Evaluation of 2 portable ion-selective electrode meters for determining whole blood, plasma, urine, milk, and abomasal fluid potassium concentrations in dairy cattle

A. A. Megahed, M. W.H. Hiew, W. Grünberg, P. D. Constable

Research output: Contribution to journalArticlepeer-review

Abstract

Two low-cost ion-selective electrode (ISE) handheld meters (CARDY C-131, LAQUAtwin B-731; Horiba Ltd., Albany, NY) have recently become available for measuring the potassium concentration ([K+]) in biological fluids. The primary objective of this study was to characterize the analytical performance of the ISE meters in measuring [K+] in bovine whole blood, plasma, urine, milk, and abomasal fluid. We completed 6 method comparison studies using 369 whole blood and plasma samples from 106 healthy periparturient Holstein-Friesian cows, 138 plasma samples from 27 periparturient Holstein-Friesian cows, 92 milk samples and 204 urine samples from 16 lactating Holstein-Friesian cows, and 94 abomasal fluid samples from 6 male Holstein-Friesian calves. Deming regression and Bland-Altman plots were used to characterize meter performance against reference methods (indirect ISE, Hitachi 911 and 917; inductively coupled plasma-optical emission spectroscopy). The CARDY ISE meter applied directly in plasma measured [K+] as being 7.3% lower than the indirect ISE reference method, consistent with the recommended adjustment of +7.5% when indirect ISE methods are used to analyze plasma. The LAQUAtwin ISE meter run in direct mode measured fat-free milk [K+] as being 3.6% lower than the indirect ISE reference method, consistent with a herd milk protein percentage of 3.4%. The LAQUAtwin ISE meter accurately measured abomasal fluid [K+] compared to the indirect ISE reference method. The LAQUAtwin ISE meter accurately measured urine [K+] compared to the indirect ISE reference method, but the median measured value for urine [K+] was 83% of the true value measured by inductively coupled plasma-optical emission spectroscopy. We conclude that the CARDY and LAQUAtwin ISE meters are practical, low-cost, rapid, accurate point-of-care instruments suitable for measuring [K+] in whole blood, plasma, milk, and abomasal fluid samples from cattle. Ion-selective electrode methodology is not suitable for measuring [K+] in bovine urine.

Original languageEnglish (US)
Pages (from-to)7330-7343
Number of pages14
JournalJournal of Dairy Science
Volume99
Issue number9
DOIs
StatePublished - Sep 1 2016

Keywords

  • hypokalemia
  • point-of-care

ASJC Scopus subject areas

  • Food Science
  • Animal Science and Zoology
  • Genetics

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