Lab Test: White Blood Cell Count, WBC

With rates of pneumococcal disease continuing to fall due to the release of the heptavalent pneumococcal vaccine, the expectation is that this test will continue to have even lower utility. The value of this test does not appear to be affected by the stress imposed by the length of the seizure.

Hantavirus pulmonary syndrome

The WBC count is typically >12,000/mm3, with a median peak cell count of 26,000/mm3 during hospitalization. The combination of a maximally increased WBC count and partial thromboplastin time (PTT) are predictive of death.

Some patients with hantavirus pulmonary syndrome may present with leukopenia (WBC <4,000/mm3).

Hemolytic uremic syndrome (HUS)

Leukocytosis is usually present, with a mild to moderate left shift and a number of immature cells. The mean WBC count is approximately 17,000/mm3 and may be as high as 48,500/mm3.

It is uncertain whether the inflammatory response represents a marker of severity of the Escherichia coli O157:H7 gastrointestinal infection or whether it is a pathophysiologic marker that leads to hemolytic uremic syndrome (HUS).
An elevated polymorphonuclear leukocyte count (particularly >15,000/mm3) on admission is predictive of severe disease and poor prognosis in patients with HUS.

Hospitalized patients with community-acquired pneumonia or children with suspected pneumonia

for bacterial pneumonia, a WBC count of 10,000 to 14,000/mm3 with a marked left shift is typical. A WBC count >15,000/mm3 strongly suggests a bacterial, particularly a pneumococcal, etiology. A WBC count >20,000/mm3 is associated with a poor prognosis.

In atypical pneumonia, the WBC count usually is only minimally elevated, although in severe cases, counts of 20,000 to 30,000/mm3 may be present.
In Legionnaires disease, a moderately high leukocytosis with a left shift is present in 50% to 80% of patients. This feature may help differentiate Legionella from other causes of atypical pneumonia.
A WBC count of 20,000/mm3 or greater in febrile children may indicate an occult pneumonia.
A lack of systemic inflammatory response (i.e., absence of fever and leukocytosis) is associated with significantly increased mortality in elderly patients with pneumonia.
Immunosuppressed or elderly patients with overwhelming infection may present with leukopenia and a left shift.
In male patients with bacteremic community-acquired lobar pneumonia, the presence of leukopenia is more suggestive of Klebsiella than of pneumococcal pneumonia.
Early in the course of severe acute respiratory syndrome (SARS), the absolute lymphocyte count is often decreased. Overall WBC counts have generally been normal or decreased.

Initial evaluation of suspected diabetic ketoacidosis (DKA)

An elevated WBC count in DKA may be due to stress and dehydration, and should not be interpreted as a sign of infection.
The majority of patients with DKA present with leukocytosis proportional to the blood ketone body concentrations. The majority of patients in suspected DKA present with WBC counts in the 10,000/mm3 to 15,000/mm3 range without a left shift.
A count >25,000/mm3 with a left shift suggest bacterial infection.

Initial evaluation of suspected hyperglycemic hyperosmolar state (HHS)

The majority of patients with HHS present with leukocytosis proportional to the blood ketone body concentration.
The majority of patients present with WBC counts in the 10,000 to 15,000/mm3 range without a left shift; counts >25,000/mm3 with a left shift suggest bacterial infection.

Known or suspected hematological malignancies

Patients with primary bone marrow disorders (e.g., leukemia or myeloproliferative disorders) often preset with extreme leukocytosis.

