Quick Facts
- Sample: Blood (plasma in green-top anticoagulated tube)
- Fasting: 12-hour fast required
- Turn-around: 10 business days. May take longer based on weather, holiday, or lab delays.
Benefits
- Detect deficiency early - identify low Vitamin K1 before bleeding or bone complications develop
- Highly accurate - uses advanced LC-MS/MS technology for precise plasma quantification
- Support clotting & bone health - assess your status to optimize blood coagulation and skeletal strength
- Monitor risk factors - ideal if you have liver disease, malabsorption, or take certain medications
Who Is This Test For?
- Individuals with malnutrition or restrictive diets low in leafy greens
- People with liver disease, biliary obstruction, or cystic fibrosis
- Those experiencing prolonged antibiotic therapy that disrupts gut bacteria
- Patients on anticoagulants like warfarin needing vitamin status monitoring
- Anyone with unexplained bruising, bleeding disorders, or bone health concerns
- Adults assessing nutritional deficiencies alongside comprehensive metabolic panels
How It Works – Just 3 Steps
- Order online - complete your purchase and receive a lab requisition instantly
- Visit a local lab - fast for 12 hours, then have blood drawn at any participating facility
- Get results securely - access confidential findings in 10 business days
FAQ
What does this test measure? Plasma phylloquinone (Vitamin K1) concentration using liquid chromatography tandem mass spectrometry. (Mayo Clinic 2024)
Why is fasting required? A 12-hour fast ensures accurate baseline levels without interference from recent Vitamin K-rich meals or supplements.
Will my medications affect results? Yes—antibiotics, warfarin, and cholestyramine can alter Vitamin K metabolism; inform your provider before testing.
Can I take supplements before the test? Avoid Vitamin K supplements for at least 24 hours prior to ensure accurate measurement.
How quickly will I receive results? Typical turnaround is 10 business days after the lab receives your refrigerated, light-protected sample.
More Details
What is the purpose of this test?
The Vitamin K1 Blood Test measures plasma concentrations of phylloquinone, a fat-soluble vitamin essential for synthesizing coagulation factors that prevent excessive bleeding. Vitamin K also supports bone metabolism by activating proteins that bind calcium to bone tissue and regulate vascular health. This test identifies deficiency that can impair blood clotting, increase fracture risk, and contribute to vascular calcification. By quantifying Vitamin K1 levels, healthcare providers can diagnose deficiency caused by malnutrition, malabsorption syndromes, liver disease, or prolonged antibiotic use. (NIH Office of Dietary Supplements 2025)
Who would benefit from this test?
This test is valuable for individuals at elevated risk of Vitamin K deficiency. Those with malabsorption disorders—including Crohn's disease, celiac disease, inflammatory bowel disease, or cystic fibrosis—often cannot adequately absorb fat-soluble vitamins. People with liver disease or biliary obstruction may have impaired Vitamin K metabolism or bile secretion necessary for absorption. Patients on long-term antibiotic therapy face disrupted intestinal bacteria that normally synthesize some Vitamin K. Additionally, individuals taking anticoagulants like warfarin benefit from monitoring to balance medication efficacy with vitamin status. (American Society of Hematology 2023) Those with unexplained bleeding, easy bruising, or compromised bone health should also consider testing.
When should I order a Vitamin K1 Blood Test?
Order this test when clinical signs suggest deficiency or when you have risk factors that impair Vitamin K absorption or metabolism. Key indicators include unexplained or excessive bleeding, easy bruising, heavy menstrual periods, slow wound healing, or bone fragility. Testing is recommended if you have chronic liver disease, inflammatory bowel conditions, or have undergone bariatric surgery. Patients on prolonged antibiotic regimens or anticoagulant therapy should monitor levels periodically. (CDC 2025) Additionally, individuals following restrictive diets lacking leafy greens, vegetable oils, and fermented foods—primary dietary sources—may benefit from baseline assessment to prevent deficiency-related complications.
