CBC Critical Lab Values

Complete Blood Count (CBC) with Differential Critical Values.

Critical levels of CBC Lab Test:

Hgb: <5 g/dL or >20 g/dL

Hct:<15% or > 60%

WBC: < 500 mm3 or > 50,000/ mm3

Platelets: < 50,000 or > 999,000/mm3

  • Lavender-top tube.

■ A CBC reveals

◆ Information about general health.

◆ Number of red blood cells (RBC).


Following abbreviations used in Lab Test

◆ Total amount of hemoglobin in the blood (Hgb).

◆ Fraction of blood composed of red blood cells (Hct).

◆ Volume of Hgb in each RBC (MCV [mean corpuscular volume]).

◆ Weight of the Hgb in each RBC (MCH [mean corpuscular hemoglobin]).

◆ Proportion of Hgb contained in each RBC (MCHC [mean corpuscular hemoglobin concentration]).

◆ Number of platelets, which are critical to clot formation (see Platelets for more information).

■ MCV, MCH, and MCHC values are useful in the diagnosis of various types of anemia. See below for description of anemias.

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