title: The effect of perchlorate medication on point-of-care testing.
abstract: BACKGROUND
  To create awareness for mismeasurements of ion-selective electrodes caused by patients' medications and to prevent severe consequences in an intensive care therapy.
  
  
  METHODS
  A 73-year-old woman presented with severe carbimazol-induced toxic epidermal necrolysis. After replacement of carbimazol by sodiumperchlorate, we detected a huge discrepancy in the measurement of ionised calcium by two different Point-of-Care (POCT) systems. While Siemens Rapidlab 865 showed a severe hypocalcemia at all times, the Radiometer 600 system first presented a severe hypercalcemia and, in the course of the following days, also a hypocalcemia but with significantly (p < 10 to the -45) higher values than the Rapidlab system. Furthermore, the POCT systems detected a pseudohypocalcemia at times where we think there was a normo- or even hypercalcemia which led to incorrect therapy with excessive substitution of ionised calcium.
  
  
  CONCLUSIONS
  The substance sodiumperchlorate, which is well established in Europe for hyperthyreosis therapy, caused malfunctions of analyses of ionised calcium by POCT systems.
authors.affiliation: Department of Anesthesiology, University of Regensburg, Regensburg, Germany. Susanne.Hopf@klinik.uni-regensburg.de
authors.forename: Susanne
authors.initials: S
authors.lastname: Hopf
authors.forename: Monika
authors.initials: M
authors.lastname: Bäumel
authors.forename: Michael
authors.initials: M
authors.lastname: Gruber
authors.forename: Thomas
authors.initials: T
authors.lastname: Bein
authors.forename: Marcus
authors.initials: M
authors.lastname: Creutzenberg
authors.forename: Bernhard
authors.initials: B
authors.lastname: Graf
authors.forename: Michael
authors.initials: M
authors.lastname: Pawlik
mesh_terms: D000368:Aged; D013956:Antithyroid Agents / Q000737:chemistry*; D016477:Artifacts; D001774:Blood Chemical Analysis; D002118:Calcium / Q000097:blood / Q000737:chemistry*; D003951:Diagnostic Errors / Q000517:prevention & control; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D006996:Hypocalcemia / Q000139:chemically induced / Q000175:diagnosis; D010472:Perchlorates / Q000737:chemistry*; D019095:Point-of-Care Systems; D017670:Sodium Compounds / Q000737:chemistry*
chemical_list: D013956:Antithyroid Agents; D010472:Perchlorates; D017670:Sodium Compounds; C031068:sodium perchlorate; D002118:Calcium