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Table. 1.

Table. 1.

Summary of the results associated with unreliable automated CBC results

Cause Affected CBC parameters Typical resolution method(s)
Lipemia Falsely higher Hb, MCH, and MCHC Perform plasma replacement and rerun
In vitro hemolysis May cause falsely lower RBC count and Hct and falsely higher MCH, and MCHC, May or may not cause falsely higher PLT count Report all CBC results or only WBC count, Hb, MCV, RDW, and smear-verified PLT count
Bilirubin ≥25-35 mg/dL or 250-350 mg/L May cause falsely higher Hb, MCH, and MCHC Dilute the specimen, rerun, and correct the results for dilution
RBC agglutination Falsely lower RBC count and Hctand falsely higher MCV, MCH, and MCHC May or may not cause falsely lower WBC count Incubate the blood specimen at 37°C for 10–15 min and rerun
WBC clumping Falsely lower WBC count Vortex and rerun, or incubate at 37°C for 10–15 min and rerun, or use citrated blood and correct the result for dilution
Platelet clumping Falsely lower PLT count May or may not cause falsely higher WBC count Vortex and rerun, or incubate at 37°C and rerun, or use citrated blood and correct the result(s) for dilution
Hyper/paraproteinemia May cause falsely higher Hb, MCH, and MCHC Perform plasma replacement and rerun
Cryoproteinemia May cause falsely higher WBC count and/or PLT count Incubate at 37°C for 10–20 min and rerun
Organisms May cause falsely higher PLT count May or may not cause falsely higher WBC count Estimate PLT count and if needed, WBC count from blood smear
Glucose ≥ 600 mg/dL or ≥ 33 mmol/L May cause falsely higher MCV and Hct and falsely lower MCHC Dilute the specimen and incubate at RT for 10 min, rerun, and correct the results for dilution or perform a micro-Hct and recalculate MCV and MCHC
Blood stored at RT for 1–4 days Falsely higher MCV and Hct and falsely lower MCHC Reject specimen or report only WBC count, RBC count, Hb, MCH, and smear-verified PLT count
Blood diluted with IV fluid infusion Falsely lower WBC count, RBC count, Hb, Hct, and PLT count Request a properly collected specimen
Adipose tissue (fat globules) May cause falsely higher WBC count Estimate WBC count from blood smear
Fibrin clumps May cause falsely higher WBC count or no results Request a properly collected specimen
Small clot(s) Inaccurate or no results Request a properly collected specimen
RBC fragments MCV < 60 fL, particularly if MCV < 50 fL Falsely higher PLT count Estimate PLT count from blood smear or perform optical PLT count and verify by smear review
Lysis-resistant RBCs May cause falsely higher WBC count, Hb, MCH, and MCHC Dilute the specimen, rerun, and correct the results for dilution
Hyperleukocytosis May cause falsely higher Hb, MCH, MCHC and may or may not cause falsely higher RBC count, MCV, and Hct Dilute the specimen, rerun, and correct the results for dilution
High number of giant PLTs Falsely lower PLT count May or may not cause falsely higher WBC count Estimate PLT and if needed, WBC count(s) from blood smear
Cytoplasmic fragments May cause falsely higher PLT, may or may not cause falsely higher WBC count, and/or RBC count Estimate PLT count and if needed, WBC count from blood smear
PLT satellitosis May cause falsely lower PLT count Vortex and rerun or use citrated blood and correct the result for dilution
NRBCs, megakaryocytes, carcinoma cells Falsely higher uncorrected WBC count Manually correct the uncorrected WBC, as needed

Abbreviations: WBC, white blood cell; RBC, red blood cell; MCV, mean RBC volume; MCH, mean corpuscular Hb content; MCHC, mean corpuscular Hb concentration; PLT, platelet; NRBCs, nucleated red blood cells; RT, room temperature; IV, intravenous.

Ann Lab Med 2022;42:515~530 https://doi.org/10.3343/alm.2022.42.5.515

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