Magnesium-based interventions for normal kidney function and chronic kidney disease.

Magnesium (Mg) is one of the most important cations in the body, playing an essential role in biological systems as co-factor for more than 300 essential enzymatic reactions. In the general population, low levels of Mg are associated with a high risk of cardio-vascular disease (CVD). Despite the accumulating literature data, the effect of Mg administration on mortality in chronic kidney disease (CKD) patients has never been investigated as a primary end-point. We conducted a systematic search of studies assessing the benefits and harms of Mg in CKD (stages 1 to 5 and 5D), and considered all randomized controlled trials (RCTs) and quasi-RCTs evaluating Mg-based interventions in CKD. As a phosphate binder, Mg salts offer a plausible opportunity for doubly favorable effects via reduction of intestinal phosphate absorption and addition of potentially beneficial effects via increasing circulating Mg levels. Mg supplementation might have a favorable effect on vascular calcification, although evidence for this is very slight. Although longitudinal data describe an association between low serum Mg levels and increased total and cardiovascular mortality, in patients with CKD, the existing RCTs reporting the effect of Mg supplementation on mortality failed to demonstrate any favorable effect. As with many other variables that influence hard end-points in nephrology, the role of Mg in CKD patients needs to be investigated in more depth. Additional research that is well-designed and directly targeting the role of Mg is needed as a consequence of limited existing evidence.