title: Analytical evaluation of Kone Microlyte determination of ionized magnesium.
abstract: We performed an analytical evaluation of a commercially available instrument for determining ionized magnesium through use of a neutral carrier, liquid-membrane-based ion-selective electrode. Reproducibility (CV 2-4%), linearity (0.30-2.50 mmol/L), lower limit of detection (0.30 mmol/L), and absence of interference from Ca2+ indicate adequate performance for measuring ionized magnesium in plasma or serum samples in the normal to high-concentration range. Sodium in excess of 150 mmol/L caused a negative bias, which can be explained by ionic strength-induced changes in activity coefficients. The use of heparin as an anticoagulant must be restricted to concentrations < 15 units/mL because of the binding of magnesium to heparin. The mean +/- SD concentration of ionized magnesium and its fraction of total magnesium in 76 healthy volunteers were 0.56 +/- 0.05 mmol/L and 0.65 +/- 0.04, respectively.
authors.affiliation: Academic Medical Centre, Dept. of Clinical Chemistry, Amsterdam, The Netherlands.
authors.forename: H E
authors.initials: HE
authors.lastname: van Ingen
authors.forename: H J
authors.initials: HJ
authors.lastname: Huijgen
authors.forename: W T
authors.initials: WT
authors.lastname: Kok
authors.forename: G T
authors.initials: GT
authors.lastname: Sanders
mesh_terms: D000293:Adolescent; D000328:Adult; D000925:Anticoagulants; D002118:Calcium / Q000097:blood; D002624:Chemistry, Clinical / Q000295:instrumentation* / Q000706:statistics & numerical data; D004566:Electrodes; D005260:Female; D006493:Heparin / Q000097:blood; D006801:Humans; D008094:Lithium / Q000097:blood; D008274:Magnesium / Q000097:blood*; D008297:Male; D008875:Middle Aged; D009994:Osmolar Concentration; D011786:Quality Control; D012016:Reference Values; D012680:Sensitivity and Specificity; D012964:Sodium / Q000097:blood
chemical_list: D000925:Anticoagulants; D006493:Heparin; D008094:Lithium; D012964:Sodium; D008274:Magnesium; D002118:Calcium