Serum magnesium concentration a need for revision especially in renal failure

Abstract

Dear Editor, Plasma magnesium concentration is kept within narrow limits. In states of negative magnesium balance, initial losses come from the extracellular space while equilibrium with bone stores does not begin for several weeks. Normal plasma magnesium concentration based on literature is 1.7–2.1 mg/dL (0.7–0.9 mmol, or 1.4–1.8 mEq/L).[1] Half of the total body magnesium is present in soft tissue and another half in bone and 1% is present in the blood. Assessment of total magnesium store is impossible at now and serum magnesium level evaluation cannot show total serum status, magnesium ion measurement has been done in selected centers without approved more beneficial yields. Magnesium has a long biological half‐life after oral supplementation and equilibrates slowly in most tissue including serum. It has been shown that at cut‐off levels of 1.94 mg/dL and 2.19 mg/dL clinical magnesium deficiency occurred in 10% and 1%, respectively. It was shown that serum magnesium concentration (SMC) lower than 2.1 mg/dL increases the risk of Diabetes mellitus type 2 and levels of 0.85 mmol/L or 2.1 mg/dL can be considered as an reasonable lower limit of SMC.[2] Importance of new definition for hypomagnesemia has been more prominent in special conditions because of hypomagnesemia increase mortality in septic and critically ill patients by mechanisms such as increased need for mechanical ventilation and longer duration of ventilation support, irreversible renal dysfunction. in a study magnesium level of 1.5 mg/dL versus 2 mg/dL increases the risk of bacterial infection.[3] In end‐stage renal disease magnesium level below 1.94 mg/dL increase death risk of coronary heart disease up to 33% make that authors were debated about validity of SMC in an accepted reference of 1.7–2.67 mg/dL as a confidential clinical useful reference in clinical affairs; for example the role of magnesium as a protective against vascular calcification in chronic kidney disease is well known and serum magnesium lower than 1.94 mg/dL has been approved that can be associated with increased mortality that obligate clinician to change lower cut off level of SMC as low as 0.8 mmol/L (1.94 mg/dL) but it may not be enough because in patients under hemodialysis after 3 years followed up was shown that serum magnesium under 2.77 mg/dL was associated with higher mortality compared to higher 2.77 mg/dL.[4] Other study goes beyond and shows serum magnesium over 3 mg/dL can decrease soft tissue calcification[5] it can explain why in patients under maintenace hemodialysis normal serum magnesium levels was associated with higher cardiovascular mortality compared to patients with hypermagnesemia.[6]