Serum magnesium concentration

Method

Magnesium concentration in serum, plasma, or whole blood by clinical colorimetric assay (calmagite or xylidyl blue) or by atomic absorption spectrometry. Matrix and assay recorded on the edge — erythrocyte and whole-blood magnesium sample a different pool from serum and the values are not interchangeable.

The method is part of the endpoint identity. Studies measuring the same quantity by a different method are held as separate endpoints.

Notes

Confused with dietary magnesium intake, which is milligrams per day from a food-frequency questionnaire or diet record. That is an exposure estimated from self-report; this is an assayed biochemical level. A review that analyses intake and status side by side is analysing two constructs, and only the assayed value belongs here. Also distinct from urinary magnesium excretion, which rises both with higher intake and with renal wasting and therefore carries no fixed direction of benefit.