A Methodical Approach to Interpreting the White Blood Cell Parameters of the Complete Blood Count

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Figure 1.
The formula for correcting the WBC for the presence of NRBCs is shown
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Figure 2.
The calculation of relative differential values is shown
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Figure 3.
The calculation of absolute values from relative differential percentages is shown.

Table 1.

Steps for interpreting the white blood cell parameters of a complete blood count.

Step 1.	Ensure that NRBCs or other conditions are not falsely affecting the WBC; correct the WBC if needed, before proceeding.
Step 2.	Examine the WBC for variations in the total number of wbcs.
Step 3.	Interpret absolute differential counts against appropriate reference intervals using proper terminology.
Step 4.	If absolute counts are not available from an instrument, use relative counts (i.e. percentages) to calculate absolute values.
Step 5.	Make note of immature cells in any leukocyte cell line reported in the differential that should not appear in normal peripheral blood.
Step 6.	Make note of any morphological abnormalities of wbcs.
Step 7.	Correlate the wbc findings with rbc and platelet findings for a complete clinical assessment of the patient's blood picture.

Table 3.

White blood cell parameters for Case 1.

	Patient	Pediatric Reference Interval
WBC (× 10³ wbc/μL)	18.3	5.5-15.0

Differential	(%)	PEDIATRIC RELATIVE (%)	PEDIATRIC ABSOLUTE (× 10³ /μL)
Neutrophils	45	30-50	1.5-7.5
Bands	15	0-5	0.0-0.8
Lymphocytes	33	40-55	2.0-8.3
Monocytes	7	0-5	0.0-2.0
Eosinophils	0	0-2	0.0-0.7
Basophils	0	0-1	0.0-0.3
Patient Morphology	14 NRBC/100 wbcs, toxic granulation, vacuolization of neutrophils

Table 4.

Calculations of absolute white blood cell values for Case 1.

Cell Type	Calculation	Total numbers
Neutrophilic cells (Neutrophils + bands = 60% neutrophilic cells)	16.0 × 10³/μL × 60%/100%	9.6 × 10³ cells/μL
Lymphocytes	16.0 × 10³/μL × 33%/100%	5.3 × 10³ cells/μL
Monocytes	16.0 × 10³/μL × 7%/100%	1.1 × 10³ cells/μL

Table 5.

White blood cell parameters for Case 2.

	Patient	Adult Reference Interval
WBC (× 10³ wbc/μL)	19.3	5.5-15.0

Differential	(%)	(× 10³/μL)	ADULT RELATIVE (%)	ADULT ABSOLUTE (× 10³/μL)
Neutrophils	58	11.2	40-75	1.8-7.9
Bands	2	0.4	0-5	0.0-0.5
Lymphocytes	23	4.4	20-40	0.9-4.2
Monocytes	9	1.7	0-9	0.0-0.9
Eosinophils	5	1.0	1-6	0.05-0.6
Basophils	3	0.6	0-2	0.0-0.2
Patient Morphology

Table 6.

White blood cell parameters for Case 6.

	Patient	Adult Reference Interval
WBC(× 10³ wbc/μL)	45	4.5 – 10. 5

Differential	(%)	ADULT RELATIVE (%)	ADULT ABSOLUTE (× 10³ /μL)
Neutrophils	16	40-75	1.8-7.9
Bands	0	0-5	0.0-0.5
Metamyelocytes	0	0
Myelocytes	19	0
Promyelocytes	16	0
Blasts	42	0
Lymphocytes	6	20-40	0.9-4.2
Monocytes	1	0-9	0.0-0.9
Eosinophils	0	1-6	0.05-0.6
Basophils	0	0-2	0.0-0.2
Patient Morphology		Auer rods noted

Table 7.

Calculations of the absolute differential counts for Case 3.

Cell Type	Calculation	Total numbers
Neutrophilic cells (without blasts)	45.0 × 10³ wbcs/μL × 51%/100%	23.0 × 10³ cells/μL
Neutrophilic cells (including blasts)	45.0 × 10³ wbcs/μL × 93%/100%	41.9 × 10³ cells/μL
Lymphocytes	45.0 × 10³ wbcs/μL × 6 %/100%	2.7 × 10³ cells/μL
Monocytes	16.0 × 10³/μL × 7%/100%	1.1 × 10³ cells/μL