What are the uses of vitamin K (Vit K) injections in patients, including newborns and those with liver disease or taking anticoagulant medications like warfarin (coumarin)?

Vitamin K Injection Uses

Vitamin K injections are primarily used to prevent life-threatening bleeding in newborns (vitamin K deficiency bleeding/VKDB), reverse warfarin-associated hemorrhage, and treat bleeding in patients with fat malabsorption syndromes or severe vitamin K deficiency. 1, 2

Primary Clinical Indications

Newborn Prophylaxis

• All newborns should receive vitamin K at birth to prevent VKDB, which can cause devastating intracranial hemorrhage and death. 2
• Newborns have physiologically low levels of vitamin K-dependent clotting factors (II, VII, IX, X) compared to adults, making them inherently vulnerable to bleeding disorders. 1, 2
• The recommended dose is 0.5-1.0 mg intramuscular (IM) as a single injection at birth. 3, 4
• Exclusively breastfed infants are at particularly high risk because breast milk contains very low concentrations of vitamin K. 1, 2, 5
• A single IM injection effectively prevents both classic VKDB (first week of life) and late VKDB (2 weeks to 3 months of age). 6, 3

Important caveat: Oral vitamin K is inferior to IM administration and requires multiple doses using products not FDA-approved for neonatal oral use. 6, 5 If parents decline IM vitamin K, oral dosing (2 mg at birth, repeated at 2-4 and 6-8 weeks) should be offered with clear counseling about increased VKDB risk. 3, 4

Warfarin Reversal and Hemorrhage Management

• For warfarin-associated intracranial hemorrhage, administer vitamin K 10 mg IV immediately along with prothrombin complex concentrates to ensure durable INR reversal. 2
• For minor bleeding progressing to major hemorrhage, give 5-25 mg (rarely up to 50 mg) parenteral vitamin K. 7
• Never exceed 10 mg per dose in routine reversal, as higher doses create a prothrombotic state and prevent re-anticoagulation for days. 2
• Maximum effect for IV administration occurs at 6-12 hours, while oral supplementation takes approximately 24 hours. 8

Critical warning: Avoid vitamin K reversal when intracranial hemorrhage is suspected due to cerebral venous thrombosis, as reversal may worsen thrombosis. 2

Vitamin K Deficiency Treatment

• The most common causes requiring treatment are fat malabsorption conditions (celiac disease, cystic fibrosis, short bowel syndrome), malnutrition, prolonged antibiotic use, and anticoagulant therapy. 8
• Vitamin K deficiency results in prolonged prothrombin time with impaired clotting or frank bleeding, confirmed by response to vitamin K administration. 8, 2
• Beyond hemostasis, deficiency contributes to poor bone development, osteoporosis, and increased cardiovascular disease risk. 8, 2

Special Populations

Preterm Infants

• Preterm infants on parenteral nutrition should receive 10 μg/kg/day of vitamin K. 1
• For high-risk neonates (premature, birth asphyxia, difficult delivery, hepatic disease), the first dose must be administered IM or slow IV route with repeated doses as needed. 9

Maternal Drug Exposure

• Infants whose mothers took medications interfering with vitamin K metabolism (anticonvulsants, anticoagulants, antituberculosis drugs) require prophylaxis. 1
• Antenatal maternal prophylaxis (10-20 mg/day orally for 15-30 days before delivery) prevents early VKDB in these cases. 9

Patients with Liver Disease

• In liver disease without cholestasis, vitamin K has minimal efficacy because the liver cannot synthesize clotting factors despite adequate vitamin K. 2
• Vitamin K is indicated when cholestasis or fat malabsorption is present. 8

Administration and Safety

Route Selection

• IV administration should be by slow injection to minimize risk of rare anaphylactoid reactions (3 per 100,000 doses) that can cause bronchospasm and cardiac arrest. 8, 2
• IM route is preferred for newborn prophylaxis. 3, 4
• Oral route is less effective and requires multiple doses. 6, 5, 3

Drug Interactions

• Patients on anti-vitamin K drugs should avoid sudden major changes in vitamin K intake and require monitoring with blood clotting tests. 8, 2
• Continuous enteral nutrition should be withheld for 1 hour before and after anticoagulant drug administration to prevent interactions. 8

Monitoring

• Classical coagulation tests (PT, PTT) can be used for indirect evaluation but are not specific to vitamin K deficiency. 1
• PIVKA-II (undercarboxylated vitamin K-dependent proteins) is a more useful biomarker for at-risk patients when locally available. 8, 1
• A prompt response (shortening of prothrombin time within 2-4 hours) following vitamin K administration is diagnostic of VKDB. 1

Toxicity Considerations

• Vitamin K1 (phylloquinone) and K2 are not associated with toxicity. 8, 1
• The synthetic vitamin K3 is very toxic (causes jaundice, hemolytic anemia, kernicterus) and is no longer available. 8