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Background: Hypomagnesemia is often caused by renal magnesium wasting. Intracellular magnesium is the main component of magnesium in blood. In clinical observations you get the impression that serum magnesium values do not always correlate with the symptoms of hypomagnesemia. However, usually serum level only and not intracellular magnesium is checked during the treatment of patients.
Questions: Is there a direct correlation between intracellular and serum magnesium? Is there any correlation between magnesium values (intracellular and serum) and the symptoms of hypomagnesemia? Are there any differences in the intraerythrocytic magnesium concentration between patients with hereditary renal magnesium wasting and patients with Cyclosporin A associated magnesium wasting?
Design: Healthy probands without any problems in magnesium homeostasis (n = 26), patients with hereditary salt losing disorders with renal magnesium wasting (n = 7 GS/cBS), patients with hereditary salt losing disorders without renal magnesium wasting (n = 12, 6 x ROMK, 6 x NKCC2) and patients with Cyclosporin A associated magnesium wasting (n = 18) take part in the study. The values for intraerythrocytic and serum magnesium were measured from each participant taking part in the study. Additionally they were asked for the symptoms of hypomagnesemia by a questionnaire.
Results: In healthy probands there is a correlation between the values of serum magnesium and intraerythrocytic magnesium (r = 0,5). Nevertheless it remains unproven, if the correlation has the form of saturation or has a linear outline. The study shows that the saturation and the linear correlation are very similar to each other. Patients with GS/cBS have lower intraerythrocytic and serum magnesium values than patients of any other group (p < 0,05). Cyclosporin A associated magnesium wasting leads to lower serum magnesium, but there is no influence on the intraerythrocytic values. Healthy probands and patients with aBS have no abnormalities in magnesium homeostasis. The worst clinical symptoms of hypomagnesemia have patients with GS/cBS. Both patients with aBS and Cyclosporin A associated magnesium wasting have symptoms of hypomagnesemia, but not as much as patients with GS/cBS.
Conclusion: Intraerythrocytic magnesium values correlate with extracellular magnesium concentration. The form of the correlation could not be defined. Hereditary renal magnesium wasting leads to lower intraerythrocytic and serum magnesium values. Cyclosporin A associated magnesium wasting does not lead to an intracellular magnesium deficiency, but to lower values in serum. Patients with intracellular and serum magnesium deficiency have the worst and most frequently symptoms of hypomagnesemia.