What are the causes of elevated vitamin K levels in adults?

Causes of Elevated Vitamin K in Adults

Elevated vitamin K levels in adults are primarily caused by excessive supplementation (particularly from parenteral or enteral nutrition) and high dietary intake of vitamin K-rich foods, though natural vitamin K1 and K2 are not associated with toxicity. 1

Primary Causes of Elevated Vitamin K Levels

Medical Nutrition Support

Parenteral nutrition (PN) is the most significant iatrogenic cause of elevated vitamin K:

• Lipid emulsions in PN contain phylloquinone concentrations ranging from 6 µg to 300 µg per 100 g of lipid material 2
• Weekly intravenous supply of 250-500 µg phylloquinone from PN lipids alone can restore and maintain plasma vitamin K concentrations 2
• Adult multivitamin preparations added to PN contribute an additional ~150 µg of vitamin K 2
• Critical caveat: In patients on warfarin, PN lipid-derived vitamin K doses exceeding 150 µg can lead to anticoagulant resistance 2

Enteral nutrition (EN) contributes moderate amounts:

• Standard EN formulas deliver approximately 3.5-20 µg per 100 kcal 2
• This generally meets recommended daily intake but can accumulate with continuous feeding 2
• In warfarin-treated patients, EN can markedly affect anticoagulation response, requiring dosing adjustments 2

Excessive Supplementation

Therapeutic or prophylactic vitamin K supplementation can elevate levels:

• Adult dosing ranges from 2.5-10 mg for most indications, with up to 25-50 mg for severe cases 2
• Recommended PN dosing is 200 µg/day for adults 2
• Daily supplementation accumulates due to vitamin K's storage in tissues 1

High Dietary Intake

Consumption of vitamin K-rich foods can elevate circulating levels:

• Leafy greens, cruciferous vegetables, asparagus, prunes, peas, and parsley are abundant sources of vitamin K1 1
• Fermented cheeses are major sources of vitamin K2 (menaquinones MK4-MK13) 3, 4
• Full-fat dairy products and fermented dairy also provide K2 3

Clinical Significance and Safety Profile

Importantly, vitamin K1 (phylloquinone) and vitamin K2 (menaquinones) are not associated with toxicity: 1, 3

• No known adverse effects from supplementation with natural forms 1
• The body does not accumulate toxic levels from dietary or supplemental sources 1
• Exception: Synthetic vitamin K3 (menadione) is very toxic and can cause jaundice, hyperbilirubinemia, hemolytic anemia, and kernicterus in infants 1

Rare Adverse Reactions

• Anaphylactoid reactions with bronchospasm and cardiac arrest have been reported after IV vitamin K1 (phytonadione) administration for anticoagulation reversal 1
• These reactions are extremely rare and related to the route of administration, not elevated levels per se 1

Critical Clinical Considerations

The primary concern with elevated vitamin K is interference with anticoagulation therapy, not toxicity:

• Patients on warfarin or other vitamin K antagonists must maintain consistent vitamin K intake 3
• Sudden increases in vitamin K can overcome warfarin's effect, requiring coagulation monitoring 3
• Vitamin K doses >150 µg can cause anticoagulant resistance in patients on vitamin K antagonists 1, 2

Monitoring vitamin K status:

• Circulating phylloquinone (vitamin K1) in plasma/serum is the most used marker, though it primarily reflects short-term intake 1
• Concentrations <0.15 mg/L indicate deficiency; there is no established upper limit for toxicity 1
• PIVKA-II (undercarboxylated prothrombin) can assess functional vitamin K status but is not routinely used 1