This is a single blood test for magnesium, measured in whole blood rather than serum, which can give a more complete picture of the body's total magnesium level. It suits people who want the whole blood method specifically, rather than the more common serum test.
1 biomarker as listed by Blue Horizon Medicals.
This test measures magnesium in whole blood rather than in serum, the more commonly tested sample type. Because most of the body's magnesium is held inside cells rather than in the fluid part of blood, a whole blood measurement can give a more complete picture of total magnesium levels than a serum test, which mainly reflects magnesium outside the cells. Low magnesium is commonly associated with fatigue, muscle weakness and cramps, and dietary deficiency is more common than often assumed.
Within the comparison group of magnesium tests we track, this is by far the most expensive, at £136.25 against a group median of £50.13, more than double the next cheapest option. Forth's home kit costs £45, and Blue Horizon's own serum-based Magnesium test costs £45.25, roughly a third of the price of this whole blood version. Medichecks' serum test is £55. The whole blood method is measured less often than serum magnesium, which may explain some of the price difference, but the gap here is large enough that it is the main reason for this test's low value for money score.
Documentation is thorough, with a detailed description and the sample type and collection options clearly stated. Collection is by venous blood draw at a clinic or nurse home visit only, with results in around ten days. Trust signals reflect Blue Horizon's Trustpilot rating and its UKAS ISO 15189 partner labs, and, as with its other tests, doctor review is an optional checkout extra rather than a default inclusion.
This test could suit you if a clinician has specifically recommended a whole blood magnesium measurement rather than the more commonly used serum test, since the two methods can give different readings. It requires a venous blood draw at a clinic or nurse visit, so you will need to be able to attend one or arrange a home visit.
For most people wanting a general magnesium check, Blue Horizon's own serum-based Magnesium test costs £45.25, around a third of the price of this whole blood version, and Forth and Medichecks offer similar serum tests from £45 to £55. Choose the whole blood version only if you specifically need that method rather than a standard serum reading.
This is a whole blood test for magnesium. You give a venous blood sample, either at a clinic or via a nurse home visit; there is no at-home collection option for this test. Once your sample reaches the laboratory, results are typically ready in around ten days. A doctor's review of your results can be added as an opt-in extra at checkout.
This whole blood magnesium test costs £136.25, well above the £50.13 median for comparable magnesium tests we track. Blue Horizon's own serum-based Magnesium test costs just £45.25, and Forth and Medichecks offer serum tests from £45 to £55. The whole blood method used here is measured less often, and may give a more complete picture of total magnesium than a serum reading, but the price gap is substantial.
The listing publishes a detailed description, the full biomarker list, a stated turnaround, clear collection options, the sample type; it does not state what the report looks like.
A single-marker test measuring exactly what it sets out to; depth is not the point of this comparison group.
A blood sample taken at home by a visiting nurse or phlebotomist; with a venous or clinic option as well; a home nurse visit is offered; results in around 10 days, slower than similar tests.
Results are reviewed by a doctor; the provider does not describe the report format.
Trustpilot 4.2 from 395 reviews; accredited lab (UKAS ISO 15189 partner labs); trading 17+ years.
£136.25 against a comparison-group median of £50.13 (+172%).
Calculated 13 September 2026 from the facts we hold about this test and provider, using our published scoring formula. Scores are not hand-edited.
This test belongs to our Magnesium test comparison group. See how it stacks up against equivalent tests from other providers.
Closely matches the cheapest magnesium test on the market
Checks serum magnesium levels, a mineral linked to fatigue, muscle cramps and weakness when low.
Pricier than two peers, cheaper than whole-blood option
Measures serum magnesium, a mineral involved in muscle function, nerve signalling and heart health. Suited to people with fatigue, cramps or low energy who want to check whether low magnesium could be a factor.
Cheapest single-marker magnesium test we compare
A single-marker blood test that measures your serum magnesium level, suited to anyone who wants to check this one mineral rather than a full panel.
Closely matches the cheapest magnesium test on the market
Checks serum magnesium levels, a mineral linked to fatigue, muscle cramps and weakness when low.
Pricier than two peers, cheaper than whole-blood option
Measures serum magnesium, a mineral involved in muscle function, nerve signalling and heart health. Suited to people with fatigue, cramps or low energy who want to check whether low magnesium could be a factor.
Cheapest single-marker magnesium test we compare
A single-marker blood test that measures your serum magnesium level, suited to anyone who wants to check this one mineral rather than a full panel.
