White Blood Cell Disorders Flashcards
1
Q
What is the significance of the white blood cell (WBC) count in the emergency department?
A
The WBC count is one of the most common laboratory tests but has limited sensitivity and specificity for significant infection or disease.
2
Q
What is the most common nonmalignant cause of leukocytosis?
A
Acute infection.
3
Q
Which tests may have more predictive value than the WBC count for bacterial infection?
A
- Procalcitonin
- C-reactive protein (CRP)
4
Q
How should the WBC count be viewed in the acute care setting?
A
As having limited screening value, but useful when combined with history and physical examination findings.
5
Q
What are the three basic cell types in the WBC series?
A
- Granulocytes (neutrophils, eosinophils, basophils)
- Monocytes
- Lymphocytes
6
Q
Where do WBCs reach their site of action?
A
Through the circulation.
7
Q
What is the primary function of the granulocytic series?
A
Phagocytic activity.
8
Q
From where do granulocytes originate?
A
Pluripotential stem cells located in the bone marrow.
9
Q
What is the lifespan of granulocytes once released into circulation?
A
Days.
10
Q
What is the postmitotic storage pool for neutrophils?
A
Contains metamyelocytes, band neutrophils, and mature neutrophils.
11
Q
What happens to the marginal pool of neutrophils during physiological stress?
A
It can rapidly enter the circulating pool, potentially doubling the WBC count.
12
Q
What is indicated by a persistent elevation in WBC count?
A
Possible leukemia or other malignancy.
13
Q
Where do lymphocytes mature?
A
In lymphoid tissues located in the bone marrow, thymus, spleen, and lymph nodes.
14
Q
What are the two types of lymphocytes involved in the immune response?
A
- B cells (humoral immunity)
- T cells (cellular immunity)
15
Q
What is a unique problem in WBC disorders?
A
Wide variability in normal values and multiple influencing factors.
16
Q
How are WBC counts generally performed?
A
Automatically by electrical impedance or optical diffraction techniques.
17
Q
What is a common error in laboratory analysis of WBC counts?
A
Reporting results as percentages instead of absolute counts.
18
Q
What factors can shift the normal WBC count upward?
A
- Exercise
- Female gender
- Smoking
- Pregnancy
19
Q
Which ethnic population tends to have a lower total WBC count?
A
Blacks.
20
Q
What can influence differential counts in laboratory analysis?
A
- Small sample size
- Improper cell identification
- Age group (children)
21
Q
What causes alterations in cell counts?
A
Changes in production, the marginal pool, or the rate of tissue destruction.
These alterations can lead to increased or decreased WBC counts.
22
Q
What are the processes that impact WBC count?
A
Production, destruction, loss, or sequestration.
Each process can lead to either increased or decreased WBC counts.
23
Q
What can cause decreased production of WBCs?
A
Suppression of the bone marrow due to chemotherapy, radiation therapy, or viral infections.
These factors can significantly lower WBC production.
24
Q
What conditions can destroy neutrophils and reduce WBC count?
A
Beta-lactam antibiotics, rheumatoid arthritis, and other autoimmune diseases.
These conditions may lead to neutropenia.
25
What can lead to a net loss of WBCs?
Overwhelming bacterial infections depleting WBCs faster than production.
## Footnote
This can result in a significant drop in circulating WBCs.
26
What is sequestration in the context of WBC disorders?
Sequestration may occur secondary to ischemic reperfusion injury, major trauma, or other tissue insults.
## Footnote
It involves the trapping of WBCs in certain tissues.
27
How should WBC count determinations be interpreted?
In the context of the overall clinical picture.
## Footnote
A careful history and physical examination are critical.
28
What is leukocytosis?
Elevation in WBC count.
## Footnote
Often associated with infection or inflammation.
29
Define neutrophilic leukocytosis (neutrophilia).
An absolute neutrophil count greater than 7500 cells/mm3.
## Footnote
Commonly associated with infection or inflammation.
30
What does a 'left shift' in the differential count indicate?
Movement of immature neutrophils from the postmitotic pool into circulation.
## Footnote
This occurs during infection or inflammation.
31
What factors can increase WBC counts through demargination?
Physiologic stress, endogenous or administered epinephrine, and exercise.
## Footnote
Demargination refers to the release of neutrophils from vessel walls.
32
What is leukopenia?
Any reduction in circulating WBCs.
