White Blood Cell Count, Blood Smear and Differential

General

Core Lab Study

Synonym/Acronym:
leukocyte count, white cell count, WBC with diff.

Rationale
To evaluate bacterial, parasitic, and viral infections; to assist in diagnosing conditions related to immune response such as asthma, dermatitis, and hay fever; and to assist in diagnosing and monitoring leukemic disorders.

This Core Lab Study is part of a complete blood count (CBC), one of the most requested laboratory studies, and is included in the Anemia profile, General Health panel, and Obstetric panel.

Patient Preparation
There are no food, fluid, activity, or medication restrictions unless by medical direction.

Normal Findings
Method: Automated, computerized, multichannel analyzers, flow cytometry. Many analyzers can determine a five- or six-part WBC differential. The six-part automated WBC differential identifies and enumerates neutrophils, lymphocytes, monocytes, eosinophils, basophils, and immature granulocytes (IG), where IG represents the combined enumeration of promyelocytes, metamyelocytes, and myelocytes as both an absolute number and a percentage. The five-part WBC differential includes all but the immature granulocyte parameters.


WBC Count and Differential
AgeConventional Units WBC × 103/microLNeutrophilsLymphocytesMonocytesEosinophilsBasophils
(Absolute) and %(Absolute) and %(Absolute) and %(Absolute) and %(Absolute) and %
Birth9.1–30.1(5.5–18.3) 24%–58%(2.8–9.3) 26%–56%(0.5–1.7) 7%–13%(0.02–0.7) 0%–8%(0.1–0.2) 0%–2.5%
1–23 mo6.1–17.5(1.9–5.4) 21%–67%(3.7–10.7) 20%–64%(0.3–0.8) 4%–11%(0.2–0.5) 0%–3.3%(0–0.1) 0%–1%
2–10 yr4.5–13.5(2.4–7.3) 30%–77%(1.7–5.1) 14%–50%(0.2–0.6) 4%–9%(0.1–0.3) 0%–5.8%(0–0.1) 0%–1%
11 yr–older adult4.5–11.1(2.7–6.5) 40%–75%(1.5–3.7) 12%–44%(0.2–0.4) 4%–9%(0.05–0.5) 0%–5.5%(0–0.1) 0%–1%
*SI Units (conventional units × 1 or WBC count × 109/L).

WBC Count and Differential
AgeImmature Granulocytes (Absolute) (103/microL)Immature Granulocyte Fraction (IGF) (%)
Birth–9 yr0–0.030%–0.4%
10 yr–older adult0–0.090%–0.9%

Reference values for the WBC count vary across the age continuum and with physical condition. For example, counts are affected by high levels of physical activity or stress (e.g., labor and delivery). Thus, the time of collection and the activity status of the patient should be taken into consideration when reviewing or comparing WBC counts.

Critical Findings and Potential Interventions

  • Total WBC count of less than 2 × 103/microL (SI: Less than 2 × 109/L)
  • Absolute neutrophil count of less than 0.5 × 103/microL (SI: Less than 0.5 × 109/L)
  • Total WBC count of greater than 40 × 103/microL (SI: Greater than 40 × 109/L)

Timely notification to the requesting health-care provider (HCP) of any critical findings and related symptoms is a role expectation of the professional nurse. A listing of these findings varies among facilities.

Consideration may be given to verifying the critical findings before action is taken. Policies vary among facilities and may include requesting immediate recollection and retesting by the laboratory.

The presence of abnormal cells, other morphological characteristics, or cellular inclusions may signify a potentially life-threatening or serious health condition and should be investigated. Examples are hypersegmented neutrophils, agranular neutrophils, blasts or other immature cells, Auer rods, Döhle bodies, marked toxic granulation, and plasma cells.

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