Correlation between total and ionic magnesium concentration in human serum samples is independent of ethnicity or diabetic state.

The relationship between total and ionic serum magnesium in health and chronic disease across different ethnicities has not been well studied. Accordingly, we have examined the interrelationship between total magnesium and ionic magnesium, as well as ionic calcium to ionic magnesium ratio, in 286 patients made up of indigenous and non-indigenous Australians, with or without diabetes. Significant correlations were noted between total and ionic magnesium in all groups (p < 0.001). Amongst people with diabetes, the correlation coefficient (r) was 0.81 whereas in non-diabetics, the r was 0.66. This relationship was independent of whether the sample was from indigenous (r = 0.71) or non-indigenous (r = 0.81) participants. Overall the correlation between total and ionic magnesium across all participants was 0.75. There was no correlation between serum total magnesium and serum ionic calcium (r = 0.07), and similarly none between serum ionic magnesium and serum ionic calcium (r = 0.26). There was, however, a significant negative correlation between the calcium: magnesium ratio and serum total magnesium (r = 0.80; p < 0.001) across all participants, irrespective of whether the sample was made up of indigenous (r = 0.83) or non-indigenous participants (r = 0.77), or of diabetics (r = 0.71) versus non-diabetics (r = 0.83). We conclude that total and ionic magnesium serum concentrations are strongly correlated, and that either gives an accurate assessment of magnesium status in health and chronic diabetes, irrespective of ethnicity.