## Footnote
Often used interchangeably with neutropenia.
33
What is neutropenia?
A reduction of the neutrophil cell line.
## Footnote
It is the most clinically significant form of leukopenia.
34
How is adult neutropenia defined?
An abnormally low absolute neutrophil count (ANC).
## Footnote
ANC is calculated by multiplying the WBC count by the percentage of segmented and band neutrophils.
35
What ANC values are used to classify neutropenia severity?
* Mild: below 1500 cells/mm3
* Moderate: less than 1000 cells/mm3
* Severe: less than 500 cells/mm3
## Footnote
Severe neutropenia increases susceptibility to bacterial infection.
36
What are clinical features of WBC disorders?
Characteristic of the underlying cause, except for hyperleukocytosis.
## Footnote
Hyperleukocytosis can lead to leukostasis.
37
What is hyperleukocytosis?
WBC count greater than 100,000/mm3.
## Footnote
It can result in metabolic abnormalities and multiorgan failure.
38
What symptoms may arise from cerebral involvement in hyperleukocytosis?
* Headache
* Confusion
* Lethargy
* Dizziness
* Blurred vision
* Ataxia
* Papilledema
* Retinal or intracranial hemorrhage
## Footnote
These symptoms are due to microvascular involvement.
39
What pulmonary signs can occur due to hyperleukocytosis?
* Dyspnea
* Tachypnea
* Hypoxia
* Pulmonary infiltrates
* Respiratory failure
## Footnote
These symptoms are related to pulmonary microvascular obstruction.
40
What is leukostasis?
A syndrome characterized by metabolic abnormalities, coagulopathy, and multiorgan failure.
## Footnote
Often arises in the context of hyperleukocytosis.
41
Common Causes
of Leukocytosis
**Primary**
Myeloproliferative disorders: Chronic myeloid leukemia (CML), polycythemia vera
Hereditary neutrophilia
Familial myeloproliferative disease
Chronic idiopathic neutrophilia
Leukemoid reaction
**Secondary**
Infection
Tissue necrosis: Cancer, burns, infarctions
Metabolic disorders: Diabetic ketoacidosis, thyrotoxicosis, uremia
Non-hematologic malignant disease
Physiologic stress: Exercise, pain, surgery, hypoxia, seizures, trauma
Drugs: Epinephrine, corticosteroids, lithium, cocaine
Laboratory error: Automated counters, platelet clumping, precipitated cryoglobulin
Lymphocytosis
Viral infection: Mononucleosis, rubeola, rubella, varicella, toxoplasmosis
Lymphoproliferative: Acute or chronic lymphocytic leukemia (ALL, CLL)
Immunologic response: Immunization, autoimmune diseases, graft rejection
42
What is the average leukocyte count for a 1-week-old infant?
12,200 cells/mm3
## Footnote
Normal range is 5000–21,000 cells/mm3
43
What is the 95% range for leukocyte count in a 6-month-old?
6000–17,500 cells/mm3
## Footnote
Average leukocyte count is 11,900 cells/mm3
44
At what age is the average leukocyte count 11,400 cells/mm3?
12 months
## Footnote
95% range is 6000–17,500 cells/mm3
45
What is the average leukocyte count for a 4-year-old?
9100 cells/mm3
## Footnote
Normal range is 5500–15,500 cells/mm3
46
What is the normal leukocyte count range for an 8-year-old?
4500–13,500 cells/mm3
## Footnote
Average leukocyte count is 8300 cells/mm3
47
What is the average leukocyte count for adults?
7400 cells/mm3
## Footnote
Normal range is 4500–11,000 cells/mm3
48
Fill in the blank: The normal leukocyte count range for a 1-week-old is _______.
5000–21,000 cells/mm3
## Footnote
Average leukocyte count is 12,200 cells/mm3
49
True or False: The average leukocyte count decreases with age.
True
## Footnote
Average counts decrease from infancy to adulthood.
50
What are the clinical features of WBC disorders?
Clinical features often reflect the underlying cause of the WBC disorder
## Footnote
For example, leukocytosis may show characteristics of the inciting infection.
51
What is hyperleukocytosis?
WBC >100,000/mm3, leading to leukostasis characterized by metabolic abnormalities, coagulopathy, and multiorgan failure.
52
What organ systems are most often affected by hyperleukocytosis?
Cerebral, pulmonary, or renal microvasculature.
