Causes of spurious results on the automated CBC

Parameter	Spuriously increased by	Spuriously decreased by
RBC count	High WBC count	Cold agglutinins Hemolysis*
Hemoglobin	High WBC count Lipemia Cryoglobulins Immunoglobulins Artificial hemoglobin-containing solutions Hemolysis*
MCHC	Spuriously high hemoglobin Spuriously low RBC count	Hyperglycemia Specimen storage for >24 hours
MCV	High WBC count Cold agglutinins Severe hyperglycemia Hypernatremia Specimen storage for >24 hours	Hyponatremia
RET count	Cellular interferences NRBCs RBC inclusions Autofluorescence due to drugs Paraproteins Cold agglutinins Hemolysis*
WBC count	Clotted sample Giant platelets (miscounted as WBCs) Platelet clumps (miscounted as WBCs) Cryoglobulins Lipids Insufficiently lysed RBCs NRBCs (miscounted as WBCs) Microorganisms (miscounted as WBCs)	Neutrophil agglutination
PLT count	Schistocytes^¶ (miscounted as PLTs) Cytoplasmic fragments (miscounted as PLTs) Cryoglobulins Bacteria or fungi (miscounted as PLTs) Lipids	Platelet clumps WBC satellitism Clotted sample Giant platelets (miscounted as WBCs)

Includes causes related to phlebotomy as well as clinical conditions. Refer to UpToDate for information on proper specimen handling and details of evaluating abnormal results.

RBC: red blood cell; RET: reticulocyte; WBC: white blood cell; MCHC: mean corpuscular hemoglobin concentration; MCV: mean corpuscular volume; NRBCs: nucleated red blood cells; PLT: platelet.

* Hemolysis refers to hemolysis that occurs in vitro, such as with rapid phlebotomy with a small needle. In vivo hemolysis can also cause true (not spurious) anemia and changes to the RBC parameters.

¶ While 1 or 2 schistocytes may be formed during slide preparation, more than 1 or 2 schistocytes indicates a potentially serious problem and should be evaluated without delay.

Adapted from: Chabot-Richards DS, Zhang QY, George TI. Automated hematology. In: Tietz Textbook of Laboratory Medicine, 7th ed, Nader R (Ed), Elsevier 2023.

Graphic 141504 Version 2.0

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Causes of spurious results on the automated CBC