Soledad Vera, Luz Maria Pozo, René Lopez, Joaquin Diaz and Paulette Conget
Background: The broadly disseminated notion that plasmatic concentration of magnesium is not a good indicator of its corporal status bases on the fact that normal magnesemia is reported in people with magnesium deficiency. The aim of this study was to identify a suitable sample for the assessment of magnesium corporal status in magnesium moderate deficiency.
Methods and Findings: Female mice were fed with regular or low magnesium diet for 45 days. Bone, muscle, platelets and plasma were sampled and magnesium content was determined by atomic absorption spectrophotometry or using a colorimetric assay. As expected, magnesium content in bones was significantly diminished in animals fed with low magnesium diet when compared with those fed with normal diet (14.6 ± 0.5 versus 16.7 ± 0.2 mmol/100 g, p<0.05). Magnesium moderate deficiency was replicated in plasma (0.76 ± 0.08 versus 0.94 ± 0.09 mmol/L, p<0.05) but not in muscle or platelet samples. The correlation between bone and plasma magnesium contents was 0.53. ROC curve analysis revealed 83% specificity and 75% sensitivity for plasma magnesium cut off of 0.84 mmol/L.
Conclusion: Plasma is a suitable sample to determine magnesium corporal status when deficiency is moderate. But, poor accuracy of colorimetric technique limits its use.
