Vitamins & Nutrients Updated Apr 17, 2026

Vitamin B2 (Riboflavin) (B2)

Vitamin B2 (Riboflavin) (B2) is a nutrient-related lab value that reflects riboflavin status in blood or a related specimen. It is used to summarize how much B2 is present and how that result compares with the Vitamin B2 (Riboflavin) normal range on a lab report or blood test. In the Vitamins & Nutrients panel, the B2 test helps organize nutrition-related data alongside other measured markers.

What Is Vitamin B2 (Riboflavin) (B2)?

Vitamin B2 (Riboflavin) (B2) is a lab value that reflects riboflavin, a water-soluble vitamin measured in a blood test or related specimen. On a lab report, B2 describes the amount of this vitamin present at the time of testing. It does not measure red blood cells directly, but it can be reviewed as part of a broader nutrient profile on a Vitamin B2 (Riboflavin) on a lab report.

Why Is Vitamin B2 (Riboflavin) (B2) Tested?

The B2 test is commonly included in a Vitamins & Nutrients panel and sometimes appears in broader nutrition-focused lab panels. It helps summarize riboflavin status along with other nutrient values when a clinician or lab is organizing biochemical data. A Vitamin B2 (Riboflavin) test may be ordered with other vitamin measurements to build a fuller picture of dietary intake and blood nutrient balance. In this context, B2 on a blood test is used as a reference marker rather than a stand-alone result.

Already have your Vitamin B2 (Riboflavin) results?

Upload your blood test to BloodSight and see what each result means in context.

Get Started

Vitamin B2 (Riboflavin) (B2) Normal Range

Group Range Unit
Adult Male 5–50 nmol/L
Adult Female 5–50 nmol/L

Reference ranges may vary by laboratory and individual factors.

What Does High B2 Mean?

A high B2 result generally means more riboflavin is present than expected in the measured sample. For Vitamin B2 (Riboflavin) on a blood test, values above the lab’s upper limit are often labeled high B2, and the exact cutoff depends on the method used. A Vitamin B2 (Riboflavin) test result above the reference interval usually reflects higher circulating vitamin content, often from recent intake or concentrated sample fluid. This is different from markers like RBC, Hct, or MCV, which describe red cell size or concentration.

Associated factors

Recent vitamin intake — a recent supplement or fortified food intake can increase circulating B2 and push the result into high B2.
Concentrated sample fluid — lower plasma volume can make the measured B2 appear higher because the vitamin is less diluted.
Timing after a meal — a sample drawn soon after B2 intake can show a temporary rise in measured concentration.
Supplement use — regular B2-containing supplements can produce a persistently high B2 test result compared with people not taking supplements.
Fortified foods — frequent intake of fortified drinks or cereals can raise riboflavin levels in blood.
Pregnancy-related shifts — changes in plasma volume and nutrient handling can alter a B2 result during pregnancy.
Physical training — heavy exercise can temporarily change fluid balance and make high B2 more likely on a blood test.
Smoking status — smoking can shift nutrient turnover and change where a B2 result falls within the reference range.
Lab method differences — different assays may report slightly different B2 values, making one result look high B2 in one lab and normal in another.

What Does Low B2 Mean?

A low B2 result generally means less riboflavin is present than expected in the tested sample. On a Vitamin B2 (Riboflavin) reference range, values below the lower limit are typically reported as low B2. A low Vitamin B2 (Riboflavin) test result can reflect reduced intake, reduced absorption, or greater loss before the sample is measured. It is often reviewed alongside RBC, Hct, and MCV when a broader nutrient pattern is being described.