In acute myelogenous leukemia (AML), WBC counts are usually above 15,000/microL and maybe as high as 1 million cells/mm3; rarely, neutropenia is observed. Fewer than 15% of patients have WBC counts <100,000 cells/microL. These findings are usually associated with anemia and thrombocytopenia.
In chronic myelogenous leukemia (CML), a WBC count between 30,000 and 400,000/microL is frequently seen, associated with thrombocytosis, mild-to-moderate anemia, and splenomegaly. Hyperleukocytosis at the time of diagnosis is most frequently seen in patients with CML.
In patients with myelogenous or lymphocytic leukemia, signs of pulmonary infiltration (dyspnea, tachypnea, and hypoxia) may be associated with high blast cell counts (WBC counts above 100,000 cells/microL).
Hyperleukocytosis may cause complications arising from leukostasis in cerebral or pulmonary capillary beds. Headache=, priapism, blurred vision, and other neurologic symptoms have also been associated with a high blast cell count.

Chronic lymphocytic leukemia

WBC counts are usually >20,000 cells/microL.

Metabolic acidosis

The WBC count is frequently elevated and is probably a nonspecific effect of acidosis. This response may be caused by catecholamine-induced WBC margination.

A marked leukocytosis (WBC count 24,000 to 65,000/mm3) may be seen in cases of significant paraldehyde intoxication.
When leukemia or lymphoma are predisposing factors for lactic acid production, a high WBC count may be seen.

Schizophrenia

hematological effects, including inhibition of leucopoiesis, can occur with the use of clozapine or first-generation antipsychotic medications. During clozapine treatment, WBC counts should remain above 3000/mm3 and absolute neutrophil counts (ANC) should remain above 1500/mm3.

If the WBC drops below 2,000/mm3 or the ANC drops to 1000/mm3, the medication must be stopped immediately and the patient monitored for the infection, with daily che4cks of blood cell counts.
If the WBC drops to 2,000 to 3,000/mm3 or the ANC drops to 1,000 to 1,500/mm3, the medication should be stopped immediately and the patient monitored for infection with daily checks of blood cell counts. Clozapine may be resumed when the patient's WBC is >3,000 or the ANC is >1,500 and there are no signs of infection. Counts should be done biweekly until the WBC is >3,500.
If the WBC is between 3,000 and 3,500/mm3 or if the WBC has dropped to 3,000/mm3 over 1 to 3 weeks, or if immature cell forms are present, the count should be repeated. If the WBC remains between 3,000 and 3,500/mm3 and the ANC is >1,500/mm3, the counts should be monitored, with a differential, bi-weekly until the WBC is>3,500/mm3. If the counts drop below 3,000/mm3, or the ANC is below 1,500/mm3, the guidelines listed above should be followed.
For patients treated with clozapine, the risk for hematological effects is highest in the first 6 months.

Suspected abruption placentae

The WBC count is usually normal but may be slightly increased. With marked elevation of the WBC count, other causes of abdominal pain (e.g., appendicitis) should be considered. In pregnant trauma patients, an elevated WBC count on admission (>20,000/mm3) is an indicator of ongoing placental abruption and requires close monitoring.

Suspected acute mesenteric ischemia

Leukocytosis (WBC count ≥15,000/mm3) is common in the acute setting of bowel ischemia, but neither its presence nor the degree of WBC elevation is helpful in diagnosis. WBC count is normal in about 15% of cases.

Suspected adrenal insufficiency

The total WBC count is usually >10,000/mm3 in adrenal crisis; however, it also may be normal. In chronic adrenal insufficiency, the total WBC count may be <5,000/mm3.

Lymphocytosis

A relative lymphocytosis is common in chronic adrenal insufficiency. Cortisol is necessary for the maintenance of the reticuloendothelial system and normal lymphoid tissue. In the absence of cortisol, lymphocytic infiltration of body tissues has been noted. This finding may also be seen in adrenal crisis, but a nonspecific leukocytosis is more common.

Suspected and known avian influenza

Leukopenia is a common finding. In one series, the median total leukocyte count was 2,109 (range 1,200 to 3,400/mm3), with a marked inversion of the CD4:CD8 ratio noted in some patients.

A decreased leukocyte count is associated with the development of acute respiratory distress syndrome (ARDS) and an increased risk of death.
Lymphopenia is a common finding in avian influenza. In one series, the median total lymphocyte count was 700 (range 250 to 1,100/mm3). Lymphopenia is associated with the development of ARDS and an increased risk of death.

