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Lab Medicine > CBC > Flashcards

CBC Flashcards

1
Q

Components of CBC with Differential

A 
White blood cell count and differential count
Red blood cell count
Red Blood cell indices
Hemoglobin
Hematocrit
Platelet count
Mean platelet volume
Peripheral blood smear (if indicated)
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2
Q

What does CBC stand for

A

Complete blood count

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3
Q

Indications for CBC

A

Used for screening when abnormalities in RBCs, WBCs, or platelets are suspected
Evaluating symptoms - weakness, fatigue, fever, bruising
Diagnosing condition - anemia, infection, leukemia
Determine stages of a disease

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4
Q

White Blood cell Count - normal values, useful for?

A

adults and kid > 2 years: 5,000-10,000/mm3. kids < 2 and newborns 17,000 and 30,000
Part of all routine lab diagnostic evaluation. Helpful in evaluating a patient with infection, neoplasm allergy, or immunosuppression

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5
Q

WBC > 10,000 indicates?

A

infection, inflammation, tissue necrosis, or leukemic neoplasm.

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6
Q

What is a leukemoid reaction?

A

In sepsis, the WBC count may be extremely high and reach levels similar to leukemia – this is called a leukemoid reaction and resolves as the infection is treated

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7
Q

WBC count < 4,000 indicates?

A

(leukopenia) occurs in many forms of bone marrow failure and may occur in sepsis in young children or in elderly.

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8
Q

Persistent increase in WBC indicates what?

A

worsening of an infectious process

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9
Q

A reduction in the WBC count to the normal range from previously elevated count indicates?

A

indicates resolution of an infection

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10
Q

A dramatic decrease in WBC count below normal range may indicate?

A

marrow failure

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11
Q

WBC interfering factors?

A 
Eating, physical activity, stress - increase
Pregnancy and labor - increase 
splenectomy - persistent mild increase
morning - low
evening - high
newborns infants - high  
Elderly - low
Drugs - increase or decrease .
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12
Q

What is a differential WBC and how are they measured?

A

Differential count measures the percentage of each type of leukocyte. An increase in the percentage of one type means a decrease in the percentage of another.
Identified by their morphology on a peripheral blood smear or by automated counters

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13
Q

List the five types of WBCS and their respective amounts in the body

A 
Neutrophils:       55-70%
Lymphocytes:    20-40%
Monocytes:         2-8%
Eosinophils:        1-4%
Basophils:         0.5-1.0%
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14
Q

General Neutrophil info and function

A

Most common granulocyte, produced in 7-14 days, exists in circulation only 6 hours.
Primary function is phagocytosis

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15
Q

How does a shift to the left affect neutorphils and what does it predict?

A

Acute bacterial infections and trauma stimulate production resulting in an increased WBC count. Sometimes early immature forms enter the circulation (bands or stab cells) which is referred to as a shift to the left, indicating an ongoing acute bacterial infection

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16
Q

Causes of neutrophil increase?

A 
strenuous exercise
menstruation
pregnancy.  
bacterial infection
some neoplastic disorders
ischemia
some autoimmune disorders
some meds such as steroids and epinephrine.
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17
Q

What do Eosinophils and Basophils do?

A

Both, especially eosinophils, are involved in allergic reactions and can perform phagocytosis of antigen-antibody complexes. As the allergic response decreases, the counts decrease

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18
Q

Do basophils respond to bacterial and viral infections?

A

No

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19
Q

What agents do basophils release and how do they affect the allergic reaction?

A

Basophils contain heparin, histamine, and serotonin in the cytoplasm. They infiltrate tissue involved in the allergic reaction and further the inflammatory reaction. Parasites may stimulate their production.

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20
Q

What causes eosinophil increases?

A

allergies
asthma
eczema

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21
Q

Does the differential count separate T and B cells?

A

No

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22
Q

What causes an increase in lymphocytes?

A

tuberculosis
acute bowel infections
infectious mononucleosis

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23
Q

Role of lymphocytes?

A

Function to fight chronic bacterial infection and acute viral infections

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24
Q

What are monocytes and what do they produce?

A

these are phagocytic cells that fight bacteria similarly to neutrophils. They remove necrotic debris and microorganisms by phagocytosis
Produce interferon, the body’s endogenous immunostimulant
Can be produced more rapidly and can spend longer time in circulation than neutrophils

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25
Q

What causes an increase in monocytes?