Associated factors

Low dietary intake — limited intake of riboflavin-containing foods can lead to low B2 on a blood test.
Reduced absorption — if the body absorbs less riboflavin from the intestine, the measured B2 can fall.
Increased turnover — faster use of riboflavin for energy-related processes can lower the circulating level.
Poor storage — because B2 is water-soluble, the body does not store large amounts for long periods.
Frequent losses — repeated loss of nutrient-rich body fluid can reduce the measured B2 level.
Certain medications — some medicines can change riboflavin handling and make low B2 more likely.
Heavy alcohol use — alcohol can interfere with nutrient intake and metabolism, lowering B2 values.
High physical demand — prolonged exercise can increase nutrient use and move a result below the normal Vitamin B2 (Riboflavin) normal range.
Lab collection factors — delayed processing or sample handling differences can affect a Vitamin B2 (Riboflavin) test result.

How Vitamin B2 (Riboflavin) (B2) Relates to Other Values

B2 is often viewed with other values in the Vitamins & Nutrients panel, but it is not the same as RBC, Hct, or MCV. RBC and Hct describe how many red blood cells are present and how concentrated they are, while MCV describes average red cell size. When B2 is reviewed next to ferritin, folate, or vitamin B12, the pattern helps describe nutrient balance rather than one isolated number. A Vitamin B2 (Riboflavin) on a lab report is therefore best read as one piece of a larger biochemical profile.

What Factors Affect Vitamin B2 (Riboflavin) (B2) Levels?

Age, sex, and body size can shift where B2 falls within the normal Vitamin B2 (Riboflavin) normal range. Hydration status can change concentration, so a more concentrated sample may show high B2 and a more diluted sample may show low B2. Time of day, recent food intake, and recent exercise can also move the B2 test result slightly. Different laboratories may use different methods, so the same Vitamin B2 (Riboflavin) on a blood test can vary by assay. Diet patterns, supplement use, and pregnancy-related fluid changes are also common influences on B2 values.

How It Is Tested

A B2 test is usually done on a blood draw, and the lab measures riboflavin or a related riboflavin marker in the specimen. Results are commonly reported in ng/mL, µg/L, or nmol/L depending on the assay and lab. A Vitamin B2 (Riboflavin) test result should always be read with the units shown on the report.

How to Prepare

No fasting is usually required for a Vitamin B2 (Riboflavin) test as part of a routine vitamins panel. Because recent intake can affect B2, the timing of supplements or fortified foods may matter for interpretation.

