • Management is determined by whether or not the patient is bleeding and the degree of INR elevation
    • If not associated with bleeding, hold warfarin dose(s)
    • If associated with bleeding, discontinue warfarin and administer vitamin K
      • Prothrombin complex concentrate (PCC) can be given for serious bleeding to provide rapid and full reversal
      • If PCC is not available, donor plasma can be administered

Table 1: management of warfarin (Chest 2012;141:e152S, Blood Adv 2018;2:3257)
Clinical setting	Management
Serious or life threatening bleeding Any INR	4 factor PCC Vitamin K (intravenous) Hold warfarin
No bleeding INR > 10	Vitamin K (oral) Hold warfarin
No bleeding INR 4.5 to 10	Hold warfarin Vitamin K (low dose, oral) is optional

A 7 day old boy presents with agitation, lethargy and poor feeding. He was born at term via spontaneous vaginal delivery. All postnatal supplements and vaccines were not administered due to parental refusal. The newborn was breastfed exclusively. His body is covered with ecchymoses. Complete blood count showed normocytic normochromic anemia, normal white blood cell count and mild thrombocytopenia. A transcranial ultrasound reveals hemorrhage in the left cerebral hemisphere. Which of the following abnormalities is likely to be seen in this patient?

1. Congenital protein C deficiency
2. Decreased factor VIII level
3. Factor V Leiden mutation
4. Prolonged partial thromboplastin time (PTT)
5. Prolonged prothrombin time (PT)

E. Prolonged prothrombin time (PT). The lack of postnatal vitamin K supplementation and exclusive breastfeeding increases risk of vitamin K deficiency, which usually results in prolonged PT. Answer A is incorrect because congenital protein C deficiency leads to an inability to inactivate clotting factors and control thrombin production and can be associated with thrombosis rather than bleeding. Answer B is incorrect because while decreased factor VIII level or hemophilia A can present with spontaneous intracranial hemorrhage in neonates, the lack of vitamin K supplementation and exclusive breast feeding are more likely to be associated with deficiency of vitamin K dependent coagulation factors. Answer C is incorrect because factor V Leiden mutation increases the likelihood of thrombosis, not bleeding. Answer D is incorrect because deficiency of vitamin K will impact its dependent factors II, VII, IX and X, with factor VII affected early due to short half life. In more advanced stages, PTT is expected to be prolonged as well.

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Reference: Vitamin K deficiency / warfarin use

A 68 year old woman with alcoholic hepatitis and advanced cirrhosis presents with ecchymoses. Partial thromboplastin time (PTT) is normal while prothrombin time (PT) is elevated. Complete blood count showed normocytic normochromic anemia, normal white blood cell count and mild thrombocytopenia. Which deficiency is the most probable cause of this clinical scenario?

1. Fibrinogen
2. Riboflavin
3. Vitamin A
4. Vitamin C
5. Vitamin K

E. Vitamin K. Vitamin K is essential for the synthesis of coagulation factors II, VII, IX and X, as well as the natural anticoagulants protein C and S. Patients with alcohol use disorders often have low dietary intake of vitamin K and may also have malabsorption. Vitamin K deficiency leads to prolonged PT, which measures the activity of the extrinsic and common pathways. Answers A - D are incorrect because hypofibrinogenemia, deficiency of riboflavin, vitamin A and vitamin C do not typically result in normal PTT and prolonged PT.

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Reference: Vitamin K deficiency / warfarin use