53
What are common CNS signs and symptoms of hyperleukocytosis?
* Headache
* Confusion
* Lethargy
* Dizziness
* Blurred vision
* Ataxia
* Papilledema
* Retinal or intracranial hemorrhage
54
What pulmonary signs and symptoms may occur due to hyperleukocytosis?
* Dyspnea
* Tachypnea
* Hypoxia
* Pulmonary infiltrates
* Respiratory failure
55
What complications can arise from mechanical obstruction of capillaries due to hyperleukocytosis?
* Peripheral vascular occlusion
* Acute renal failure
* Myocardial infarction
56
What are the primary causes of leukocytosis?
* Myeloproliferative disorders
* Hereditary leukocytosis
* Congenital anomalies
* Leukemoid reaction
57
What is a leukemoid reaction?
A pronounced leukocytosis associated with acute inflammation or infection that may be mistaken for leukemia.
58
What is the most common form of leukocytosis?
Secondary forms of leukocytosis.
59
What diagnostic test is often used to identify WBC disorders?
Complete blood count (CBC).
60
What may the presence of pancytopenia indicate?
Aplastic anemia and bone marrow failure due to various causes.
61
What additional laboratory tests may aid in evaluating a WBC disorder?
* Peripheral blood smear
* Sedimentation rate
* CRP
62
What does a peripheral blood smear help identify?
Abnormal cell morphology.
63
What does elevation of the ESR or CRP indicate?
Occult infection and may guide initiation of antimicrobial treatment.
64
What imaging studies are indicated in the setting of hyperleukocytosis?
* Chest radiograph
* Neurologic imaging
65
What is the role of immature granulocytes (IG) measurements?
Identifying patients with severe sepsis and other diseases associated with systemic inflammatory response syndrome.
66
What is the management approach for most WBC disorders?
Related to the underlying disease process.
67
What is the management for hyperleukocytosis?
Lower the WBC as rapidly as possible using chemotherapy or leukapheresis.
68
What may rapid reduction of WBC with chemotherapy induce?
Tumor lysis syndrome.
69
Who should make decisions regarding chemotherapy and leukapheresis?
A hematologist.
70
Why is leukapheresis often the therapeutic modality of choice in hyperleukocytosis?
Associated with a high mortality rate when pulmonary or CNS clinical features are present.
71
What does patient disposition in WBC disorders depend on?
Type and severity of the underlying cause.
72
What percentage of newly diagnosed adult leukemia cases does Chronic Myeloid Leukemia (CML) account for?
Approximately 10% to 15%.
73
What genetic aberration is commonly associated with CML?
Philadelphia chromosome.
74
Is the mutation associated with CML inherited?
No, the mutation is not inherited.
75
What is the median age of diagnosis for CML?
Between 57 and 60 years.
76
What are the three phases of CML progression in the absence of effective treatment?
* Chronic
* Accelerated
* Blastic
77
What is a common feature of the peripheral blood smear in the chronic phase of CML?
Leukocytosis with immature myelocytes, metamyelocytes, band cells, and mature polymorphonuclear leukocytes.
78
What is the blastic crisis in CML?
The sudden appearance of an acute form of leukemia associated with poor outcomes.
79
What are common presenting features in symptomatic CML patients?
* Abdominal pain
* Decreased appetite
* Nausea
* Early satiety
* Fatigue
* Weight loss
* Diaphoresis
* Low-grade fevers
80
What laboratory abnormalities are associated with CML?
* Decreased leukocyte alkaline phosphatase
* Increased vitamin B12 levels
81
What are the indications for urgent therapy in CML?
* Hyperuricemia and renal injury
* Severe anemia and subsequent angina or heart failure
82
What is lymphocytic leukocytosis (lymphocytosis) defined as in adults?
Greater than 5000 cells/mm3.
83
What is the most common type of leukemia seen in individuals aged 50 years or older?
Chronic lymphocytic leukemia (CLL).
84
What is the median age of diagnosis for CLL?
72 years.
85
What type of cells primarily characterize CLL?
Mature B lymphocytes.
86
What is the most common cancer diagnosed in children?
Acute lymphocytic leukemia (ALL).
87
What is a common symptom associated with CLL?
Fatigue and malaise.
88
What diagnostic testing confirms the diagnosis of CLL?
Monoclonal determination of B cells through flow cytometry or molecular assays.
89
What treatment options exist for CLL?
