title: Weak relationship between ionized and total magnesium in serum of patients requiring magnesium status.
abstract: Measurement and monitoring of magnesium (Mg) are important to prevent the development of serious and potentially fatal complications in critically ill patients. Although ion-selective electrodes are available and earlier reports suggest that free ionized magnesium (iMg2+) is the most useful test to estimate Mg status, most clinical laboratories still only measure total Mg. To compare the relationship among iMg2+, total Mg, and albumin in serum, samples were collected from 48 consecutive patients admitted to an intensive care unit or a primary health center. The mean serum level of iMg2+ in 44 patients was 0.53 mmol/L, the total Mg was 0.96 mmol/L, and the albumin was 34.93 g/L. The correlation between iMg2+ and total Mg in serum was r=0.585; the correlation between iMg2+ and albumin in serum was r=378; and the correlation between total Mg and albumin in serum was r=0.340. The mean percent iMg2+ in relation to total Mg in serum was calculated to be 55% in the patient samples. The important level of biologically active iMg2+ was not reflected upon analysis of total Mg in 25% of consecutive patients. This report shows that the correlation of iMg2+ and total Mg is weak, not only in critically ill patients but also in patients in whom Mg status is inquired as a whole.
authors.affiliation: Department of Natural Sciences, School of Health Sciences, Jönköping University, Jönköping, Sweden.
authors.forename: Mona
authors.initials: M
authors.lastname: Johansson
authors.forename: Per A
authors.initials: PA
authors.lastname: Whiss
mesh_terms: D000328:Adult; D002413:Cations, Divalent / Q000097:blood / Q000737:chemistry; D005260:Female; D006262:Health; D006801:Humans; D008274:Magnesium / Q000097:blood* / Q000737:chemistry*; D008275:Magnesium Deficiency / Q000097:blood*; D008297:Male; D008875:Middle Aged; D012709:Serum Albumin / Q000378:metabolism
chemical_list: D002413:Cations, Divalent; D012709:Serum Albumin; D008274:Magnesium