Magnesium test - red cell

From DoctorMyhill
Jump to: navigation, search
Test Details for Ordering
Test Magnesium test - red cell
Laboratory Biolab Medical Unit
Price £37.00
Sample required blood
To order this test, please, go to Ordering Tests.

Please, make sure you have read When not to use this website to ascertain whether having this test is an appropriate and safe course of action for you.


This test measures the amount of the mineral magnesium inside the red blood cells. This is the test I do most often, partly because I see many patients with fatigue, partly because it is a very common deficiency and partly because it is a very difficult mineral to correct.

Most doctors do not understand the difference between a serum magnesium and a red cell magnesium. Serum levels must be kept within a tight range, or the heart stops. Therefore serum levels are maintained at the expense of levels inside cells. Most labs just do serum levels and patients are told their magnesium is normal.

So we have to measure intracellular magnesium. The easiest cell to get at is the red cell, hence this test.

For advice on treating magnesium problems please see Magnesium.


This test is performed on a blood sample.


The kit for this test includes a lithium heparin green top blood tube, packaging materials for transporting the blood sample in the post, a request form and a pre-paid envelope.


To complete the test: have the blood taken and put in the blood tube (see blood letting information), make sure that your name and date of birth are clearly marked on the tube. Check that your details are correct on the request form. Using the packaging material provided prepare the sample for posting in the enclosed envelope. Please, make sure that the request form is sent along with the samples. Do not post the sample on a Friday.

Please, note that there is an interpretation fee for my letter to your GP. See Ordering Tests for more details.