Errors encountered in some hematology tests Flashcards
WBC > 100,000/μL, large platelets, cryoglobulin, cryofibrinogen causes in RBC count
High RBCs
Cause of low RBC count
Autoagglutination, cold agglutinins, hemolysis (in vitro), microcytosis, schistocytes, clotting
Cause of high MCV
Autoagglutination, high WBC (>50,000/µL), cold agglutinins, old specimen, hyperosmolar state, reduced red cell deformability
Cause of low MCV
Cryoglobulin, cryofibrinogen, giant platelets, hemolysis (in vitro), swollen red cells
Cause of high MCH
Lipemia, icterus, chylomicrons, high WBC (>50,000/µL), spuriously high Hb, spuriously low RBC
Cause of low MCH
Spuriously low Hb, spuriously high RBC
Cause of high MCHC
Cold agglutinins, autoagglutination, clotting, hemolysis (in vitro and in vivo), spuriously high Hb, falsely low Hct
Cause of low MCHC
High WBC (>50,000/µL), spuriously low Hb, spuriously high Hct
Cause of high hemoglobin
Lipemia, icterus, chylomicrons, lysis-resistant RBCs, WBC > 20,000/μL, platelets > 700 x 10⁹/L, parenteral nutrition, hypergammaglobulinemia, cryoglobulin, cryofibrinogen, hemolysis (in vitro), heparin, hyperbilirubinemia
Cause of low hemoglobin
Clotting
Cause of high hematocrit (microhematocrit)
Dehydration, hemoconcentration, insufficient centrifugation, buffy coat inclusion, hyponatremia, plasma trapping
Cause of low hematocrit (microhematocrit)
Hemolysis (in vitro), improper sealing of capillary tube, excess anticoagulant, tissue fluid contamination, hypernatremia
Cause of high hematocrit (automated)
Cryoglobulin, cryofibrinogen, giant platelets, high WBC (>50,000/µL), hyperglycemia (>600 mg/dL)
Cause of low hematocrit (automated)
Autoagglutination, clotting, hemolysis (in vitro), microcytic red cells
Cause of high WBC count
Lysis-resistant RBCs, nucleated RBCs, megakaryocyte fragments, micromegakaryoblasts, platelet clumps, giant platelets, cryoglobulins, cryofibrinogen, heparin, monoclonal proteins
Cause of low WBC count
Leukemia (with chemotherapy), leukoagglutination, clotting, smudge cells
Cause of low neutrophils
Aggregation or hemosiderin granules counted as eosinophils
Cause of high lymphocytes
Nucleated RBCs, giant platelets, clumps, malarial parasites, hypolobated neutrophils
Cause of high monocytes
Reactive lymphocytes, lymphoblasts, lymphoma cells, immature granulocytes
Cause of high eosinophils
Neutrophils with hemosiderin granules, red cells with malarial pigments
Cause of high platelet count
Leukemia, fragmented RBCs (microangiopathic hemolysis), microorganisms, cryoglobulins, cryofibrinogen, hemolysis (in vitro and in vivo), microcytic RBCs, red cell inclusions, white cell fragments
Cause of low platelet count
Platelet clumps, old specimen, partial clotting, giant platelets, satellitism, cold agglutinins, clotting, heparin
Cause of high MPV
Old specimen, testing MPV too early in EDTA specimen
What must be determined by the lab in consultation with users?
Critical values
Who must be informed of a critical value?
Physician or responsible healthcare worker
What must happen with a critical value?
Documented and referred to the pathologist
When is a preliminary report issued?
After obtaining a critical value
Critical hematocrit values
<21% or >65%
Critical hemoglobin values
<70 g/L or >200 g/L
Critical reticulocyte value
> 20%
Critical WBC count values
<2,000/uL or >50,000/uL (new patient), 1,000 difference if <4,000/uL
What indicates systemic infection on a blood smear?
Neutrophilic phagocytosis of microorganisms
What may indicate hemolytic condition on a blood smear?
Schistocytes
What abnormal forms should be noted on a blood smear?
Sickle cells, blast forms, intracellular organisms
Critical platelet values
<20,000/uL (if not previously reported) or >1 million/uL
Critical prothrombin time value
> 40 seconds
