Perchlorate (Irenat (R)) may falsely lower measured ionised calcium

Gruber, Michael and Nehring, Carsten and Creutzenberg, Marcus and Graf, Bernhard and Hopf, Susanne (2011) Perchlorate (Irenat (R)) may falsely lower measured ionised calcium. CLINICAL CHEMISTRY AND LABORATORY MEDICINE, 49 (6). pp. 1019-1024. ISSN 1434-6621,

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Abstract

Background: Discrepancies in ionised calcium concentrations between results from several point-of-care devices derived from intensive care unit (ICU) patients were postulated to be caused by perchlorate, a thyroid blocking agent. The deviations were serious concerning the diagnosis of hyper- or hypocalcaemia and administration of calcium infusions. Methods: The problem was studied from three perspectives. First: quantification of ionised calcium in heparinised blood samples spiked with sodium perchlorate from healthy volunteers measured using five blood gas analysers (BGAs from IL, Radiometer, Roche and Siemens). Second: verification of clinical concentrations of perchlorate in blood samples after routine use for blood gas analysis from ICU patients. Third: retrospective analysis of data stored from patients during their stay in general ICU of the Departments of Anesthesiology and General Surgery by a patient data management system. Results: Category 1: three of the point-of-care testing devices measure clinically relevant falsely low ionised calcium concentrations when exposed to concentrations perchlorate > 0.1 mmol/L. Two were not able to identify hypercalcaemia of up to 4 mmol/L ionised calcium when specific perchlorate concentrations are exceeded. Category 2: measured clinical concentrations of perchlorate ranged between the lower limit of quantification [LOQ=0.03 mmol/L and 2.75 mmol/L (median=0.29 mmol/L; mean=0.585 mmol/L)]. A concentration above 0.1 mmol/L perchlorate was found in 74.3% of all samples that tested positive. Category 3: between February 2006 and July 2009, 42 patients per year (2.2%) received sodium perchlorate with a median length of treatment of 25 days. Conclusions: Perchlorate causes clinically relevant lowering of measured ionised calcium in BGAs from two providers at concentrations obtained in samples from ICU patients (affecting about 1.1% of all ICU patients).

Item Type: Article
Uncontrolled Keywords: TANDEM MASS-SPECTROMETRY; POTASSIUM PERCHLORATE; ION CHROMATOGRAPHY; APLASTIC ANAEMIA; THYROTOXICOSIS; EXPOSURE; WATER; blood gas analyser; intensive care; ionised calcium; perchlorate Irenat (R) interference; point-of-care testing
Subjects: 600 Technology > 610 Medical sciences Medicine
Divisions: Medicine > Lehrstuhl für Anästhesiologie
Depositing User: Dr. Gernot Deinzer
Date Deposited: 09 Jun 2020 10:42
Last Modified: 09 Jun 2020 10:42
URI: https://pred.uni-regensburg.de/id/eprint/20704

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