Explanation

Vitamin A: what is measured?

Vitamin A is needed for seeing in the dark, growth, healthy skin and mucous membranes, and the immune system. It is found as retinol in liver, fish, butter and egg yolk, and in the Netherlands it is added to margarine, low-fat spreads and cooking and frying products; the body also makes it from beta-carotene in vegetables and fruit. Vitamin A dissolves in fat, is absorbed in the gut together with fat and is stored mainly in the liver. The test measures retinol in the blood.

What can it detect?

Vitamin A deficiency due to poor fat absorption, for example with a disease of the pancreas, liver or intestine or after bariatric surgery
Too much vitamin A from supplements or a lot of liver, which can be harmful especially during pregnancy

Result

What does the result mean?

Vitamin A too high

A raised vitamin A is usually due to supplements containing vitamin A or to a lot of liver and liver products; beta-carotene from vegetables and fruit does not cause poisoning. Too much vitamin A over a long period can cause symptoms such as headache, nausea, tiredness, dizziness, hair loss and dry skin and mucous membranes. During pregnancy, too much vitamin A can harm the unborn child; the safe level is then 3000 micrograms per day. A slightly raised value can also occur with reduced kidney function, without too high an intake.

Vitamin A too low

A low vitamin A may fit a deficiency. In the Netherlands a deficiency is rare; it occurs mainly with poor fat absorption (diseases of the pancreas, liver or intestine, after bariatric surgery), with excessive alcohol use and with an eating disorder. The first sign of a long-term deficiency is night blindness; in addition, dry, flaky skin, dull hair and reduced resistance to infection can develop. During an infection or inflammation, the value can fall temporarily without the store in the liver being used up.

After an abnormal result

With a low value, the GP looks for a cause of poor absorption, such as a disease of the liver, pancreas or intestine, and consults an internist (specialist in internal medicine) or gastroenterologist if needed. With a raised value, the GP asks about supplements and liver products and usually advises stopping them.

Reliability

How reliable is the test?

A clearly low or strongly raised value is easy to interpret, but the value in the blood stays normal for a long time because the liver has a large store; a slightly abnormal value therefore says little about the store. In people without symptoms or risk factors, a deficiency is rare. The test is mainly used in conditions with poor fat absorption and when too high an intake is suspected.

What can affect the result?

An infection or inflammation can temporarily lower the value.
A liver disease can lower the value and reduced kidney function can raise it, regardless of intake.
Vitamin A is sensitive to light; the sample must be kept in the dark.
Reference values differ between laboratories.

Who it is for

Who is the test useful for?

Useful for

Useful in conditions with poor fat absorption, such as diseases of the pancreas, liver or intestine, after bariatric surgery, with severe malnutrition or an eating disorder, and with symptoms such as night blindness. Also useful when too high an intake from supplements is suspected. When planning a pregnancy or during pregnancy, measuring is usually not needed: the dietary advice then is to eat no liver, limit liver products and use no supplements containing vitamin A. In healthy people without symptoms, a slightly abnormal result says little.

How common is it?

A vitamin A deficiency is rare in the Netherlands. According to the Netherlands Nutrition Centre (Voedingscentrum), a large share of Dutch people take in less vitamin A than recommended, but this does not seem to cause symptoms in the general population. Worldwide, a deficiency is an important cause of blindness in children, mainly in developing countries.

The Netherlands Nutrition Centre (Voedingscentrum) and the NVKC

Drawbacks and risks

A slightly low value during or shortly after an infection can wrongly be seen as a deficiency.
Taking supplements containing vitamin A on your own initiative after a low result can lead to too much vitamin A, which is harmful especially with a (possible) pregnancy.

Get tested

Vitamin A: test panels

Vitamin A is part of these test panels. You order online and have your blood drawn at a collection point or collect the sample at home.

Blood draw
Vitamin A
Vitamin A; vision, skin, and immunity.
€ 41,00
Fingerstick
Vitamin A
Vitamin A; vision, skin, and resistance.
€ 41,00

Evidence

Sources

This explanation is based on Dutch guidelines and independent information. It is general information, not a diagnosis. Discuss an abnormal result with your GP.

More about risks and results

More explanations

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