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Introduction ⬇

WBCs (leukocytes) are divided into two main groups: granulocytes and agranulocytes. The granulocytes receive their name from the distinctive granules that are present in the cytoplasm of neutrophils, basophils, and eosinophils. However, each of these cells also contains a multilobed nucleus, which accounts for their also being called polymorphonuclear (PMN) leukocytes. In laboratory terminology, they are often called “polys” or PMNs. The agranulocytes, which consist of the lymphocytes and monocytes, do not contain distinctive granules and have nonlobular nuclei that are not necessarily spherical. The term mononuclear leukocytes is applied to these cells.

The endocrine system is an important regulator of the number of leukocytes in the blood. Hormones affect the production of leukocytes in the blood-forming organs, their storage and release from the tissue, and their disintegration. A local inflammatory process exerts a definite chemical effect on the mobilization of leukocytes. The lifespan of leukocytes varies from 13 to 20 days, after which the cells are destroyed in the lymphatic system; many are excreted from the body in fecal matter.

Leukocytes fight infection and defend the body by a process called phagocytosis, in which the leukocytes actually encapsulate foreign organisms and destroy them. Leukocytes also produce, transport, and distribute antibodies as part of the immune response to a foreign substance (antigen).

The WBC count serves as a useful guide to the severity of a disease process. Specific patterns of leukocyte response can be expected in various types of diseases as determined by the differential count (showing percentages of each of the different types of leukocytes). Leukocyte and differential counts, by themselves, are of little value as aids to diagnosis unless the results are related to the clinical condition of the patient—only then is a correct and useful interpretation possible. Signs and symptoms of increased WBCs include fever, bruising, petechiae, fatigue, anemia, bleeding of mucous membranes, weight loss, and frequent infections.

Normal Findings ⬆ ⬇

Black adults: 3.2–10.0 × 103 cells/mm3 or × 109/L or 3200–10,000 cells/mm3

Adults: 4.5–10.5 × 103 cells/mm3 or × 109/L or 4500–10,500 cells/mm3

Children:

Clinical Alert

  1. WBC count <500/mm3 or <0.5 × 103/mm3 (or × 109/L) is extremely serious and can be fatal.

  2. WBC count <2.0 × 109/L represents a critical value.

  3. WBC count >30,000/mm3 or >30.0 × 103/mm3 (or × 109/L) is a critical value.

Procedure ⬆ ⬇

  1. Obtain a venous anticoagulated EDTA (lavender-topped tube) whole blood sample of 5 mL or a finger stick sample.

  2. Label the specimen with the patient’s name, date and time of collection, and test(s) ordered.

  3. Blood is processed either manually or automatically, using an electronic counting instrument such as the Coulter Counter® or Abbott CELL-DYN®.

Clinical Implications ⬆ ⬇

  1. Leukocytosis: WBC count >11,000/mm3 or >11.0 × 103/mm3 (or >11 × 109/L)

    1. Leukocytosis is usually caused by an increase of only one type of leukocyte, and it is given the name of the type of cell that shows the main increase:

      1. Neutrophilic leukocytosis or neutrophilia

      2. Lymphocytic leukocytosis or lymphocytosis

      3. Monocytic leukocytosis or monocytosis

      4. Basophilic leukocytosis or basophilia

      5. Eosinophilic leukocytosis or eosinophilia

    2. An increase in circulating leukocytes is rarely caused by a proportional increase in leukocytes of all types. When this does occur, it is usually a result of hemoconcentration.

    3. In certain diseases (e.g., measles, pertussis, sepsis), the increase of leukocytes is so great that the blood picture suggests leukemia. Leukocytosis of a temporary nature (leukemoid reaction) must be distinguished from leukemia. In leukemia, the leukocytosis is chronic and progressive.

    4. Leukocytosis occurs in acute infections, in which the degree of increase of leukocytes depends on severity of the infection, patient’s resistance, patient’s age, and marrow efficiency and reserve.

    5. Other causes of leukocytosis include the following:

      1. Leukemia, myeloproliferative disorders

      2. Trauma or tissue injury (e.g., surgery)

      3. Malignant neoplasms, especially bronchogenic carcinoma

      4. Toxins, uremia, coma, eclampsia, thyroid storm

      5. Drugs, especially ether, chloroform, quinine, epinephrine (adrenaline), colony-stimulating factors

      6. Acute hemolysis

      7. Hemorrhage (acute)

      8. After splenectomy

      9. Polycythemia vera

      10. Tissue necrosis

      11. Sickle cell disease

    6. Occasionally, leukocytosis is found when there is no evidence of clinical disease. Such findings suggest the presence of:

      1. Sunlight, ultraviolet irradiation

      2. Physiologic leukocytosis resulting from excitement, stress, exercise, pain, cold or heat, anesthesia

      3. Nausea, vomiting, seizures

    7. Steroid therapy modifies the leukocyte response.

      1. When corticotropin (adrenocorticotropic hormone [ACTH]) is given to a healthy person, leukocytosis occurs.

      2. When ACTH is given to a patient with severe infection, the infection can spread rapidly without producing the expected leukocytosis; therefore, what would normally be an important sign is obscured.

