Vitamins, minerals and amino acids
Magnesium intracellulair
Magnesium in the red blood cells; sometimes used as a measure of the body's store, but without fixed cutoff values.
Everything about this testWhat it measures
This analysis measures the amount of magnesium in the red blood cells (erythrocytes), not in the fluid around the cells. The idea behind it is that the value in cells better reflects the store in the body, because only about 1 percent of the magnesium is in the blood fluid and the rest is in bones and cells. Whether this is also true in practice has not been well shown. In the Netherlands, only a few laboratories perform the test, each with its own method and its own reference values.
- A possible magnesium deficiency in the cells, as an addition to serum magnesium; the clinical meaning has not been established
High
As far as is known, a raised value has no separate clinical meaning. It can fit the use of magnesium supplements, but also differences in measurement method or in how the sample was processed. With reduced kidney function, magnesium in the body can rise; serum magnesium is then the usual measurement. Without kidney disease or symptoms, a slightly raised value usually does not point to a problem.
Low
A low value can fit a magnesium deficiency, such as with prolonged diarrhea, a lot of alcohol, bowel diseases or use of water pills (diuretics) or stomach acid inhibitors. However, there is no agreed cutoff below which there is a deficiency, and it has not been studied whether people with only a low value in the red blood cells benefit from extra magnesium. Symptoms such as tiredness and muscle cramps usually have another cause; according to Thuisarts, magnesium does not help against nighttime calf cramps, except sometimes during pregnancy. A low value says little without serum magnesium, potassium, calcium and kidney function alongside it.
If your result is abnormal
With an abnormal result, the GP usually has serum magnesium, potassium, calcium and kidney function measured and checks whether there is a reason for loss, such as medicines, alcohol or bowel symptoms.
Reliability
There are no fixed cutoff values and the measurement has been studied less well than serum magnesium (magnesium in the blood fluid). Measurement methods and reference values are not aligned nationally; each laboratory uses its own limits. It has not been shown that this measurement is better than serum magnesium at showing who has a deficiency or who benefits from treatment. An abnormal result is therefore harder to interpret.
Limitations
- Laboratories use different methods and reference values; results are therefore poorly comparable.
- How the sample is processed (time until cells and fluid are separated, hemolysis) affects the result.
- Recent use of magnesium supplements can affect the value.
How common is this
How often a low intracellular magnesium occurs is not known; there are no Dutch figures and no agreed cutoff values. According to the Netherlands Nutrition Centre (Voedingscentrum), a magnesium deficiency does not occur easily, because magnesium is found in many foods.
Who is this useful for
When a magnesium deficiency is suspected, for example with prolonged diarrhea, heavy alcohol use or long-term use of water pills (diuretics) or stomach acid inhibitors, serum magnesium says more, because that measurement has been studied better and has fixed cutoff values. This analysis can be an addition to it, knowing that it is not established what an abnormal result means.
Downsides and risks
- Because there are no agreed cutoff values and the meaning of an abnormal result is not established, an abnormal result can cause unnecessary worry, unnecessary follow-up testing or unnecessary supplement use.
- A low result is easily seen as the explanation for vague symptoms such as tiredness, so that another cause is found later.
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