Hypomagnesemia in trauma patients

The objective of this study was to determine the incidence of hypomagnesemi a in injured patients (versus a general hospital cohort) and to compare tot al and ionized values with each other and with the incidence of injury seve rity and ethanol level. It was a descriptive study of consecutive injured p atients at a level II trauma center. For 3 months subjects underwent admiss ion paired analysis of blood total magnesium (TMg) and ionized magnesium (I Mg). IMg was determined by microanalysis of whole blood (Nova Biomedical, N ovaSP9). During the same time period, all hospital samples for TMg (m = 130 8) underwent simultaneous IMg testing. Pearson correlation coefficients wer e determined for IMg versus TMg, Injury Severity Score (ISS), Trauma Score (TS), Glasgow Coma Scale (GCS), and blood units transfused. By convention, hypomagnesemia was defined as TMg less than or equal to 1.6 mg/dl and IMg l ess than or equal to 0.5 mg/dl. Altogether 43% of 113 trauma patients had l ow magnesium levels compared to 30% of noninjured cohorts (p < 0.05). The c orrelation coefficient (r(2)) for TMg and IMg was 0.74 for TMg values > 1.6 , but for TMg less than or equal to 1.6 the r(2) was 0.35. Coefficients for IMg and ISS, TS, GCS, units transfused, and ethanol level were 0.06, 0.08, 0.10, 0.04, and 0.01, respectively. Mean Wig was 0.57 +/- 0.09 mg/dl,vith ethanol ingestion and 0.56 +/- 0.06 mg/dl without ethanol ingestion (mean /- SD, p > 0.05). It was concluded that hypomagnesia is common in injured p atients but does not correlate with indices of injury severity or ethanol l evel. TMg is not a good predictor of IMg at low levels. Trauma patients may benefit from determination of IMg for accurate diagnosis of a low Mg level to facilitate repletion.