Vitamin K1 (phylloquinone) is a fat-soluble vitamin primarily obtained from dietary green leafy vegetables and serves as an essential cofactor for the hepatic gamma-carboxylation of coagulation factors II, VII, IX, and X, as well as the anticoagulant proteins C and S. Serum or plasma phylloquinone levels reflect recent dietary intake more than total body stores, making it a useful but context-dependent biomarker. Laboratory measurement is typically performed by high-performance liquid chromatography (HPLC) with fluorescence or mass spectrometric detection. Phylloquinone is absorbed in the small intestine via a carrier-mediated process requiring bile salts and pancreatic enzymes, then transported in chylomicrons to the liver where it undergoes recycling through the vitamin K epoxide reductase complex (VKORC1) to sustain carboxylation reactions. Adequate vitamin K1 activity is essential for maintaining hemostatic balance, as deficiency impairs synthesis of functional clotting factors and leads to a prolonged prothrombin time (PT/INR). Vitamin K1 also plays a role in bone metabolism through carboxylation of osteocalcin and matrix Gla protein, though this function is more closely associated with vitamin K2 (menaquinone) in extrahepatic tissues.
Vitamin K1 is a nutrient found mainly in green leafy vegetables that helps your blood clot properly and supports bone health. This test measures how much vitamin K1 is circulating in your blood, which mainly reflects what you have eaten recently. Low levels can make it harder for your blood to clot, increasing the risk of bleeding, while very high levels are usually harmless but can interfere with blood-thinning medications like warfarin. Your doctor may order this test if you have unexplained bleeding, are on certain medications, or have a condition that affects how your body absorbs fats and nutrients.
When elevated: Elevated vitamin K1 levels are most commonly seen with recent high dietary intake of green leafy vegetables or vitamin K supplementation and are generally not clinically harmful. In patients on vitamin K antagonist therapy (e.g., warfarin), elevated phylloquinone can reduce anticoagulant efficacy and lead to subtherapeutic INR values, increasing thromboembolic risk in those requiring anticoagulation. When low: Low vitamin K1 levels are associated with impaired gamma-carboxylation of coagulation factors, potentially resulting in a bleeding diathesis characterized by prolonged PT/INR and, in severe cases, spontaneous hemorrhage. Deficiency may also impair carboxylation of bone and vascular Gla proteins, with potential long-term implications for bone mineral density and vascular calcification, though these associations require further clinical validation.
Vitamin K1 is not a primary performance biomarker for athletes, but supports recovery and injury resilience through blood clotting regulation and bone health. Athletes with high injury risk, those taking anticoagulants, or those with malabsorption issues (affecting fat-soluble vitamin uptake) may benefit from monitoring adequate K1 intake via leafy greens, though routine testing is rarely necessary for healthy athletes.
Turnaround Time
3 days (up to 7 days)
Fasting Required
No
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$97.00
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