The effect of dietary magnesium supplementation on the cellular abnormalities of erythrocytes in patients with beta thalassemia intermedia.

BACKGROUND AND OBJECTIVE Reduced serum or erythrocyte Mg have been reported in human beta thalassemia. These deficiencies may play a role in the cellular abnormalities characteristic of this disorder. We have therefore studied the effect of dietary Mg supplementation in patients with beta thalassemia intermedia in order to establish whether it improves the abnormalities of thalassemic erythrocytes. DESIGN AND METHODS Plasma and erythrocyte Mg were determined in 11 patients with b thalassemia intermedia, not requiring chronic transfusion therapy, and in 17 normal controls. Inclusion criteria included normal renal and liver function and performance status of 70% or greater. Seven patients were enrolled for the Mg supplementation study, after the appropriate informed consent was obtained. They were given a starting dose of 0.6 mEq/kg/day of magnesium pidolate, divided into two oral daily doses, for four weeks. In a 70-kg subject, a daily Mg dose of 42 mEq corresponds to 504 mg of Mg, with the daily Mg intake of normal subjects being 418 +/- 120 mg for males and 343 +/- 94 mg for females. After 28 days of treatment, five of the patients continued the protocol with a daily dosage increased to 1.2 mEq magnesium pidolate/kg/day, divided into two oral administrations, for an additional four weeks. RESULTS In patients with untransfused beta thalassemia intermedia we found reduced erythrocyte Mg (in mmol/kg Hb, 6.12 +/- 1.5, n = 11 vs. 8.69 +/- 0.89, n = 17, respectively, p < 0.0001) and normal serum Mg. In the seven patients given oral Mg supplements, at Mg dosages of 0.6 mEq/kg/day we observed significant increases in erythrocyte Mg, and significant improvement in some of the characteristic abnormalities of beta that erythrocytes (increased Na-K pump, KCl cotransport, cell dehydration, increased osmotic resistance). These changes were maintained in the 5 patients who were treated with 1.2 mEq of Mg/kg/day. Follow-up studies showed a return to baseline conditions. There were no signs of Mg toxicity, with the only side effect being diarrhea, which was generally mild, but led to discontinuation for one patient after the first four weeks. INTERPRETATION AND CONCLUSIONS These data indicate that dietary Mg supplementation improves some of the characteristic cellular function abnormalities of b thalassemia intermedia. The possible therapeutic value of this strategy should be further tested in these patients.