A

May increase in tuberculosis, rheumatoid arthritis, and systemic lupus erythematosus

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26
Q

What is the formula for the absolute count?

A

Multiply the differential count percentage by the total WBC count

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27
Q

What is the formula for the absolute neutrophil count (ANC) and what does it indicate?

A

multiply the WBC count by the percent neutrophils plus the percent bands
helpful in determining the patient’s risk for infection.

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28
Q

What may the patient need if ANC < 1000?

A

the patient may need isolation as they could be immunocompromised

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29
Q

Causes of leukocytosis? (8) DONT LIST (acronym)

A

DEHYDRATION – causes increase in WBC count by itself but also causes hemoconcentration to increase the WBC count
OTHER malignancy – advanced non-marrow cancers (lung) may cause leukocytosis
Infection
NECROSIS and inflammation – WBC response initiated by recognition of necrotic tissue as foreign
TRAUMA, stress, or hemorrhage – hormonal influence (epinephrine) probably causes leukocytosis

LEUKEMIC neoplasia or other myeloproliferative disorders – neoplastic cells are produced by the marrow and released into the bloodstream – leukemias, lymphomas
INFECTION
STEROID use – glucocorticosteroids stimulate WBC production
THYROID storm – WBC count influenced by thyroid hormones

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30
Q

Causes of Leukopenia (8) CHAD DOBB (acronym)

A

CONGENITAL marrow aplasia
HYPERSPLENISM – spleen more aggressively extracts WBCs from the bloodstream
AUTOIMMUNE disease – accelerated removal of WBCs
DRUG toxicity – cytotoxic chemotherapy as well as other drugs
DIETARY deficiency – Vitamin B12, iron, folate
OVERWHELMING infections
BONE marrow failure – aplastic anemia
BONE marrow infiltration (myelofibrosis) – WBC production reduced

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31
Q

Function of the RBC count? Normal values?

A

Represents different ways of evaluating the number of RBCs in the blood.Closely related to hemoglobin and hematocrit levels

Women lower values than men.
4.2-5.4 x 106/µL vs. 4.7-6.1 x 106/µL
counts tend to decrease with age

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32
Q

When is the RBC useful

A

It is repeated in patients with ongoing bleeding or as a routine part of the CBC and is a key part in evaluating anemic patients

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33
Q

What can shorten the lifespan of RBC’s?

A 
Abnormal RBCs get extracted earlier.
Intravascular trauma (artificial heart valves, atherosclerotic plaques) and an enlarged spleen (will destroy and remove normal RBCs) may shorten life span
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34
Q

What stimulates RBC production and how long do RBCs typically survive

A

Erythropoietin stimulates RBC production

RBCs normally survive about 120 days

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35
Q

Interfering factors of RBC count

A

Pregnancy causes a decrease in RBCs due to dilution from increases in normal body fluid
High altitudes cause an increase in RBCs –respond to decreased oxygen available
dehydration factitiously increases count, overhydration decreases the RBC count
Drugs – may increase or decrease the RBC count

36
Q

What increases the RBC (5) CHPSS

A

CONGENITAL heart disease – may cause chronically low oxygen levels to cause RBCs to increase
HEMOGLOBINOPATHIES, thalassemia trait –decreased oxygen carrying capacity of abnormal hemoglobin leads to increased production of RBCs
POLYCYTHEMIA vera – bone marrow inappropriately produces RBCs in great numbers
SEVERE COPD – chronic hypoxia causes RBC production as a physiologic response
SEVERE dehydration (severe diarrhea or burns) – total blood volume decreases but number of RBCs stays the same

37
Q

What decreases the RBC?

A

Anemia – decreased RBC counts
Hemoglobinopathy - may cause decreased RBC counts and survival
Cirrhosis – chronic fluid overload leads to diluted RBCs
Hemolytic anemia – RBC survival decreased
Hemorrhage – RBCs decrease with active bleeding but it takes several hours for the count to fall. If blood volume is replenished with fluid then the RBC count will fall
Dietary deficiency – iron, folate, B12 deficiencies may cause decreased number or size
Bone marrow failure – decreased production
Prosthetic valves – mechanical trauma causing shorter survival time
Renal disease – erythropoietin made in kidneys and stimulates RBC production. Reduced erythropoietin decreases RBC production
Normal pregnancy – increased blood volume leading to overhydration as well as a relative “malnourished” state
Rheumatoid/collagen vascular diseases
Lymphoma
Multiple myeloma
Leukemia
Hodgkin Disease

38
Q

What measurements make up the red blood cell indices?

