title: THE EFFECT OF PHLEBOTOMY-INDUCED HEMOLYSIS ON INSULIN LEVEL DETERMINATION.
abstract: OBJECTIVE
  To examine the effect of phlebotomy-induced hemolysis on serum insulin and C-peptide measurement by an immunochemiluminometric assay.
  
  
  METHODS
  As part of a study designed to evaluate β-cell function in a group of adults with newly diagnosed type 2 diabetes, we tested insulin and C-peptide levels in 1,048 samples. In order to evaluate the effect of phlebotomy-induced hemolysis, we determined insulin and C-peptide levels simultaneously in hemolyzed and nonhemolyzed samples.
  
  
  RESULTS
  Forty-seven (4.5%) of the 1,048 samples were affected by hemolysis. In 26 cases, we had paired hemolyzed and nonhemolyzed serum samples that allowed a simultaneous comparison. We found that all degrees of hemolysis led to a significant decrease in insulin level. In hemolyzed serum, the median (interquartile range) of the insulin was 5.6 (1.8 to 24.3) mIU/L, versus 21.3 (11.4 to 48.5) mIU/L in nonhemolyzed serum, representing a 25 to 98% loss. This phenomenon was not found for C-peptide levels.
  
  
  CONCLUSIONS
  Clinicians have to be aware that even a mild degree of phlebotomy-induced hemolysis has a significant effect on serum insulin level determination, which can lead to misinterpretation of test results. This finding has important implications, especially in the evaluation of suspected cases of hyperinsulinemic hypoglycemia.
authors.forename: Taiba
authors.initials: T
authors.lastname: Zornitzki
authors.forename: Moran
authors.initials: M
authors.lastname: Blaychfeld-Magnazi
authors.forename: Hilla
authors.initials: H
authors.lastname: Knobler
authors.forename: Mira
authors.initials: M
authors.lastname: Ulman
mesh_terms: D000368:Aged; D001774:Blood Chemical Analysis / Q000379:methods / Q000592:standards; D002096:C-Peptide / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000097:blood; D005260:Female; D006461:Hemolysis / Q000502:physiology*; D006801:Humans; D007120:Immunochemistry / Q000379:methods / Q000592:standards*; D007328:Insulin / Q000032:analysis* / Q000097:blood*; D008163:Luminescent Measurements / Q000379:methods / Q000592:standards*; D008297:Male; D008875:Middle Aged; D018962:Phlebotomy / Q000009:adverse effects*
chemical_list: D002096:C-Peptide; D007328:Insulin