Suspected and known blunt abdominal trauma

Elevations of the WBC count to 20,000/mm3 with a moderate left shift occur frequently within several hours of injury and persist for several days. The elevation is the result of stress-caused demargination, tissue injury, acute hemorrhage, and peritoneal irritation.

Suspected and known Kawasaki disease

The peripheral WBC count is often >15,000/mm3 with a left shift in acute Kawasaki disease. A high toxic neutrophil (peripheral neutrophils with vacuoles and/or toxic granulations) count has been associated with Kawasaki disease.

Increases in WBC and neutrophil counts after intravenous immunoglobulin (IVIG) therapy have been associated with coronary artery aneurysms and may suggest the need for more aggressive treatment.

Suspected and known mastoiditis

The WBC count is >15,000/mm3 in the majority of patients.

Suspected and known septic bursitis

Leukocytosis is not diagnostic of septic bursitis since it is present in only 30% to 40% of the patients and may occur in other inflammatory process such as gout.

WBC counts have been found to range from 3,700 to 24,400/mm3 (mean 11,000 to 12,000/mm3) in septic bursitis with increases in the band forms more frequent among immunocompromised patients.
Serial peripheral WBC counts, if initially elevated, may be a useful laboratory measurement to substantiate clinical improvement with treatment, although more specific indices of treatment effectiveness are conversion of the bursal fluid cultures from positive to negative and reduction in bursal fluid leukocyte concentration.

Suspected appendicitis

Although leukocytosis is more common in patients with appendicitis that those without, the WBC count may be normal early in the course in nearly 25% of the patients with appendicitis.

Acute appendicitis is unlikely in the setting of a normal leukocyte count and C-reactive protein; however, the WBC count should never be used alone to diagnose appendicitis and determine patient disposition, although serial levels may be helpful in equivocal cases.
Although the presence of leukocytosis may suggest the diagnosis of appendicitis, racial differences, early normal values, and the inability to differentiate appendicitis from other causes of abdominal pain limits its usefulness as a reliable diagnostic marker.
Blacks tend to have a significantly lower WBC count in acute appendicitis that do whites.
The WBC count may be elevated in patients with a normal appendix.
Leukocytosis is noted in 70% to 90% of cases; it is usually mild to moderate (10,000 to 18,000/mm3), with polymorphonuclear predominance. A marked elevation >18,000 to 20,000/mm3 suggests rupture, phlegmon, or abscess.
In children, the WBC count with differential is the single most useful laboratory test but is helpful only in supporting the clinical diagnosis; bot the total count and percentage of neutrophils are significantly higher in appendicitis.
Appendicitis should be suspected in pregnant patients with abdominal pain and a WBC count >12.5 x 10⁹/L. especially if associated with nausea and abdominal guarding.
In patients older than 60 years, an elevated WBC count or abnormal differential is the most valuable laboratory test. In one study, 80% of patients had WBC counts >10,000/mm3; 12% had only a left shift (greater than 10 bands) noted.

Suspected bacterial infection

Leukocytosis (WBC count>12,000 cells/mm3), and in particular Neutrophilia, is a characteristic sign of systemic inflammation in response to infection.

In the context of meningitis, the majority of patients have a WBC count >10,000/mm3; however, the peripheral WBC count is not a useful screening test for ruling out meningeal infection, nor should it be used for the purpose of identifying infants in need of diagnostic lumbar puncture.
When combined with 3 other clinical markers (urinary analysis, age, and temperature), elevated WBC count was found to be predictive of serious bacterial infection in infants less than 3 months of age.
Leukopenia (WBC count <4,000/mm3) is a possible sign of systemic inflammation in response to infection. It may be seen in immunosuppressed or debilitated patients, as well as in patients with overwhelming sepsis.