  2. Leukopenia: WBC count less than 4000/mm3 or less than 4.0 × 103/mm3 or less than 4.0 cells × 109/L occurs during and following:

    1. Viral infections, some bacterial infections, overwhelming bacterial infections

    2. Hypersplenism

    3. Bone marrow depression caused by heavy metal intoxication, toxins, ionizing radiation, drugs:

      1. Antimetabolites

      2. Barbiturates

      3. Benzene

      4. Antibiotic drugs

      5. Antihistamine medications

      6. Anticonvulsants

      7. Antithyroid drugs

      8. Arsenicals

      9. Cancer chemotherapy (causes a decrease in leukocytes; leukocyte count is used as a link to disease)

      10. Cardiovascular drugs

      11. Diuretic drugs

      12. Analgesic and antiinflammatory drugs

    4. Primary bone marrow disorders

      1. Leukemia (aleukemic)

      2. Pernicious anemia

      3. Aplastic anemia

      4. Myelodysplastic syndromes

      5. Congenital disorders

      6. Kostmann syndrome

      7. Reticular agenesis

      8. Cartilage–hair hypoplasia

      9. Shwachman–Diamond syndrome

      10. Chédiak–Higashi syndrome

    5. Immune-associated neutropenia

    6. Marrow-occupying diseases (fungal infection, metastatic tumor)

    7. Pernicious anemia

Interventions ⬆ ⬇

Pretest Patient Care

  1. Explain test purpose and procedure. Assess for signs and symptoms of increased WBCs (e.g., fever, bruising, petechiae, fatigue, anemia, bleeding of mucous membranes, weight loss, history of infections).

  2. Refer to standard pretest care for CBC and differential count. Also, follow guidelines in Chapter 1 for safe, effective, informed pretest care.

  3. Select CBC components ordered at regular intervals (e.g., daily, every other day). These should be drawn consistently at the same time of day for reasons of accurate comparison; natural body rhythms cause fluctuations in laboratory values at certain times of the day.

  4. Dehydration or overhydration can dramatically alter values; for example, large volumes of IV fluids can “dilute” the blood, and values will appear as lower counts. The presence of either of these states should be communicated to the laboratory.

  5. Fasting is not necessary. However, fat-laden meals may alter some test results as a result of lipidemia.

Posttest Patient Care

  1. Review test results; report and record findings. Modify the nursing care plan as needed. Counsel the patient regarding abnormal findings; explain the need for possible follow-up testing and treatment.

  2. Refer to standard posttest care for CBC and differential count. Also, follow guidelines in Chapter 1 for safe, effective, informed posttest care.

  3. In prolonged severe granulocytopenia or pancytopenia:

    • Give no fresh fruits or vegetables because the kitchen, especially in a hospital, may be a source of food contamination.

    • When the WBC count is low, a person can get a bacterial, pseudomonal, or fungal infection from fresh fruits and vegetables.

    • Use a minimal-bacteria or commercially sterile diet. All food must be served from a new or single-serving package.

    • Consider a leukemia diet. See dietary department for restrictions (e.g., cooked food only) and careful food preparation.

    • Do not give intramuscular injections.

    • Do not take rectal temperature, give suppositories, give enemas, or perform rectal examinations.

    • Do not allow patients to floss their teeth.

    • Do not use razor blades.

    • Do not give aspirin or NSAIDs, which cause platelet dysfunction.

    • Observe closely for signs or symptoms of infection; often, patients have only a fever. Without leukocytes to produce inflammation, serious infections can have very subtle findings.

  4. Possible treatments include administration of blood products as ordered, assisting the patient with activities of daily living to decrease fatigue, and close monitoring for signs of infections. Also, provide frequent mouth care and promote hygiene.

Interfering Factors ⬆

  1. Hourly rhythm: There is an early-morning low level and late-afternoon peak. Age, gender, exercise, medications, pregnancy, pain, temperature, altitude, and anesthesia affect test results.

  2. Age: In newborns and infants, the WBC count is high (10,000/mm3–20,000/mm3 or 10 × 109/L–20 × 109/L); the count gradually decreases in children until the adult values are reached between 18 and 21 years of age.

  3. Any stressful situation that leads to an increase in endogenous epinephrine production and a rapid rise in the leukocyte count.