Serum ionized magnesium levels and ionized calcium-to-magnesium ratios in adult patients with sickle cell anemia

Low levels of total magnesium in sickle cell erythrocytes have been linked to increased sickling due to cell dehydration. We tested the null hypothesis that adult sickle cell anemia (SCA) patients have the :same serum level of ionized Mg (Mg2+) and Ca2+/Mg2+ ratio as healthy African Americans (AA) and healthy Caucasians (CAUC). We measured serum Mg2+ and ionized calcium (Ca2+) with ion-selective electrodes and calculated the serum Ca2+/Mg2+ ratios in patients with SCA and control groups (AA and CAUC). Seventy-four SCA patients and 61 controls were compared. SCA patients had significantly (P < 0.001) lower levels of serum Mg2+ (0.52 +/- 0.05) compared to healthy AA (0.57 +/- 0.04) and CAUC (0.62 +/- 0.03). Eighty-six percent of the adult SCA patients had serum Mg2+ levels below the mean for the AA group, and 96% of SCA patients were above the AA group's mean serum Ca2+/Mg2+. Of the SCA patients studied, 25.6% (95% CI, 16.2-37.2%) had serum Mg2+ levels below the racially adjusted lower limit of normal and 50% (95% Cl, 38.1-61.9%) were above the upper limit of serum Ca2+/Mg2+ for AA controls. By measuring serum Mg2+ and Ca2+, we were able to define a subset of SCA patients with hypomagnesemia and elevated Ca2+/Mg2+ ratios, who may benefit from magnesium supplementation. (C) 2004 Wiley-Liss, Inc.