title: Studies on in vitro hemolysis and utility of corrective formulas for reporting results on hemolyzed specimens.
abstract: BACKGROUND
  Spuriously hemolyzed specimens are the most common preanalytical problems in clinical laboratories. Corrective formulas have been proposed to allow the laboratory to release test results on these specimens. This study aimed to assess the influence of spurious hemolysis and reliability of corrective formulas.
  
  
  METHODS
  Blood collected into lithium heparin vacuum tubes was divided in aliquots and subjected to mechanical injury by aspiration with an insulin syringe equipped with a thin needle (30 gauge). Each aliquot (numbered from "#0" to "#5") was subjected to a growing number of passages through the needle, from 0 to 5 times. After hematological testing, plasma was separated by centrifugation and assayed for lactate dehydrogenase (LD), aspartate aminotransferase (AST), potassium and hemolysis index (HI).
  
  
  RESULTS
  Cell-free hemoglobin concentration gradually increased from aliquot #0 (HI: 0) to #5 (HI: 76 +/- 22, cell-free hemoglobin approximately 37.0 g/L). A highly significant inverse correlation was observed between HI and red blood cell count (RBC), hematocrit, mean corpuscular volume (MCV), LD, AST, potassium, whereas the correlation was negative with mean corpuscular hemoglobin (MCH). No correlation was found with hemoglobin, platelet count and glucose. A trend towards decrease was also observed for white blood cells count. The ANCOVA comparison of analyte-specific regression lines from the five subjects studied revealed significant differences for all parameters except potassium. In all circumstances the sy,x of these equations however exceeded the allowable clinical bias.
  
  
  CONCLUSIONS
  Mechanical injury of blood, as it might arise from preanalytical problems, occurs dishomogeneously, so that corrective formulas are unreliable and likely misleading.
authors.affiliation: U.O. Diagnostica Ematochimica, Dipartimento di Patologia e Medicina di Laboratorio, Azienda Ospedaliero-Universitaria di Parma, Parma, Italy. glippi@ao.pr.it
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Lippi
authors.forename: Paola
authors.initials: P
authors.lastname: Avanzini
authors.forename: Fernanda
authors.initials: F
authors.lastname: Pavesi
authors.forename: Mirco
authors.initials: M
authors.lastname: Bardi
authors.forename: Luigi
authors.initials: L
authors.lastname: Ippolito
authors.forename: Rosalia
authors.initials: R
authors.lastname: Aloe
authors.forename: Emmanuel J
authors.initials: EJ
authors.lastname: Favaloro
mesh_terms: D001772:Blood Cell Count; D001793:Blood Preservation / Q000009:adverse effects* / Q000592:standards; D001800:Blood Specimen Collection / Q000009:adverse effects / Q000379:methods / Q000592:standards; D003627:Data Interpretation, Statistical; D004909:Erythrocyte Indices / Q000502:physiology; D006403:Hematologic Tests / Q000379:methods / Q000592:standards* / Q000706:statistics & numerical data; D006454:Hemoglobins / Q000032:analysis; D006461:Hemolysis / Q000502:physiology*; D006801:Humans; D016014:Linear Models; D015588:Observer Variation; D011237:Predictive Value of Tests; D012107:Research Design / Q000592:standards; D013223:Statistics as Topic
chemical_list: D006454:Hemoglobins