Journal of Analytical Methods in Chemistry

Journal of Analytical Methods in Chemistry / 1991 / Article

Open Access

Volume 13 |Article ID 427284 | https://doi.org/10.1155/S1463924691000391

A. B. T. J. Boink, B. M. Buckley, T. F. Christiansen, A. K. Covington, A. H. J. Maas, O. Müller-Plathe, Ch. Sachs, O. Siggaard-Andersen, "IFCC recommendation on sampling, transport and storage for the determination of the concentration of ionized calcium in whole blood, plasma and serum", Journal of Analytical Methods in Chemistry, vol. 13, Article ID 427284, 5 pages, 1991. https://doi.org/10.1155/S1463924691000391

IFCC recommendation on sampling, transport and storage for the determination of the concentration of ionized calcium in whole blood, plasma and serum

Abstract

The substance concentration of ionized calcium (cCa2+) in blood, plasma or serum preanalytically may be affected by pH changes of the sample, calcium binding by heparin, and dilution by the anticoagulant solution.pH changes in whole blood can be minimized by anaerobic sampling to avoid loss of Co2, by measuring as soon as possible, or by storing the sample in iced water to avoid lactic acid formation. cCa2+ and pH should be determined simultaneously.Plasma or serum: If centrifuged in a closed tube, and measured immediately, the pH of the sample will be close to the original value. If a delay has occurred between centrifugation and the measurement, causing substantial loss of Co2, equilibration of the sample with a gas mixture corresponding to pCO2= 5.3 kPa prior to the measurement is recommended. Conversion of the measured values to cCa2+ (7.4) is only valid if the pH is in the range 7.2-7.6.Ca2+ binding by heparin can be minimized by using either of the following:(1) A final concentration of sodium or lithium heparinate of 15 IU/ml blood or less(2) Calcium titrated heparin with a final concentration of less than 50 IU/ml blood.Dilution effect can be avoided by use of dry heparin in capillaries or syringes. When heparin solutions are used, errors due to dilution or calcium binding can be reduced by using syringes with a heparin solution containing free calcium ions corresponding to the mean concentration of ionized calcium in normal plasma.Conditions for blood collection, storage, and transport to avoid preanalytical errors are described in this paper.

Copyright © 1991 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


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