Suspected bowel obstruction

The WBC count is inconsistently elevated with a bowel obstruction. However, it may signify bowel perforation or strangulation. The absence of leukocytosis does not rule out bowel obstruction or strangulation.

Suspected cholecystitis

The WBC count is elevated in 85% of patients with acute cholecystitis. Like fever, it is not a reliable indicator in the elderly or immunocompromised patient.

In cholecystitis, the WBC count may be increased to 12,000 to 15,000/mm3, with a left shift toward neutrophils and band forms. Retrospective chart reviews of pathologically confirmed acute cholecystitis found WBC counts <11,000/mm3 in 25% to 40% of cases.

Suspected choledocholithiasis

Combined elevations of the WBC count, alkaline phosphatase, and total bilirubin suggest choledocholithiasis and herald acute toxic cholangitis.

Suspected disseminated gonococcal infection (DGI or gonococcemia)

The WBC may be increased to 12,000/mm3 with gonococcal arthritis and may reach as high as 17,500/mm3 during the bacteremic phase of disseminated gonococcal infection.

Suspected diverticulitis

Leukocytosis is present in over 80% of patients.
The WBC count may be normal in half to two thirds of patients with acute complications from diverticulitis at surgery.
The absence of leukocytosis does not rule out the diagnosis of diverticulitis.

Suspected epididymitis

A WBC count >10,000/mm3 was present in 4 of 8 men over the age of 30 with testicular torsion, 3 of whom were initially diagnosed as having epididymitis.
In 25 patients with epididymitis under 18 years of age, only 44% had WBC counts >10,000/mm3.

Suspected epiglottitis after the airway is secured

Although the WBC count may be decreased, normal, or increased, most patients will have a WBC count >10,000/mm3.

Elevated WBC and tachycardia correlate significantly with airway compromise in adults. Leukocytosis with a left shift in the differential may be seen.

Suspected erysipelas

Nearly all of these patients have leukocytosis and an elevated erythrocyte sedimentation rate or CV-reactive protein, but these findings are nonspecific.

Leukocytosis, that is, a WBC of 10,000 to 20,000/mm3, is characteristic, but nonspecific for the diagnosis.

Suspected esophageal perforation

The WBC count is usually elevated (as reported in 15% to 60% of patients with esophageal perforation); the differential count usually demonstrates a shift to the left.

The WBC count typically doubles within 2 to 6 hours of the injury, making it a reliable early indicator of injury.

Suspected gout

The serum WBC count is elevated in acute gout, but levels are typically not as high as levels seen in septic arthritis.
Mild leukocytosis occurs in acute gout attacks, but the WBC count may be as high as 25, 000/mm3.

Suspected hyperventilation

The WBC is usually normal. When WBC is elevated, causes other than hyperventilation syndrome (HVS) should be sought, including pneumonia, myocardial infarction, or pulmonary infarction. A patient with HVS may be in a hyperadrenergic state, which may elevate the WBC count secondary to demargination.

Suspected hypothermia

Decreased white blood cells may occur from splenic, hepatic, or splanchnic sequestration. Leukopenia does not imply an absence of infection.
It is a common finding in patients who are at either age extreme, intoxicated, myxedematous, debilitated, or who have secondary hypothermia.
An increased WBC count is common in neonated hypothermia and also may occur with associated leukemia, infections, or water depletion.

Suspected infective endocarditis

A WBC count of 10,000 to 20,000/mm3 may be present, but it is commonly normal or ay even be low. A leukocyte count of >10,000/mm3 is present in about 50% of patients, and occurs more commonly when embolic complications of acute infective endocarditis are present, or when infections are due to organisms other than S viridans.

Leukopenia is uncommon (5% to 15%) and, when present, usually is associated with splenomegaly.

Suspected inhalation anthrax

On initial presentation, the total WBC count may be normal or slightly elevated, however, elevation in the percentage of neutrophils with prominent band forms is frequently noted.

