title: 70-year old female patient with mismatch between hematocrit and hemoglobin values: the effects of cold agglutinin on complete blood count.
abstract: BACKGROUND
  There are a number of pre-analytical and analytical factors, which cause false results in the complete blood count. The present case identifies cold agglutinins as the cause for the mismatch between hematocrit and hemoglobin values.
  
  
  METHODS
  70-year old female patient had a history of cerebrovascular diseases and rheumatoid arthritis. During routine laboratory examination, the patient had normal leukocyte and platelet counts; however, the hemoglobin (Hb: 105 g/L) and hematocrit (HCT: 0.214 L/L) results were discordant. Hemolysis, lipemia and cold agglutinin were evaluated as possible reasons for the mismatch between hematocrit and hemoglobin values.
  
  
  RESULTS
  First blood sample was slightly hemolysed. Redrawn sample without hemolysis or lipemia was analyzed but the mismatch became even more distinct (Hb: 104 g/L and HCT: 0.08 L/L). In this sample, the titration of the cold agglutinin was determined and found to be positive at 1:64 dilution ratios. After an incubation of the sample at 37°C for 2 hours, reversibility of agglutination was observed.
  
  
  CONCLUSIONS
  We conclude that cold agglutinins may interfere with the analysis of erythrocyte and erythrocyte-related parameters (HCT, MCV, MCH and MCHC); however, Hb, leukocyte and platelet counts are not affected.
authors.affiliation: Department of Clinical Biochemistry, Lüleburgaz State Hospital, Kırklareli, Turkey.
authors.forename: Serif
authors.initials: S
authors.lastname: Ercan
authors.affiliation: Departments of Clinical Microbiology, Lüleburgaz State Hospital, Kırklareli, Turkey.
authors.forename: Mustafa
authors.initials: M
authors.lastname: Calışkan
authors.affiliation: Home Health Services, Lüleburgaz State Hospital, Kırklareli, Turkey.
authors.forename: Erhan
authors.initials: E
authors.lastname: Koptur
mesh_terms: D000368:Aged; D001772:Blood Cell Count; D001800:Blood Specimen Collection / Q000009:adverse effects / Q000379:methods; D003080:Cold Temperature / Q000009:adverse effects; D003450:Cryoglobulins / Q000494:pharmacology / Q000502:physiology; D003951:Diagnostic Errors; D004912:Erythrocytes / Q000166:cytology / Q000187:drug effects*; D005260:Female; D006400:Hematocrit; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D012621:Seasons
chemical_list: D003450:Cryoglobulins; D006454:Hemoglobins; C029443:cold agglutinins
keywords: cold agglutinin; complete blood count; hematocrit; hemoglobin; interference