What are the recommended daily vitamin K intakes for healthy adult men and women, and the therapeutic dosing for vitamin K deficiency and for reversal of warfarin anticoagulation?

Vitamin K Dosage for Adults

For healthy adults, the recommended daily intake is 90 µg for women and 120 µg for men; for warfarin reversal with major bleeding, administer 5–10 mg IV vitamin K by slow infusion over 30 minutes plus 4-factor PCC; for elevated INR >10 without bleeding, give oral vitamin K 2.5–5 mg. 1, 2, 3

Daily Recommended Intake for Healthy Adults

Nutritional Requirements:

• Women: 90 µg/day of phylloquinone (vitamin K1) 4
• Men: 120 µg/day of phylloquinone 4
• These recommendations represent approximately a 50% increase from previous guidelines and are based on Institute of Medicine standards 4

Dietary Context:

• Average intake in young adults is approximately 80 µg/day, while older adults consume approximately 150 µg/day 5
• Most foods contain very low vitamin K concentrations (<10 µg/100 g), with the majority obtained from leafy green vegetables and four vegetable oils (soybean, cottonseed, canola, and olive) 5
• Intestinal bacteria synthesize vitamin K2 (menaquinones) but not K1, contributing to meeting requirements 1

Medical Nutrition Support Dosing

Enteral Nutrition:

• Provide at least 3.5–20 µg per 100 kcal, which generally meets recommended daily intake 1
• Important caveat: EN significantly impacts anticoagulation response in patients on vitamin K antagonists; interrupt EN 1 hour before and after anticoagulant administration 1

Parenteral Nutrition:

• Weekly IV supply of 250–500 µg phylloquinone from lipid emulsions is sufficient to restore and maintain normal plasma levels 1
• Adult multivitamin preparations provide an additional 150 µg, which covers requirements and maintains carboxylation status of non-coagulation proteins 1
• Critical warning: Doses exceeding 150 µg can cause vitamin K antagonist resistance in patients on warfarin 1

Therapeutic Dosing for Warfarin Reversal

Life-Threatening Bleeding or Emergency Surgery (Any INR)

Immediate reversal protocol:

• 4-factor PCC: 25 U/kg (INR 2–<4), 35 U/kg (INR 4–6), or 50 U/kg (INR >6) IV, maximum 5,000 U 1, 2, 3
• Plus vitamin K: 5–10 mg IV by slow infusion over 30 minutes 1, 2, 3
• Target INR: <1.5 1, 2, 3
• Onset: PCC corrects INR within 5–15 minutes; vitamin K sustains reversal because factor VII half-life is only 6 hours 2, 3

Major Bleeding (Non-Life-Threatening)

• Vitamin K: 5–10 mg IV by slow infusion over 30 minutes 1, 2, 3
• Consider adding PCC if bleeding occurs at critical sites (intracranial, intraspinal, intraocular, pericardial, retroperitoneal) or patient is hemodynamically unstable 2, 3

Elevated INR Without Bleeding

INR 4.5–10.0:

• Withhold warfarin for 1–2 doses and monitor serial INR 1, 2
• Add oral vitamin K 1–2.5 mg only if high-risk bleeding factors present (age >65–75 years, prior bleeding, concurrent antiplatelet therapy, renal failure, or alcohol use) 1, 2
• Evidence note: Pooled analysis of 4 RCTs showed no reduction in major bleeding with routine vitamin K (2% vs 0.8% placebo) despite faster INR normalization 1

INR >10.0:

• Immediately stop warfarin and give oral vitamin K 2.5–5 mg 1, 2
• Recheck INR within 24 hours 1, 2
• If active bleeding develops, add PCC 50 U/kg IV plus vitamin K 5–10 mg IV 2

Route of Administration Considerations

Intravenous (for active bleeding):

• Dilute in 25–50 mL normal saline and infuse slowly over 15–30 minutes (never >1 mg/min) 2, 3
• Achieves partial INR correction within 4–6 hours 2
• Anaphylactoid risk: 3 per 100,000 doses; slow infusion minimizes this risk 2, 3

Oral (for non-emergency situations):

• Preferred route for asymptomatic elevated INR 2
• Achieves predictable effectiveness with 95% of patients showing INR reduction within 24 hours 2
• Takes 18–24 hours to reach full effect versus 4–6 hours for IV 2

Subcutaneous:

• Not recommended due to unpredictable absorption 2

Critical Dosing Caveats

Maximum dose ceiling:

• Never exceed 10 mg in non-bleeding situations; higher doses create a prothrombotic state and prevent re-warfarinization for up to one week 2, 3

Mechanical heart valve patients:

• Use low-dose oral vitamin K (1–2 mg) when feasible to avoid difficulty achieving therapeutic INR post-procedure 2, 3
• For intracranial hemorrhage, rapid reversal is mandatory despite thrombosis risk 2

Thrombotic risk:

• PCC use increases venous and arterial thrombosis risk; consider thromboprophylaxis as early as possible after bleeding control 1, 2

Common Pitfalls to Avoid

• Do not give vitamin K routinely for INR 4.5–10 without bleeding unless high-risk factors present; this is a Grade 2B recommendation 1
• Do not use subcutaneous vitamin K for active bleeding scenarios due to unpredictable absorption 2
• Do not delay PCC administration while awaiting laboratory confirmation in life-threatening bleeding 2
• Do not use vitamin K alone for life-threatening bleeding; it requires 4–6 hours to lower INR, necessitating PCC for immediate correction 2, 3
• Avoid high-dose vitamin K (≥10 mg) in asymptomatic patients with elevated INR; this induces warfarin resistance lasting up to one week 2