A

Mean Corpuscular Volume (MCV)
Mean Corpuscular Hemoglobin (MCH)
Mean Corpuscular Hemoglobin Concentration (MCHC)
Red Blood Cell Distribution Width (RDW

39
Q

What information do the red blood cell indices provide and what do they help classify?

A

Provide information about the size, weight, and hemoglobin concentration of the RBCs and helps classify anemias

40
Q

What values are used to calculate the red blood cell indices?

A

The results of the RBC count, hematocrit, and hemoglobin are used to calculate the RBC indices

41
Q

What does the Mean Corpuscular Volume measure, what is the normal range, what is the formula?

A 
Measures the average volume, or size of a single RBC
Normal = 80-95 fL
Used to classify anemias
MCV = hematocrit/RBC count
Normal values vary by age and gender
42
Q

What does an increase or decrease in MCV mean?

A

When MCV is increased, the RBC is large, or macrocytic
When MCV is decreased, the RBC is small, or microcytic
When MCV is normal, the RBC is normal size, or normocytic

43
Q

What can cause increased MCV?

A

Pernicious anemia (vitamin B12 deficiency) and folic acid deficiency
Antimetabolite therapy – chemotherapy that acts as vitamin B12 and folate inhibitors
Alcoholism – due to malnutrition
Chronic liver disease – due to malnutrition, chronic illness, altered erythropoietin

44
Q

What causes decreased MCV?

A

Iron deficiency anemia
Thalassemia
Anemia of chronic illness

45
Q

What does the Mean Corpuscular Hemoglobin Concentration (MCHC) measure, what is the normal range, what is the formula?

A

Measures the average concentration or percentage of hemoglobin within a single RBC.
Normal = 32-36 g/dL (or 32-36%)
MCHC is calculated by the hemoglobin divided by the hematocrit

46
Q

What does an increase or decrease in MCHC mean?

A

When the MCHC is normal, it is normochromic. When the MCHC is decreased, the cell is deficient of hemoglobin and is hypochromic. RBCs cannot be hyperchromic as only so much hemoglobin can fit into the RBC.

47
Q

What causes an increased MCHC?

A

Spherocytosis – automated cell counter’s false perception of an elevation caused by variation in the shape of the RBC
Intravascular hemolysis – caused by free hemoglobin in the blood that gets counted by the automated counter
Cold agglutinins – causes misperception of increased MCV and decreased hematocrit leading to a calculated falsely high MCHC

48
Q

What causes a decreased MCHC?

A

Iron deficiency anemia

Thalassemia

49
Q

What does the Mean Corpuscular Hemoglobin measure, what is the normal range, what is the formula?

A

Measures the average amount (weight) of hemoglobin within a RBC
Normal = 27-31 pg
MCH is calculated by the hemoglobin divided by the RBC count

50
Q

What is the Red blood cell distribution width (RDW) and what are the normal values?

A

Indicates the variation in RBC size and is calculated by a machine using the MCV and RBC values
RDW is an indicator of the degree of anisocytosis, a blood condition with RBCs of variable and abnormal size
Normal = 11-14.5%

51
Q

What causes Increased RDW?

A

Increased RDW
Iron deficiency anemia, B12 or folate deficiency anemia – RBC fragmentation alters RBC size and shape. New RBCs produced when the deficiency was the greatest will be different in size and shape than the older RBCs produced before the deficiencies were as severe
Hemoglobinopathies (Sickle cell disease) – fragmentation increases RDW variation
Increased RDW
Hemolytic anemias – fragmentation increases RDW variation
Posthemorrhagic anemias – marrow responds to bleeding by releasing premature RBCs which are larger and cause RDW variability

52
Q

RBC indices interfering factors (6) CALMED

A

COLD agglutinins falsely elevates MCHC, MCH, and MCV
ABNORMAL size may affect the MCH and MCHC
LARGE RBC precursors (reticulocytes) cause automated counters to indicate high hemoglobin levels so the MCV, MCHC, and MCH are calculated falsely high
MARKED elevations in lipid levels cause automated counters to indicate high hemoglobin levels so the MCV, MCHC, and MCH are calculated falsely high
EXTREMELY elevated WBC counts may increase MCV and MCH with automatic counters
DRUGS may increase the MCV

