Perchlorate (Irenat®) may falsely lower measured ionised calcium
-
Michael Gruber
,
Carsten Nehring
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 Anesthesio-logy 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).
©2011 by Walter de Gruyter Berlin Boston
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- CCLM Award for The Most Cited Paper Recently Published
- Reviews
- Some views on proteomics in diabetes
- Cancer biomarkers for hepatocellular carcinomas: from traditional markers to recent topics
- Minireviews
- Low-density lipoprotein receptor-related protein 1: new functions for an old molecule
- Could serum measurements of S100 proteins be reliable markers to predict recurrence in meningiomas?
- Opinion Paper
- Focusing on the clinical impact of standardization of creatinine measurements: a report by the EFCC Working Group on Creatinine Standardization
- General Clinical Chemistry and Laboratory Medicine
- Use of a fully automated immunoassay for celiac disease screening in a pediatric population
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