Frequently Asked Questions

What is a normal B2 level?
A normal B2 level depends on the lab method, but many references use a range around 5 to 50 nmol/L. The Vitamin B2 (Riboflavin) normal range on a lab report should always be matched to the units shown by that lab. A Vitamin B2 (Riboflavin) test result inside the reference interval is usually reported as normal B2.
What does B2 stand for?
B2 stands for vitamin B2, also called riboflavin. On a B2 test, the result reflects riboflavin measured in blood or another specimen. The abbreviation B2 is the short label often used on a lab report.
What does a high Vitamin B2 (Riboflavin) mean on a lab report?
A high Vitamin B2 (Riboflavin) result means the measured riboflavin level is above the lab’s upper reference limit. This often reflects recent supplement use, fortified foods, or a more concentrated sample. In other words, high B2 usually describes more vitamin in the sample rather than a red cell change.
What does a low Vitamin B2 (Riboflavin) mean on a lab report?
A low Vitamin B2 (Riboflavin) result means the measured riboflavin level is below the lab’s reference interval. It can reflect lower intake, reduced absorption, or other factors that lower circulating B2. A low B2 result is interpreted in the context of the full vitamins panel and the test method.
Can hydration affect Vitamin B2 (Riboflavin)?
Yes, hydration can affect B2 because fluid volume changes concentration. A more concentrated blood sample can look like high B2, while a more diluted sample can look like low B2. This is one reason a Vitamin B2 (Riboflavin) test result is read with the lab’s reference range and collection details.
What is the difference between Vitamin B2 (Riboflavin) and MCV?
Vitamin B2 (Riboflavin) measures riboflavin status, while MCV measures average red blood cell size. They are different lab values and belong to different parts of a blood report. B2 is a nutrient marker, while MCV is a cell-structure marker.
What unit is Vitamin B2 (Riboflavin) measured in?
Vitamin B2 (Riboflavin) can be reported in nmol/L, ng/mL, or µg/L depending on the laboratory method. The unit should always be checked on the blood test result before comparing it to the normal range. Different units can make the same B2 value look numerically different.
How much can Vitamin B2 (Riboflavin) change between tests?
B2 can change modestly between tests because of recent diet, supplement use, hydration, and lab method differences. Small shifts are common, especially if the samples were drawn under different conditions. Larger changes can happen when intake or fluid balance changes more noticeably.
Is Vitamin B2 (Riboflavin) different for men and women?
For many labs, the Vitamin B2 (Riboflavin) reference range is the same for adult men and women. Some laboratories may still use method-specific ranges or different flagging rules. The B2 result should be interpreted using the reference range printed on the report.
Why is Vitamin B2 (Riboflavin) tested in a Vitamins & Nutrients panel?
B2 is tested in a Vitamins & Nutrients panel to summarize riboflavin status alongside other nutrient markers. This helps create a broader picture of nutrient balance on one lab report. It is a convenient way to group several vitamin-related values in one B2 test.
What does B2 on a blood test mean?
B2 on a blood test means the measured riboflavin value reported by the lab. It is a shorthand label for Vitamin B2 (Riboflavin) and is usually interpreted against the lab’s normal Vitamin B2 (Riboflavin) normal range. The exact meaning depends on the specimen type and units.
What does B2 mean on a lab report?
B2 on a lab report is the abbreviation for vitamin B2, riboflavin. It identifies the nutrient measurement rather than a red blood cell value. When the report shows high B2 or low B2, it is referring to that measured riboflavin level.

Disclaimer

This content is for informational and educational purposes only. It is not intended as medical advice, diagnosis, or treatment recommendation. Reference ranges may vary by laboratory. Always discuss your results with a qualified healthcare professional.

Related Tests

Vitamin D 25-OH D

Vitamin D (25-OH D) is the main blood marker used to show circulating vitamin D status. It reflects the amount of 25-hydroxyvitamin D in the blood, which comes from diet, supplements, and sunlight-related production. On a Vitamin D blood test or Vitamin D on a lab report, this value is often reviewed to compare with the Vitamin D reference range and other nutrient markers.

→
Vitamin B12

Vitamin B12 is a lab value that shows the amount of vitamin B12 measured in a blood sample. On a lab report or blood test, it helps describe nutritional status and how the result compares with the Vitamin B12 reference range. High Vitamin B12 and low Vitamin B12 can both reflect changes in intake, absorption, or sample-related factors.

→
Folate

Folate is a lab value that reports the amount of Folate measured in a blood sample. Folate on a blood test is used in vitamins and nutrients panels to show how that nutrient level compares with the Folate reference range. It is often read with red cell markers such as RBC, Hct, and MCV to provide a fuller picture of blood composition.

→
Zinc Zn

Zinc (Zn) is a trace mineral measured on some blood tests to show the amount of Zn in circulation. On a lab report, it is usually reviewed as part of a Vitamins & Nutrients panel, where it helps describe overall nutrient balance and possible variation in intake, absorption, or loss.

→
Selenium Se

Selenium (Se) is a trace element measured in blood that helps describe nutrient status and how much selenium is circulating at the time of the test. Selenium on a lab report or selenium on a blood test is usually interpreted with the Selenium reference range, the testing method, and related vitamins and minerals.

→
Vitamin B6

Vitamin B6 is a vitamins and nutrients lab value that reflects the amount of Vitamin B6 measured in blood. On a blood test, it is often reviewed as part of the Vitamins & Nutrients panel to compare the result with the Vitamin B6 reference range. High Vitamin B6 or low Vitamin B6 can reflect differences in intake, supplement use, hydration, or lab method.

→