How do I interpret the results?
Vitamin K1 plasma levels are compared against reference ranges established for healthy adults. Low levels indicate deficiency that can compromise coagulation and bone mineralization, requiring dietary modification or supplementation. Normal levels suggest adequate intake and absorption. Because Vitamin K is fat-soluble and transported by lipoproteins, results should be interpreted alongside lipid profiles. Your healthcare provider will correlate findings with clinical symptoms, coagulation tests (like PT/INR), and medical history for comprehensive assessment.
Low (<0.2 ng/mL)
- Meaning: Deficiency; increased bleeding and bone fracture risk
- Typical action: Dietary counseling, oral supplementation, investigate underlying causes
Normal (0.2–3.0 ng/mL)
- Meaning: Adequate status for coagulation and bone health
- Typical action: Maintain a balanced diet rich in leafy greens and healthy fats
High (>3.0 ng/mL)
- Meaning: Elevated intake from diet or supplements
- Typical action: Review supplementation; generally not harmful but reassess dosage
Vitamin K deficiency affects up to 25% of hospitalized or malnourished patients, making early detection critical for preventing hemorrhagic complications. (NIH 2025)
Disclaimer: Reference ranges may vary by laboratory. Listed ranges are general guidelines and may differ from those used by the performing lab. Always consult your healthcare provider for interpretation.
Pre-test preparation
Fast for 12 hours before your blood draw to ensure accurate baseline measurement. Avoid consuming Vitamin K-containing foods—including kale, spinach, broccoli, Brussels sprouts, and fortified cereals—during the fasting period. Discontinue Vitamin K supplements at least 24 hours prior to testing unless otherwise directed by your healthcare provider. Inform the lab if you take medications that affect Vitamin K metabolism, such as warfarin, antibiotics, cholestyramine, or rifampin. Blood is collected in a green-top anticoagulated tube, then refrigerated and protected from light during transport to preserve sample integrity. (Labcorp 2024)
How often should I get tested?
Testing frequency depends on your medical condition, risk factors, and treatment regimen. Consult your healthcare provider to establish a personalized monitoring schedule based on your specific circumstances.
- Baseline screening for at-risk individuals: Once initially, then as clinically indicated
- Active malabsorption disorders (IBD, celiac disease): Every 6–12 months or with symptom changes
- Chronic liver disease or biliary obstruction: Every 6–12 months during treatment monitoring
- Long-term antibiotic or anticoagulant therapy: Every 3–6 months or per physician recommendation
- Post-supplementation or dietary intervention: Retest after 3 months to assess response
Why early detection matters
Vitamin K deficiency can progress silently until serious complications emerge, including uncontrolled bleeding, hemorrhagic stroke, or debilitating fractures. Early identification allows timely intervention through dietary modification or supplementation before coagulation proteins become critically low. Monitoring is especially important for newborns at risk of hemorrhagic disease, individuals with fat malabsorption syndromes, and patients on anticoagulants where deficiency could paradoxically increase bleeding risk. (CDC 2025) Adequate Vitamin K status also supports cardiovascular health by preventing arterial calcification. Proactive testing empowers you to maintain optimal levels, reducing complications and supporting long-term health outcomes.
Related tests you may consider
Prothrombin Time (PT) w/INR Blood Test - Used to diagnose bleeding or clotting disorders and to determine if a medication that prevents blood clots is effective.
Vitamin D 25-Hydroxy Blood Test - Checks if you have enough vitamin D, helping to ensure your bones stay healthy and reducing the risk of various health issues associated with vitamin D deficiency.
Complete Blood Count (CBC) and Comprehensive Metabolic Panel (CMP-14) Blood Test Panel- Used to diagnose and monitor health conditions by evaluating blood cells, liver and kidney function, and detecting diabetes.
Lipid Panel Blood Test - Measures the amount of good and bad cholesterol to assess risk of cardiovascular disease such as heart disease, heart attack and stroke.