53
Q

Name the four types of anemias

A

Normocytic Normochromic Anemia
Microcytic Hypochromic Anemia
Microcytic Normochromic Anemia
Macrocytic Normochromic Anemia

54
Q

Causes of Normocytic Normochromic Anemia

A 
Iron deficiency (detected early)
Chronic illness (sepsis, tumor)
Acute blood loss
Aplastic anemia
Acquired hemolytic anemias
55
Q

Causes of Microcytic Hypochromic Anemia

A

Iron deficiency (detected late)
Thalassemia
Lead poisoning

56
Q

Causes of Microcytic Normochromic Anemia

A

Renal disease due to loss of erythropoietin

57
Q

Causes of Macrocytic Normochromic Anemia

A 
Vitamin B12 or folic acid deficiency
Chemotherapy
Some myelodysplastic syndromes
Myeloid leukemia
Ethanol toxicity
Thyroid dysfunction
58
Q

What does Hematorcrit (Hct) measure and what are the normal values?

A

Measures the percentage of total blood volume made up by RBCs

Normal values vary by gender and age. Women tend to have lower values than men (37-47% vs. 42-52%).

59
Q

What does Hct closely reflect

A

Hct closely reflects the hemoglobin and RBC values
Hct is usually about 3 times the hemoglobin concentration when RBCs are of normal size and contain normal amounts of hemoglobin

60
Q

What do increased level of Hct indicate?

A

erythrocytosis

61
Q

What do decreased levels of Hct indicate?

A

anemia

62
Q

What are the interfering factors of Hematocrit?

HIP HEAD

A

HIGH altitudes cause increased Hct values as a physiologic response
IMMEDITATELY after hemorrhage, values may not be reliable as the percentage of total blood volume taken up by RBCs has not changed
PREGNANCY can cause a slight decrease because of chronic hemodilution
HEMODILUTION and dehydration
EXTREMELY elevated WBC counts decrease Hct, falsely indicating anemia
ABNORMALITIES in RBC size may alter Hct values – larger RBCs are associated with higher Hct because the larger RBCs take up a greater percentage of the total blood volume
DRUGS may decrease Hct

63
Q

What does hemoglobin (Hgb) measure and what are its normal values?

A

Measures the total amount of Hgb in the peripheral blood.
Hgb determines the oxygen carrying capacity of the blood and also acts as an acid base buffer system

Normal values vary by gender and age. Women tend to have lower values than men (12-16 g/dL vs. 14-18 g/dL).

64
Q

What are the risks in a critically low Hgb level?

A

an increased risk for angina, heart attack, congestive heart failure, and stroke.

65
Q

What are the risks for a critically high Hgb level

A

sludging occurs, leading to stroke and organ infarction

66
Q

What can the Hgb and Hct in combo be used for?

A

used to determine need for transfusion

67
Q

When should a transfusion be considered for a healthy person? younger patient? older patient?

A

healthy person: transfusion should be considered when Hgb < 8 or Hct < 24.
younger patients, a Hgb of 6 may be acceptable
older patients who are already compromised with multiple comorbidities, transfusion may be recommended when Hgb < 10

68
Q

Hgb interfering factors

A 
Pregnancy: slight decrease in Hgb
Slight diurnal variation in Hgb levels – highest around 8 AM and lowest around 8 PM with as much as a 1 g/dL variation
Heavy smokers have higher Hgb levels
High altitudes cause an increased Hgb
Drugs may increase or decrease Hgb
69
Q

What is the platelet count used for and when is it used?

A

An actual count of the number of platelets (thrombocytes) per cubic milliliter of blood.
Test is performed as part of a routine CBC and in patients with:
petechiae
spontaneous bleeding
increased heavy menses
thrombocytopenia
Test is used to monitor the course of the disease or therapy for thrombocytopenia or bone marrow failure.

70
Q

What is the normal count for platelets?

A

Normal counts are 150,000 – 400,000/mm3

71
Q

What does a platelet count < 1000 indicate?

