title: Ionized magnesium levels and the ratio of ionized calcium to magnesium in asthma patients before and after treatment with magnesium.
abstract: OBJECTIVE
  Prior studies have been equivocal about the efficacy of magnesium therapy in acute asthma exacerbations. We hypothesize that pretreatment ionized magnesium (Mg(2+)) levels and/or the ratio of ionized calcium to ionized magnesium (Ca(2+)/Mg(2+)) may have been confounding variables in these previous studies. Here, we report on the incidence of abnormal divalent ion levels in our asthma population.
  
  
  METHODS
  The study was designed as a randomized, double-blind, placebo-controlled trial of intravenous magnesium. Inclusion criteria were: age >18 years, percentage predicted forced expiratory volume (FEV(1)) <75 % after an initial beta-agonist. African-American patients (AA) at an urban university hospital were randomized to 2 g IV Mg or placebo. Mg(2+) and Ca(2+)/Mg(2+) levels were measured pre- and post-infusion. Data were reported as means+/-SD. Student's t-test and Fisher's exact test were used where appropriate (alpha = 0.05, two tailed).
  
  
  RESULTS
  Fifty-five AA patients (mean age of 42.7 years+/-15.6 years, range 18-75 years) were studied. A significantly (p<0.05) lower level of Mg(2+) was found in asthma (AS) patients compared with that in the AA group, by 0.03 mmol/L (95 % CI, 0.007-0.053 mmol/L). The AS group had a mean increase in Ca(2+)/Mg(2+) ratios over the AA group, of 0.27 (95 % CI, 0.16-0.38); 100 % of patients with abnormal divalent ion levels were corrected with IV magnesium.
  
  
  CONCLUSIONS
  We identified a subgroup of asthmatic patients with significant abnormalities in their divalent ion concentrations, which was corrected with IV magnesium.
authors.affiliation: Department of Emergency Medicine, State University of New York, Downstate Medical Center, Brooklyn, NY 11203, USA. nephron1@bellatlantic.net
authors.forename: R
authors.initials: R
authors.lastname: Sinert
authors.forename: M
authors.initials: M
authors.lastname: Spektor
authors.forename: A
authors.initials: A
authors.lastname: Gorlin
authors.forename: C
authors.initials: C
authors.lastname: Doty
authors.forename: A
authors.initials: A
authors.lastname: Rubin
authors.forename: B T
authors.initials: BT
authors.lastname: Altura
authors.forename: B M
authors.initials: BM
authors.lastname: Altura
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001249:Asthma / Q000188:drug therapy* / Q000378:metabolism*; D002118:Calcium / Q000097:blood* / Q000737:chemistry; D005260:Female; D006801:Humans; D007477:Ions / Q000097:blood / Q000737:chemistry / Q000493:pharmacokinetics; D008274:Magnesium / Q000097:blood* / Q000737:chemistry / Q000493:pharmacokinetics / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged
chemical_list: D007477:Ions; D008274:Magnesium; D002118:Calcium