Suspected Ludwig's angina

Leukocytosis >10,000/mm3 is present in about 85% of patients.
This is considered a medical emergency

Suspected mumps

A polymorphonuclear leukocytosis (WBC count of 15,000 to 20,000.mm3) is common with extraparotid manifestations of mumps, particularly meningitis, orchitis, or pancreatitis.

Suspected necrotizing soft tissue infection

In one series of necrotizing soft tissue infections, the WBC count was elevated in all patients except those with synergistic gangrene, with an average of 17,303/mm3. An admission WBC >15,400/mm3 combined with a serum Na <135 mmol/L may help distinguish necrotizing fasciitis from non-necrotizing fasciitis, particularly when classic "hard" signs of necrotizing fasciitis such as hypotension, crepitation, skin necrosis, bullae, or gas on x-ray are absent. A WBC count >30,000/mm3 upon admission is an objective predictor of increased mortality in patients diagnosed with necrotizing fasciitis.

The peripheral WBC count may be depressed in overwhelming wound infections, especially in patients diagnosed with clostridial myonecrosis.
A WBC count <4000/mm3 with greater than 10% bands is predictive of an ominous course. The WBC count should be taken in context with the clinical index of suspicion. An elevated WBC count is consistent with the diagnosis of necrotizing soft tissue infection, whereas a lower WBC count suggests a lower likelihood of the disease.

Suspected neonatal sepsis

WBC counts >21,000/mm3 or <5,000/mm3 may be an effective means of detecting sepsis in neonates less than 30 days old. The ability to predict sepsis may be enhanced by combining the WBC count with other CBC-associated measures of inflammation.

Suspected neuroleptic malignant syndrome (NMS)

A WBC count of 12,000 to 30,00/mm3 with or without a left shift is characteristic of NMS, although it is a nonspecific finding.
WBC count does not help to differentiate NMS from NMS-like acute medical illnesses, in particular sepsis.

Suspected or known aspiration pneumonitis

Although there is usually an elevation in the WBC count, this is not a helpful finding in the initial diagnosis.
Leukocytosis (WBC count >10,000/mm3) 2 to 3 days after an apparent recovery from aspiration indicates a probable secondary bacterial infection.

Suspected or known myocardial infarction

WBCs may be elevated secondary to stress and increased catecholamine production in shock. Leukocytosis (WBC 12,000 to 15,000/mm3) during the first few hours of myocardial infarction is common. Greater increases often will be noted when large areas of cardiac necrosis are present or when complications occur.

Leukocytosis may be a response to tissue necrosis, increases secretion of adrenal glucocorticoids, or both.

Suspected or known respiratory failure

An increased WBC count may signal infections as the precipitating factor or it may represent an acute stress reaction from any cause.

A decreased WBC count, especially neutropenia (WBC count <3,000/mm3), may indicate overwhelming infection, especially in the elderly.
A left shift with increased band forms, toxic granulations, or Dohle bodies makes the diagnosis of a coexistent infection more likely.

Suspected or known status epilepticus

The usual range of the WBC count is 12,000-28,000/mm3, even without evidence of infection.
A high WBC count with elevated bands may indicate an underlying infection; however, an elevated WBC level without an increase in band forms is a response to physiologic stress and is often seen in patients with status epilepticus.

Suspected pancreatitis

The WBC count is often elevated (10,000 to 30,000/mm3).
Marked leukocytosis or persistent elevation after therapy should alert the clinician to a possible abscess.

Suspected pelvic inflammatory disease (PID)

Fewer than 50% of patients have a WBC count >12,000/mm3; however, most will exhibit a left shift (increased ratio of band to segmented forms). In some cases, the WBC count may be increased up to 20,000/mm3.

Gonococcal PID is associated with a higher WBC count than is chlamydial PID.

Suspected peritonsillar abscess

The WBC count will be elevated with a shift to the left in approximately 80% of patients, but it may not be helpful in distinguishing peritonsillar abscess from cellulitis.

