Vitamin B2 (Riboflavin) levels: what's normal, high and low
A B vitamin needed for energy production and red blood cell formation.
Medically reviewed by Youmna DiStefano, MD · Last reviewed September 2026
The short answer
Vitamin B2 (Riboflavin) is measured with a standard blood draw; no fasting is needed. A typical reference range is 137 – 370 nmol/L. At TestWell it's $66.99 all-in as Vitamin B2 (Riboflavin), results in 3–5 business days, drawn at Quest. An out-of-range result is a prompt to look closer, not a diagnosis.
- Units
- nmol/L
- Sample
- Blood draw
- Fasting
- Not required
- Results
- 3–5 business days
- Price
- $66.99
- Labs
- Quest
Vitamin B2 (Riboflavin) 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+ | 137 – 370 nmol/L |
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 B2 (Riboflavin) result may mean
Can reflect inadequate dietary intake or malabsorption.
What a low Vitamin B2 (Riboflavin) 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 B2 (Riboflavin) mean?
Low riboflavin (vitamin B2) is uncommon in the US and points to a diet low in dairy, eggs, meat and fortified grains — strict vegan or very restricted eating — or to alcohol use, malabsorption, hypothyroidism, or medications that interfere with it (some antidepressants, phenothiazines, long-term barbiturates). It rarely occurs alone; other B vitamins are usually low too.
Common causes of a low Vitamin B2 (Riboflavin)
- Low intake: vegan or restricted diets without fortified foods
- Alcohol use disorder, malabsorption, eating disorders
- Hypothyroidism, adrenal insufficiency
- Medications: tricyclics, phenothiazines, phenobarbital, probenecid
- Phototherapy in newborns
Ordered from most to least common.
Symptoms that can go with it
- Cracks at the corners of the mouth, sore red tongue, sore throat
- Scaly rash around the nose and mouth, eye irritation and light sensitivity
- Anemia, fatigue
What clinicians usually check next
- B1, B6, B12 and folate — deficiencies cluster
- TSH, dietary review
- Riboflavin is inexpensive and safe to replete under clinician guidance; retest in 8–12 weeks
Follow-up tests at TestWell: TSH (Thyroid Stimulating Hormone) ($26.99), TSH + Free T4 ($27.99), Folate (Vitamin B9) ($32.99).
Can riboflavin help migraines?
High-dose riboflavin (400 mg/day) has evidence for migraine prevention in some trials; it is a separate use from correcting a deficiency and is a conversation for a clinician.
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 B2 (Riboflavin) test?
Order online, a licensed physician reviews the requisition, and you walk into a nearby lab for the draw. Vitamin B2 (Riboflavin) is available on its own or inside these panels — panels cost less per marker when you want the fuller picture.
| Option | Includes | Price |
|---|---|---|
| Vitamin B2 (Riboflavin) | This marker only | $66.99 |
Quest vs. Labcorp for Vitamin B2 (Riboflavin): 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 | $66.99 |
| Labcorp | No | — |
| 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 B2 (Riboflavin).
Frequently asked
What does a low Vitamin B2 (Riboflavin) mean?
Low riboflavin (vitamin B2) is uncommon in the US and points to a diet low in dairy, eggs, meat and fortified grains — strict vegan or very restricted eating — or to alcohol use, malabsorption, hypothyroidism, or medications that interfere with it (some antidepressants, phenothiazines, long-term barbiturates). It rarely occurs alone; other B vitamins are usually low too.
Can riboflavin help migraines?
High-dose riboflavin (400 mg/day) has evidence for migraine prevention in some trials; it is a separate use from correcting a deficiency and is a conversation for a clinician.
Do I need a doctor's order to test my vitamin b2 (riboflavin)?
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 B2 (Riboflavin) results?
Most Vitamin B2 (Riboflavin) 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 B2 (Riboflavin) test cost?
Our Vitamin B2 (Riboflavin) starts at $66.99. 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 B2 (Riboflavin) test?
Fasting is not required for the Vitamin B2 (Riboflavin) test. You can have your blood drawn any time of day.
Which lab will process my Vitamin B2 (Riboflavin) 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 b2 (riboflavin)?
Order in two minutes, get physician-approved, and visit a lab the same day. Starts at $66.99.