A

thrombocytopenia

72
Q

Platelet counts greater than 400,000 indicate?

A

thrombocytosis

73
Q

Platelet ounts greater than 1 million indicate?

A

thrombocythemia. This can cause vascular thrombosis with tissue or organ infarction. A bleeding tendency could occur even with thrombocytosis as platelet function (aggregation) may be abnormal

74
Q

Causes of Thrombocytopenia

A

Reduced production of platelets – due to bone marrow failure or infiltration of fibrosis or tumor
Accelerated destruction of platelets – due to antibodies, infections, drugs, prosthetic heart valves
Dilution with large volumes of blood transfusions containing few if any platelets
Hypersplenism – enlarged spleen extracts more platelets, both aging and new
Hemorrhage – platelets are lost in the bleeding process. Replenishing blood volume and RBC count dilutes the remaining platelets
Immune thrombocytopenia (idiopathic thrombocytopenia, posttransfusion, drug induced) – antibodies against antigens on the platelet cell membrane destroy the platelets
Leukemia and other myelofibrosis disorders – marrow replaced by neoplastic or fibrotic tissue, leading to decreased number and function of megakaryocytes so platelets are not produced
Thrombotic thrombocytopenia
Graves disease
Inherited disorders
DIC – ongoing thrombosis consumes platelets
Systemic lupus erythematosus
Pernicious anemia – vitamin B12 is necessary for platelet production
Hemolytic anemia
Cancer chemotherapy – affects the bone marrow
Infection – especially when patient is immunocompromised

75
Q

Causes of thrombocytosis

A

Malignant disorders – leukemia, lymphoma, solid tumors
Polycythemia vera – hyperplasia of all marrow cell lines
Postsplenectomy syndrome – extracting aging platelets is not done very effectively by other organs
Rheumatoid arthritis
Iron deficiency anemia or following hemorrhagic anemia – anemia causes stimulation of cellular production by the marrow

76
Q

Platelet count interfering factors

A

High altitudes may increase platelet levels
Platelets can clump together, so automated counting may have a 10-15% error
Strenuous exercise may increase levels
Decreased levels before menstruation
Drugs may increase or decrease levels

77
Q

What does the Mean Platelet Volume (MPV) measure? what is the normal range?

A

Measures the volume of a large number of platelets.
Varies with total platelet production.

The MPV ( normal range 7.4-10.4 fL) is useful in the differential diagnosis of thrombocytopenia

78
Q

What causes an increase in the MPV

A

In thrombocytopenia, immature platelets larger than normal platelets are released, so the MPV increases.

79
Q

What causes a decrease in the MPV

A

When bone marrow production is inadequate, the platelets are small with a low MPV.

80
Q

What does a peripheral blood smear look for?

A 
A smear of peripheral blood can be examined for normal quantity of RBCs, WBCs, and platelets, as well as normal size, shape, and color of RBCs, as well as normal WBC differential count
RBC Size Abnormalities
RBC Shape Abnormalities
RBC Color Abnormalities
RBC Intracellular Structure
81
Q

Name the RBC size abnormalities and what causes them?

A

Microcytes (small RBCs) – iron deficiency, thalassemia, hemoglobinopathies
Macrocytes (larger size) – vitamin B12 or folic acid deficiency, reticulocytosis due to increased RBC production, liver disorder

82
Q

Name the RBC shape abnormalities?

A

Sickle cells – bipolar speculated RBCs pointed at both ends
Schistocytes – mechanical destruction of RBCs in circulation causing helmet-like or fragmented distorted RBCs
Spherocytes – small and round

83
Q

Name the RBC color abnormalities?

A

Hypochromic – pale cells caused by iron deficiency, thalassemia
Hyperchromasia – cells are more colored caused by concentrated Hgb due to dehydration

84
Q

What are howell-jolly bodies?

A

small round remnants of nuclear material remaining in RBC. Present after a surgical splenectomy, hemolytic anemia, megaloblastic anemia, functional asplenia (after splenic infarction)

85
Q

What is basophilic stippling?

A

(bodies enclosed or included in cytoplasm of RBCs) – lead poisoning, reticulocytosis

86
Q

What are normoblasts?

A

immature RBCs that have a nucleus. . Can be caused by anemia, chronic hypoxemia, marrow occupying neoplasm or fibrotic tissue

Lab Medicine (17 decks)

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