Suspected post-streptococcal glomerulonephritis

The WBC count is mildly elevated with a polymorphonuclear neutrophil shift to the left, in those patients who present during or soon after a streptococcal infection.

Suspected pulmonary embolism

The WBC count may range from normal to 15,000 to 20,000/mm3, with higher values possibly suggesting infarction.

Suspected septic arthritis

Although the WBC count is elevated in up to 90% of patients with septic arthritis, this finding is an unreliable marker of septic arthritis.

A WBC count >11,000/mm3 has a poor sensitivity in predicting septic arthritis. The WBC count is extremely variable in adults with bacterial arthritis. Laboratory tests do not rule out septic arthritis with any degree of accuracy.
Gonococcal arthritis is more likely to be accompanied by a normal WBC count than is septic arthritis caused by other organisms.
Retrospective and prospective studies have found that an elevated WBC count should not be used to differentiate between septic arthritis of the hip and other more benign causes of hip pain in children.

Suspected Stevens-Johnson syndrome

A WBC count <9,000/mm3 is a common finding, noted within 72 hours of the appearance of skin lesions. The presence of leukopenia significantly increases the risk of sepsis.

Leukocytosis is present in about 25% of patients with this syndrome.

Suspected subarachnoid hemorrhage

An admission WBC count >20,000/mm3 in spontaneous subarachnoid hemorrhage correlates with a poor clinical grade and poor prognosis (50% morbidity).

A WBC count >15,000/mm3 is significantly associated with increased risk of cerebral vasospasm following spontaneous subarachnoid hemorrhage.

Suspected testicular torsion

A normal WBC count is suggestive of testicular torsion, but not diagnostic.

Leukocytosis does not exclude the diagnosis of acute testicular torsion because 33% to 67% of patients with this have an elevated WBC count.

Suspected torsion of the ovary, ovarian pedicle, or fallopian tube

Generally the WBC count is normal or only mildly elevated to >15,000/mm3 in about 20% of cases. A shift to the left may also be noted.

Suspected toxic epidermal necrolysis

A WBC count <9,000/mm3 is a common finding, noted within 72 hours of the appearance of skin lesions, most typically being a Lymphopenia. The presence of leukopenia significantly increases the risk of sepsis.

In one study, a lower nadir in the WBC count in patients with toxic epidermal necrolysis was significantly associated with a fatal outcome.
Leukocytosis is present in approximately 25% of patients.

Suspected toxic shock syndrome

Varying degrees of leukocytosis are present. Leukopenia may be present in streptococcal toxic shock syndrome.

A left shift to immature forms of neutrophils is common in toxic shock syndrome.

Suspected tularemia

The WBC count may be elevated to 24,000.mm3 (mean 11,000/mm3), regardless of clinical syndrome.

The WBC count is normal in uncomplicated cases, and is often normal in toxic-appearing patients despite a high fever.

Clinical Application

The WBC count has two components.

The first is a count of the total number of WBCs (leukocytes) in 1 mm3 of peripheral venous blood.
The other component, the differential count, measures the percentage of each type of leukocyte present in the same specimen.

An increase in the percentage of one type of leukocyte means a decrease in the percentage of another.
Neutrophils and lymphocytes make up 75% to 90% of the total leukocytes. These leukocyte types can be identified easily by their morphology on a peripheral blood smear or by automated counters.
The total leukocyte count has a wide range of normal values but many diseases may induce abnormal values.
An increased total WBC count (leukocytosis, WBC count >10,000) usually indicates infection, inflammation, tissue necrosis, or leukemic neoplasia.
Trauma or stress, either emotional or physical, may increase the WBC count.
In some infections, especially sepsis, the WBC count may be extremely high and reach levels associated with leukemia. This is called a "leukemoid" reaction and quickly resolves as the infection is successfully treated. The major function of WBCs is to fight infection and react against foreign bodies or tissues.
Five types of WBCs may easily be identified on a routine blood smear. These cells, in order of frequency, include neutrophils, lymphocytes, monocytes, eosinophils, and basophils.
The WBC is routinely measured as part of the complete blood cell count. Serial WBC counts have both diagnostic and prognostic values.
Increased WBC count (leukocytosis) may indicate:

Infection, leukemic neoplasia or other myeloproliferative disorders, other malignancy, trauma, stress, or hemorrhage, tissue necrosis, inflammation, dehydration, thyroid storm, or steroid use

Decreased WBC count (leukopenia) may indicate:

Drug toxicity (e.g., cytotoxic chemotherapy or other drugs that decrease the WBC count), bone marrow failure overwhelming infections, dietary deficiency (e.g., vitamin B12, iron deficiency), congenital marrow aplasia, bone marrow infiltration (e.g., myelofibrosis), autoimmune disease, or hypersplenism

Related Tests

Complete blood count

Lymphocyte immunophenotyping - used to detect the progressive depletion of CD4 T lymphocytes, which is associated with an increased likelihood of clinical complications from acquired immunodeficiency syndrome (AIDS). Test results can indicate if an AIDS patient is at risk for developing opportunistic infections.

Peripheral blood smear - a direct microscopic analysis of the cellular components of the blood

Drug-Lab Interactions

Eating, physical activity, and stress may cause an increased WBC count and alter the differential values.

Pregnancy (final month) and labor may be associated with increased WBC levels.

Patients who have had a splenectomy have a persistent mild to moderate elevation of WBC counts.

The WBC count tends to be lower in the morning and higher in the late afternoon.

The WBC count tends to be age related. Normal newborns and infants tend to have higher WBC counts than adults. It is not uncommon for the elderly to fail to respond to infection by the absence of leukocytosis. In fact, the elderly may not develop an increased WBC count even in the face of a severe bacterial infection.

Drugs that may cause increased WBC levels include: adrenaline, allopurinol, aspirin, chloroform, epinephrine, heparin, quinine, steroids, and triamterene (Dyrenium).

Drugs that may cause decreased WBC levels include: antibiotics, anticonvulsants, antihistamines, antimetabolites, antithyroid drugs, arsenicals, barbiturates, chemotherapeutic agents, diuretics, and sulfonamides.

Test Tube Needed

Lavender (EDTA) or red top tube

Procedure

Collect a venous blood sample.

Apply pressure or a pressure dressing to the venipuncture site and assess the site for bleeding.

Avoid use of heparin.

Storage and Handling

May be stored for 24 hours at 23°C and for 48 hours at 4°C.

What To Tell Patient Before & After

Explain the procedure to the patient.

Tell the patient that no fasting is required.

References

Clin Lab Med 2015;35:11-24.
Briggs C et al. Int J Lab Hematol 2014;36:613-627.
Mayo Clin Proc 2005;80:923-936.
LaGow B et al., eds. PDR Lab Advisor. A Comprehensive Point-of-Care Guide for Over 600 Lab Tests. First ed. Montvale, NJ: Thomson PDR; 2007.

Pagana K, Pagana TJ eds. Mosby's Manual of Diagnostic and Laboratory Tests. 5^th Ed. St. Louis, Missouri. 2014.

MESH Terms & Keywords
White Blood Cell Count, WBC, White Count, WBC Lab Test, Leukocytes

Submit a Comment Submit a Topic How to Expand Ref How to Search

	All
	Keyphrases
	Article Title
	Article Content

	Anatomy Images		Biostatistics
	Calculators		Clinical Trials
	Differential Diagnosis		Drug Reference
	EBM Topics		Lab Tests
	Pharmacogenetics		Pharmacology
	Physical Exam		Practice Area
	Procedures		Radiology
	Reference Tools		Toxicology

	All of the Words
	Any of the Words
	Exact Phrase

Lab Test: White Blood Cell Count, WBC 1

Lab Test: White Blood Cell Count, WBC

MESH Terms & Keywords