Vitamins, minerals and amino acids
Vitamine A
The amount of vitamin A (retinol) in the blood; with poor fat absorption or a suspicion of too much vitamin A.
Everything about this testWhat it measures
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.
- 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
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.
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.
If your result is abnormal
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
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.
Limitations
- 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.
How common is this
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.
Who is this 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.
Downsides 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.
Sources
Always discuss an abnormal result with your GP. If a result is strongly abnormal, we try to reach you as soon as possible. Read your result yourself as well and contact your GP if in doubt. A test does not make a diagnosis. Read more about risks and results