Evaluation of a New Automated Routine Measurement for Serum Adjusted Ionized Calcium (at pH 7.4) in Patients Suspected of Calcium Metabolic Disease

• Published in: The journal of applied laboratory medicine 2020-07, Vol.5 (4), p.704-715
• Main Authors: Kur, Dår K, Hillig, Thore, Hansen, Steen I, Goharian, Tina, Witte, Majbritt L, Thode, Jorgen
• Format: Article
• Language: English
• ISSN: 2576-9456; 2475-7241
• DOI: 10.1093/jalm/jfaa006

BACKGROUNDTotal calcium is a less accurate test in predicting ionized calcium (Ca2+) in patients suspected of calcium metabolic disease. Nevertheless, total calcium continues to be used as routine measurement instead of adjusted Ca2+ (at pH 7.4). In the current study we evaluate a new multichannel instrument, the ISE Module E1200 for adjusted Ca2+ (at pH 7.4), containing three different ion-selective electrode (ISE) units. METHODSSerum from 1350 patients was compared to the ABL835 flex and KoneLab. Total calcium was also evaluated on the Dimension Vista 1500 system. Correlations between instruments were assessed by Deming regression and degree of agreement by Cohen's kappa (κ). RESULTSAnalytical imprecisions for the three ISE units for adjusted Ca2+ (at pH 7.4) was between 0.36% and 2.52%, and for pH between 0.32% and 3.24%. Results were comparable for each ISE unit (r = 0.797-0.917; all P