ERYTHROCYTE MAGNESIUM IN ELDERLY PATIENTS - NOT A RELIABLE GUIDE TO MAGNESIUM STATUS

To assess body magnesium status in various illness states in older peo ple by measurement of serum magnesium (S Mg and erythrocyte magnesium (E Mg) and to explore the limitations of E Mg measurement. S Mg and E Mg were measured in 150 consecutive out-patients, mean age 77 years, a nd in 100 consecutive in-patient admissions, mean age XO years. Result s were analysed for different diagnostic groups S Mg was normally dist ributed for both in-patients and out-patients, mean values 0.79 mmol/l and 0.77 mmol/l respectively. In-patient E Mg concentrations were oft en higher but the distribution was considerably skewed, median 2.28 mm ol/l, mean 2.35 mmol/l. Out-patient E Mg concentration followed a near normal distribution, median 2.32. mmol/l, mean 2.30 mmol/l. There was a significant correlation between E Mg and S Mg for out-patients, R = 0.29 (p < 0.001). In-patients with infections and pressure sores had significantly raised E Mg concentrations but normal or low S Mg. High E Mg concentrations in illness are likely to be due to alterations in characteristics of the erythrocytes themselves rather than an indicati on of body magnesium excess. E Mg concentrations in illness should be interpreted with caution.