Vitamin B2 (riboflavin) test: what the result means

Riboflavin, also called vitamin B2, is a water-soluble vitamin that the body does not store — whatever is not used leaves in the urine, so it has to be taken in with food continuously. It takes part in many metabolic processes: it helps the body release energy from protein, fat and carbohydrate, and it supports healthy skin, eyesight and the working of the nervous system. The richest sources are milk, eggs, fortified breakfast cereals, mushrooms and plain yoghurt; it matters that these foods are kept away from direct sunlight, because ultraviolet light destroys riboflavin. The blood test is most often done together with the other B group vitamins (B1, B3, B6, B9, B12), when a shortage of them is suspected because of an inadequate diet or absorption problems. The result is assessed together with symptoms and other tests, because publicly available sources give no single universal blood reference range for riboflavin — it depends on the laboratory's method.

• When there are signs of tiredness, nerve problems (numbness, tingling) or skin changes that could be linked to a shortage of B group vitamins
• In coeliac disease, Crohn's disease or another disease of the digestive tract that interferes with the absorption of nutrients
• When alcohol has been used in larger amounts over a long time, or after operations on the digestive tract (for example gastric bypass)
• When taking certain medicines that can reduce the absorption of B vitamins or their amount in the body
• With certain genetic variants (for example changes in the MTHFR gene) linked to the metabolism of B vitamins
• When general B vitamin test results are unclear and the symptoms persist

Publicly available reliable sources (MedlinePlus, NHS) do not give a general, universal blood reference range for riboflavin — how the result is interpreted depends on the particular laboratory's method. You will find the exact range on your own result sheet, and the meaning is something to discuss with your doctor, who weighs it together with your symptoms and other tests.

How much riboflavin is needed and where it comes from

Per the NHS, adults need about 1.3 mg of riboflavin a day for men and 1.1 mg for women; the body does not store it, so a daily source with food is needed. The best sources are milk, eggs, fortified breakfast cereals, mushrooms and plain yoghurt, and these foods are better kept away from direct sunlight, because ultraviolet light destroys riboflavin.

Riboflavin is a water-soluble vitamin — the body does not store it and the excess leaves in the urine, so a high blood value is most often linked not to the vitamin itself but to other conditions. Per MedlinePlus, raised B group vitamin results can point to conditions such as liver disease. Always discuss what it means with your doctor, together with your other tests.

Causes listed for a raised result:

• Liver disease
• Some food supplements taken in larger amounts than needed
• Features of the laboratory method — how results are interpreted differs from laboratory to laboratory

What to discuss with a doctor:

• Liver function markers (ALT, AST) — they help to assess whether the change is connected with the liver
• A review of the food supplements being taken, together with your doctor
• When to repeat the test, if the first result is unclear

A low vitamin B2 result

A reduced amount of riboflavin most often points to not getting enough of it with food, or to an absorption problem. Per MedlinePlus, a B vitamin test is ordered when there is tiredness, nerve problems or skin changes, and also in diseases of the digestive tract or with alcohol use. Per the NHS, the body does not store riboflavin, so it needs to be taken in with food every day.

Causes listed for a low result:

• Not enough riboflavin in food — milk, eggs, fortified cereals, mushrooms and yoghurt are the main sources
• Diseases of the digestive tract that interfere with absorption — coeliac disease, Crohn's disease, malabsorption syndrome
• Long-term use of alcohol in larger amounts
• The state after operations on the digestive tract (for example gastric bypass)
• Certain medicines that reduce the absorption of B vitamins or their amount in the body

Symptoms listed for a shortage:

• Tiredness
• Nerve problems (numbness, tingling)
• Skin changes

What to discuss with a doctor:

• A review of eating habits, together with your doctor or a dietitian
• The possibility of a disease of the digestive tract (coeliac disease, Crohn's disease), if the symptoms persist
• Other B group vitamin tests (B1, B6, B9, B12), since shortages often appear together
• Whether an additional source of the vitamin is needed — that is for the doctor to decide

See also

Related pages: vitamin D test and tests for fatigue.