White Blood Cell Count and Differential
| See Also | Lab Tests |
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A white blood cell count and differential is part of the complete blood count. It is helpful in the evaluation of infection, allergy, neoplasm or immunosuppression.[1], [2]
Discussion
The white blood cell count and differential is a measure of the total number of white blood cells and it measures the percentage of each type of leukocyte present in the blood. The different leukocytes include:
Patient Preparation
- Fasting is not required for this test.
Interfering Factors:
- Eating, physical activity and stress may increase the WBC count and alter the differential values.
- Pregnancy in the final month and labor may increase the WBC level.
- WBC count tends to be lower in the morning and higher in the late afternoon.
- Newborns tend to have higher normal WBC counts, whereas the elderly often have lower WBC counts even when faced with an infection.
- Drugs that may caused increased WBC levels include adrenaline, allopurinol, aspirin, chloroform, epinephrine, heparin, quinine, steroids, an triamterene.
- Drugs that may cause decreased WBC levels include antibiotics, anticonvulsants, antihistamines, antimetabolites, antithyroid]] drugs, arsenicals, barbituates, chemotherapeutic agents, diuretics, and sulfonamides.
Clinical Implications
A WBC is typically used to assess for or monitor infection, inflammation, necrosis or leukemic neoplasia. Other indications include:
High levels (referred to as leukocytosis) indicates:
- Infection. The levels or neutrophils, lymphocytes, monocytes and eosinophils helps to determine the specific type of infection.
- trauma, stress or hemorrhage
- inflammation
- dehydration
- tissue necrosis
- thyroid storm
- steroid use
- Leukemic neoplasia or other myeloproliferative disorders
- malignancy
Low levels (referred to as leukopenia) indicates:
- chronic or overwhelming infections
- dietary deficiencies
- drug toxicity
- congenital marrow aplasia
- bone marrow infiltration
- autoimmune disease
- hyperspenism
Associated Tests
The following white blood cell differentials are typically included: neutrophils, lymphocytes, monocytes, eosinophils and basophils. Other tests associated with a WBC count include lymphocyte immunophenotyping and peripheral blood smear.
References
- ↑ Pagana Kathleen D, Pagana Timothy J (2006) Mosby's Manual of Diagnostic and Laboratory Tests, Mosby.
- ↑ Weatherby Dicken, Ferguson Scott (2002) Blood Chemistry and CBC Analysis: Clinical Laboratory Testing from a Functional Perspective, Bear Mountain.
