title: Hemolysis is a major cause of variability in insulin measurement during oral glucose tolerance test in children.
abstract: BACKGROUND
  The oral glucose tolerance test (OGTT) is widely employed to evaluate insulin resistance in children with growth hormone deficiency. Due to the difficulty in blood sampling, hemolysis is a frequent pre-analytic interference. The present study was performed to characterize the effects of hemolysis on insulin assays, in order to assess the need to generate automatic hemolysis reports and/or to reject hemolyzed samples.
  
  
  METHODS
  Insulin plasma levels were measured using a Siemens ADVIA Centaur on samples obtained from children with suspected GH deficiency at risk for insulin resistance during OGTT.
  
  
  RESULTS
  The presence of hemolysis (with a concentration of free hemoglobin above 75 mg/dL) promotes a dose- and time-dependent decrease in immunoreactive insulin at any time-point evaluated during OGTT. As a consequence, the variability of insulin is particularly high (often exceeding 100% of the mean value) as compared to that of glucose. This variability is markedly reduced after removal of the hemolyzed samples.
  
  
  CONCLUSIONS
  When hemolysis is not taken into account a misinterpretation of insulin secretion pattern can occur. It is therefore imperative to: (i) analyze blood samples immediately after sampling, (ii) reject samples with a concentration of free hemoglobin equal to or above 125 mg/dL and (iii) always report the possible interference.
authors.affiliation: Dept of Medical Sciences, University Amedeo Avogadro of East Piedmont, Novara, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Bellomo
authors.forename: Maria Giovanna
authors.initials: MG
authors.lastname: Sulas
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Mairate
authors.forename: Maria Beatrice
authors.initials: MB
authors.lastname: Bardone
authors.forename: Roberta
authors.initials: R
authors.lastname: Rolla
mesh_terms: D000293:Adolescent; D001786:Blood Glucose / Q000032:analysis; D003951:Diagnostic Errors; D005260:Female; D018149:Glucose Intolerance / Q000097:blood / Q000175:diagnosis*; D005951:Glucose Tolerance Test; D006130:Growth Disorders / Q000097:blood / Q000175:diagnosis*; D006461:Hemolysis; D019382:Human Growth Hormone / Q000009:adverse effects / Q000097:blood / Q000172:deficiency*; D006801:Humans; D007328:Insulin / Q000097:blood*; D007333:Insulin Resistance / Q000502:physiology; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results
chemical_list: D001786:Blood Glucose; D007328:Insulin; D019382:Human Growth Hormone