Vitamin K1 levels: what's normal, high and low
A fat-soluble vitamin essential for blood clotting and bone health.
Medically reviewed by Youmna DiStefano, MD · Last reviewed September 2026
The short answer
Vitamin K1 is measured with a standard blood draw; no fasting is needed. A typical reference range is 0.100 – 2.20 ng/mL. At TestWell it's $36.99 all-in as Vitamin K, results in 5–7 business days, drawn at Quest or Labcorp. An out-of-range result is a prompt to look closer, not a diagnosis.
- Units
- ng/mL
- Sample
- Blood draw
- Fasting
- Not required
- Results
- 5–7 business days
- Price
- $36.99
- Labs
- Quest or Labcorp
Vitamin K1 Reference Range
These are the typical adult reference ranges used by major US labs. Your report will include the specific range used by the lab that processed your sample.
| Population | Range |
|---|---|
| age 18+ | 0.100 – 2.20 ng/mL |
Reference ranges are educational. Always interpret your result with the specific range printed on your lab report and discuss anything outside the range with a clinician.
Have a result in hand? analyze it with your AI assistant using these reviewed ranges, or run it through our explainer. Tools: look up another marker's range · convert lab units
What your Vitamin K1 result may mean
Can reflect fat-malabsorption disorders, antibiotic use, or anticoagulant therapy.
What a low Vitamin K1 means: causes, symptoms, next steps ↓Educational only — not a diagnosis. Many factors can influence a single result. Discuss anything that concerns you with a healthcare provider.
What does a low Vitamin K1 mean?
Low vitamin K1 (phylloquinone) reflects low intake of leafy greens or fat malabsorption — celiac or Crohn's disease, cystic fibrosis, cholestatic liver disease, bariatric surgery — and prolonged antibiotic courses that wipe out gut bacteria. Warfarin does not lower the level but blocks its use. The functional consequence is a prolonged PT/INR and bleeding tendency; the blood level itself swings with the last day's meals.
Common causes of a low Vitamin K1
- Low intake of leafy green vegetables
- Fat malabsorption: celiac disease, Crohn's, cystic fibrosis, pancreatic insufficiency, cholestasis
- Prolonged broad-spectrum antibiotics
- Bariatric surgery, very low-fat diets
- Newborns (routine vitamin K at birth prevents this)
Ordered from most to least common.
Symptoms that can go with it
- Easy bruising, nosebleeds, bleeding gums, heavy periods
- Often none
What clinicians usually check next
- PT/INR — the test that shows whether the deficiency matters
- Fat-soluble vitamins A, D and E; celiac antibodies, stool fat if malabsorption is suspected
- Dietary correction; supplementation under clinician guidance (and never without the prescriber's input if you take warfarin)
Follow-up tests at TestWell: PT and PTT (Prothrombin & Partial Thromboplastin Time) ($26.99).
Does a low vitamin K level mean I'll bleed?
Only if the PT/INR is prolonged. The blood level is a snapshot of recent intake; clotting tests show whether the body has enough to work with.
Educational only — not a diagnosis. A single result outside the range is a prompt to look closer with a clinician.
How do you get a Vitamin K1 test?
Order online, a licensed physician reviews the requisition, and you walk into a nearby lab for the draw. Vitamin K1 is available on its own or inside these panels — panels cost less per marker when you want the fuller picture.
| Option | Includes | Price |
|---|---|---|
| Vitamin K | This marker only | $36.99 |
Quest vs. Labcorp for Vitamin K1: which lab should you pick?
Both are CLIA-certified national labs and the result is clinically equivalent, so pick whichever location is closer. Your report will print that lab's own reference range, which can differ slightly from the table above.
| Lab | Available | Price |
|---|---|---|
| Quest Diagnostics | Yes | $36.99 |
| Labcorp | Yes | $36.99 |
| BioReference (NY & NJ) | No | — |
Need help choosing a location? Use the lab finder to see draw sites near your ZIP.
Related Vitamins & Nutrients biomarkers
Markers commonly tested alongside Vitamin K1.
Frequently asked
What does a low Vitamin K1 mean?
Low vitamin K1 (phylloquinone) reflects low intake of leafy greens or fat malabsorption — celiac or Crohn's disease, cystic fibrosis, cholestatic liver disease, bariatric surgery — and prolonged antibiotic courses that wipe out gut bacteria. Warfarin does not lower the level but blocks its use. The functional consequence is a prolonged PT/INR and bleeding tendency; the blood level itself swings with the last day's meals.
Does a low vitamin K level mean I'll bleed?
Only if the PT/INR is prolonged. The blood level is a snapshot of recent intake; clotting tests show whether the body has enough to work with.
Do I need a doctor's order to test my vitamin k1?
No. TestWell's licensed physician network reviews and approves your order — usually within minutes. You can place an order online without an in-person visit or a referral from your own doctor.
How long does it take to get Vitamin K1 results?
Most Vitamin K1 results are available in 1–3 business days after your specimen arrives at the lab. You'll get an email the moment your results are ready, with everything viewable in your TestWell portal.
How much does a Vitamin K1 test cost?
Our Vitamin K starts at $36.99. That's the all-in price — no copays, no insurance hoops, no surprise bills. HSA and FSA cards are accepted.
Do I need to fast before my Vitamin K1 test?
Fasting is not required for the Vitamin K1 test. You can have your blood drawn any time of day.
Which lab will process my Vitamin K1 test?
Your test will be processed by Quest Diagnostics, Labcorp, or BioReference depending on which is closest to you and which lab carries the test. All three are CLIA-certified and trusted by hospitals nationwide. You'll choose your lab during checkout from 4,000+ locations.
Ready to test your vitamin k1?
Order in two minutes, get physician-approved, and visit a lab the same day. Starts at $36.99.