* Chemotherapy agents
* Monoclonal antibodies
* Allogenic stem cell transplantation
90
What is the prognosis for adult ALL compared to pediatric ALL?
Adult ALL has a much poorer prognosis with complete remission rates of only 20% to 40%.
91
What factors influence decision making regarding transplant therapy in leukemia patients?
* Patient age
* Comorbidities
* Disease subtype
* Genetics
* Response to therapy
92
What is the typical clinical course of most CLL patients?
Indolent, requiring either no treatment or delayed treatment.
93
What is the risk associated with leukostasis in ALL?
Increases when the blast count rises above 50,000 cells/mm3.
94
What are common signs of CLL at diagnosis?
* Abnormal WBC count
* Enlarged lymph nodes
* Palpable spleen
* Enlarged liver
95
What is the role of tyrosine kinase inhibitors in CML management?
They target proteins resulting from the Philadelphia chromosome genetic anomaly.
96
Fill in the blank: Chronic lymphocytic leukemia (CLL) is primarily a _______ disorder.
B-cell
97
What is the broad definition of leukopenia?
Any reduction in the circulating WBCs.
98
How is the term leukopenia often used interchangeably?
With neutropenia, which refers specifically to a reduction of the neutrophil cell line.
99
What is defined as adult neutropenia?
An abnormally low absolute neutrophil count (ANC).
100
How is the ANC calculated?
By multiplying the WBC count by the combined percentage of segmented and band neutrophils.
101
What ANC value is considered mild neutropenia?
Below 1500 cells/mm3.
102
What ANC value is considered moderate neutropenia?
Less than 1000 cells/mm3.
103
What ANC value is considered severe neutropenia?
Less than 500 cells/mm3.
104
What is a well-known risk factor for increased susceptibility to bacterial infection?
Severe neutropenia.
105
What can cause neutropenia?
Decreased production, impaired maturation, movement into marginal or tissue pools, increased destruction, or laboratory error.
106
What common infectious etiologies can cause neutropenia in adults?
* HIV * EBV * Hepatitis * Parasitic infections (e.g., malaria) * Bacterial sepsis.
107
What is the most common cause of acquired neutropenia in children?
Viral infection.
108
What are the nonspecific signs and symptoms of neutropenia?
* Fatigue * Sweats * Weight loss.
109
What is neutropenic fever defined as?
A single oral temperature ≥ 101°F (38.3°C) in a neutropenic patient.
110
What should be done when a neutropenic patient develops fever?
Initiate a rapid workup and commonly administer broad-spectrum antibiotics.
111
What percentage of patients receiving chemotherapy develop neutropenic fever?
Up to 80%.
112
What should the evaluation focus on for neutropenic fever?
Identifying any infectious agents.
113
What are common locations to investigate for infections in neutropenic patients?
* Lungs * Urine * Bloodstream.
114
What is evolving regarding the disposition of febrile neutropenic patients?
Carefully selected patients may be eligible for discharge following ED evaluation.
115
What factors may allow for outpatient therapy in febrile neutropenic patients?
No significant comorbidities or signs of sepsis, and reliable follow-up plans.
116
When should septic patients be hospitalized?
They will require hospitalization and neutropenic isolation precautions.
117
What can be arranged for asymptomatic patients with incidental neutropenia?
Follow-up, which may include further investigation.
118
Fill in the blank: Neutropenia increases susceptibility to _______.
[overwhelming infection]
119
Linkage of Leukopenia
to Phases of Neutrophil Maturation
**Mechanism / Example**
-Proliferation in bone marrow
Aplastic anemia, leukemia, cancer chemotherapy (cyclophosphamide, azathioprine, methotrexate, chlorambucil)
Drugs: Phenothiazines, phenylbutazone, indomethacin, propylthiouracil, phenytoin,
cimetidine, semisynthetic penicillins, sulfonamides
Infection: Viral, tuberculosis, sepsis
- Maturation in bone marrow
Folate or vitamin B12 deficiency, chronic idiopathic neutropenia
Starvation
- Distribution
Hypersplenism: Sarcoidosis, portal hypertension, malaria
- Increased use
Infection: Viral most common (mononucleosis, rubella, rubeola), Rickettsia organisms, overwhelming bacterial infection
Autoimmune disease: Systemic lupus erythematosus, AIDS, Felty syndrome
- Laboratory error
Leukocyte clumping, long delay in performing test
