title: Hemolysis Affects C-Peptide Immunoassay.
abstract: BACKGROUND
  C-peptide is used widely as a marker of insulin secretion, and it participates in the inflammatory response and contributes to the development of coronary artery disease (CAD) in patients with type 2 diabetes mellitus (T2DM). Previous studies have reported that C-peptide measurement was unaffected by hemolysis. However, we found that hemolysis negatively affected C-peptide assay in routine laboratory practice. We further established and validated an individualized hemolysis correction equation to correct and report accurate serum C-peptide results for hemolyzed samples.
  
  
  METHODS
  We studied the effects of hemolysis on C-peptide assay by adding lysed self red blood cells (self-RBCs) to serum. An individualized correction equation was derived. Further, we evaluated the performance of this individualized correction equation by artificially hemolyzed samples.
  
  
  RESULTS
  C-peptide concentration decreased with increasing degree and exposure time of hemolysis. The individualized hemolysis correction equation derived: C-Pcorr= C-Pmeas/(0.969-1.5Hbserum/plasma-5.394 ×10-5Time), which can correct bias in C-peptide measurement caused by hemolysis.
  
  
  CONCLUSIONS
  Hemolysis negatively affects C-peptide measurement. We can correct and report accurate serum C-peptide results for a wide range of degrees of sample hemolysis by individualized hemolysis correction equation for C-peptide assay. This correction would improve diagnostic accuracy and reduce inappropriate therapeutic decisions.
authors.affiliation: Department of Laboratory Medicine, the First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu Province, China.
authors.forename: Zhi-Qi
authors.initials: ZQ
authors.lastname: Wu
authors.affiliation: Department of Laboratory Medicine, the First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu Province, China.
authors.forename: Ju
authors.initials: J
authors.lastname: Lu
authors.affiliation: Department of Laboratory Medicine, the First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu Province, China. huaguoxu@njmu.edu.cn.
authors.forename: Hua-Guo
authors.initials: HG
authors.lastname: Xu
mesh_terms: D001774:Blood Chemical Analysis / Q000379:methods; D002096:C-Peptide / Q000097:blood*; D005260:Female; D006454:Hemoglobins / Q000378:metabolism; D006461:Hemolysis; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D013997:Time Factors
chemical_list: D002096:C-Peptide; D006454:Hemoglobins
keywords: C-peptide; hemolysis; hypoglycemia; individualized correction