A Proposed Scale to Assess Magnesium Status Using Serum Calcium and Magnesium Ratios

Background/Objectives: Reliable markers of human magnesium (Mg) status are needed. Methods: Current Mg studies report ratios between serum Mg and calcium (Ca) using four interchangeable expressions (i.e., molar or weight calculations of Mg/Ca or Ca/Mg). We propose a scale using ratios of serum Mg and Ca to assess Mg status, unified for all four expressions. We explore its application for case studies and published research. Results:Case Studies (4)-the proposed serum Mg/Ca scale showed better Mg diagnostic value than serum Mg alone. Published Studies-A. The proposed Mg/Ca scale's "depleted Mg" status predicted mortality among hospitalized COVID-19 patients in ROC/AUC analyses. B. The serum Ca/Mg proposed scale, when applied to "healthy" adults with "normal" serum Mg, exposed a "seriously depleted" to "adequate" range of Mg status. C. In a study of periodontal disease, patients designated "adequate" or "mild" Mg depletion by the proposed scale showed greater 5-year improvement than those with scale's "moderate to serious" Mg depletion status. D. Finally, the proposed scale demonstrated appropriate diagnostic value of serum Ca/Mg in acute coronary syndrome patients only when "corrected Ca" was NOT used in ratio calculation. Conclusions: The proposed scale needs both total serum Ca and Mg measures in identical units, i.e., mg/dL or mg% (for weight ratios); mmol/L or mEq/L (for molar ratios). Authors/reviewers/editors need to take care when reporting units/methodology of serum Mg and Ca ratios for clear reporting as to weight or molar ratio and use of total or corrected values. Future trials and statistical testing are needed to determine whether ratios between serum Mg and Ca yield more precise measures of physiological Mg status than serum Mg alone. Our findings indicate the proposed scale is worthy of further study as a marker of Mg deficit.