CBC Flashcards
Components of CBC with Differential
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)
What does CBC stand for
Complete blood count
Indications for CBC
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
White Blood cell Count - normal values, useful for?
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
WBC > 10,000 indicates?
infection, inflammation, tissue necrosis, or leukemic neoplasm.
What is a leukemoid reaction?
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
WBC count < 4,000 indicates?
(leukopenia) occurs in many forms of bone marrow failure and may occur in sepsis in young children or in elderly.
Persistent increase in WBC indicates what?
worsening of an infectious process
A reduction in the WBC count to the normal range from previously elevated count indicates?
indicates resolution of an infection
A dramatic decrease in WBC count below normal range may indicate?
marrow failure
WBC interfering factors?
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 .
What is a differential WBC and how are they measured?
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
List the five types of WBCS and their respective amounts in the body
Neutrophils: 55-70% Lymphocytes: 20-40% Monocytes: 2-8% Eosinophils: 1-4% Basophils: 0.5-1.0%
General Neutrophil info and function
Most common granulocyte, produced in 7-14 days, exists in circulation only 6 hours.
Primary function is phagocytosis
How does a shift to the left affect neutorphils and what does it predict?
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
Causes of neutrophil increase?
strenuous exercise menstruation pregnancy. bacterial infection some neoplastic disorders ischemia some autoimmune disorders some meds such as steroids and epinephrine.
What do Eosinophils and Basophils do?
Both, especially eosinophils, are involved in allergic reactions and can perform phagocytosis of antigen-antibody complexes. As the allergic response decreases, the counts decrease
Do basophils respond to bacterial and viral infections?
No
What agents do basophils release and how do they affect the allergic reaction?
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.
What causes eosinophil increases?
allergies
asthma
eczema
Does the differential count separate T and B cells?
No
What causes an increase in lymphocytes?
tuberculosis
acute bowel infections
infectious mononucleosis
Role of lymphocytes?
Function to fight chronic bacterial infection and acute viral infections
What are monocytes and what do they produce?
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
What causes an increase in monocytes?
May increase in tuberculosis, rheumatoid arthritis, and systemic lupus erythematosus
What is the formula for the absolute count?
Multiply the differential count percentage by the total WBC count
What is the formula for the absolute neutrophil count (ANC) and what does it indicate?
multiply the WBC count by the percent neutrophils plus the percent bands
helpful in determining the patient’s risk for infection.
What may the patient need if ANC < 1000?
the patient may need isolation as they could be immunocompromised
Causes of leukocytosis? (8) DONT LIST (acronym)
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
Causes of Leukopenia (8) CHAD DOBB (acronym)
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
Function of the RBC count? Normal values?
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
When is the RBC useful
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
What can shorten the lifespan of RBC’s?
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
What stimulates RBC production and how long do RBCs typically survive
Erythropoietin stimulates RBC production
RBCs normally survive about 120 days
Interfering factors of RBC count
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
What increases the RBC (5) CHPSS
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
What decreases the RBC?
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
What measurements make up the red blood cell indices?
Mean Corpuscular Volume (MCV)
Mean Corpuscular Hemoglobin (MCH)
Mean Corpuscular Hemoglobin Concentration (MCHC)
Red Blood Cell Distribution Width (RDW
What information do the red blood cell indices provide and what do they help classify?
Provide information about the size, weight, and hemoglobin concentration of the RBCs and helps classify anemias
What values are used to calculate the red blood cell indices?
The results of the RBC count, hematocrit, and hemoglobin are used to calculate the RBC indices
What does the Mean Corpuscular Volume measure, what is the normal range, what is the formula?
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
What does an increase or decrease in MCV mean?
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
What can cause increased MCV?
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
What causes decreased MCV?
Iron deficiency anemia
Thalassemia
Anemia of chronic illness
What does the Mean Corpuscular Hemoglobin Concentration (MCHC) measure, what is the normal range, what is the formula?
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
What does an increase or decrease in MCHC mean?
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.
What causes an increased MCHC?
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
What causes a decreased MCHC?
Iron deficiency anemia
Thalassemia
What does the Mean Corpuscular Hemoglobin measure, what is the normal range, what is the formula?
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
What is the Red blood cell distribution width (RDW) and what are the normal values?
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%
What causes Increased RDW?
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
RBC indices interfering factors (6) CALMED
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
Name the four types of anemias
Normocytic Normochromic Anemia
Microcytic Hypochromic Anemia
Microcytic Normochromic Anemia
Macrocytic Normochromic Anemia
Causes of Normocytic Normochromic Anemia
Iron deficiency (detected early) Chronic illness (sepsis, tumor) Acute blood loss Aplastic anemia Acquired hemolytic anemias
Causes of Microcytic Hypochromic Anemia
Iron deficiency (detected late)
Thalassemia
Lead poisoning
Causes of Microcytic Normochromic Anemia
Renal disease due to loss of erythropoietin
Causes of Macrocytic Normochromic Anemia
Vitamin B12 or folic acid deficiency Chemotherapy Some myelodysplastic syndromes Myeloid leukemia Ethanol toxicity Thyroid dysfunction
What does Hematorcrit (Hct) measure and what are the normal values?
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%).
What does Hct closely reflect
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
What do increased level of Hct indicate?
erythrocytosis
What do decreased levels of Hct indicate?
anemia
What are the interfering factors of Hematocrit?
HIP HEAD
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
What does hemoglobin (Hgb) measure and what are its normal values?
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).
What are the risks in a critically low Hgb level?
an increased risk for angina, heart attack, congestive heart failure, and stroke.
What are the risks for a critically high Hgb level
sludging occurs, leading to stroke and organ infarction
What can the Hgb and Hct in combo be used for?
used to determine need for transfusion
When should a transfusion be considered for a healthy person? younger patient? older patient?
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
Hgb interfering factors
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
What is the platelet count used for and when is it used?
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.
What is the normal count for platelets?
Normal counts are 150,000 – 400,000/mm3
What does a platelet count < 1000 indicate?
thrombocytopenia
Platelet counts greater than 400,000 indicate?
thrombocytosis
Platelet ounts greater than 1 million indicate?
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
Causes of Thrombocytopenia
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
Causes of thrombocytosis
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
Platelet count interfering factors
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
What does the Mean Platelet Volume (MPV) measure? what is the normal range?
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
What causes an increase in the MPV
In thrombocytopenia, immature platelets larger than normal platelets are released, so the MPV increases.
What causes a decrease in the MPV
When bone marrow production is inadequate, the platelets are small with a low MPV.
What does a peripheral blood smear look for?
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
Name the RBC size abnormalities and what causes them?
Microcytes (small RBCs) – iron deficiency, thalassemia, hemoglobinopathies
Macrocytes (larger size) – vitamin B12 or folic acid deficiency, reticulocytosis due to increased RBC production, liver disorder
Name the RBC shape abnormalities?
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
Name the RBC color abnormalities?
Hypochromic – pale cells caused by iron deficiency, thalassemia
Hyperchromasia – cells are more colored caused by concentrated Hgb due to dehydration
What are howell-jolly bodies?
small round remnants of nuclear material remaining in RBC. Present after a surgical splenectomy, hemolytic anemia, megaloblastic anemia, functional asplenia (after splenic infarction)
What is basophilic stippling?
(bodies enclosed or included in cytoplasm of RBCs) – lead poisoning, reticulocytosis
What are normoblasts?
immature RBCs that have a nucleus. . Can be caused by anemia, chronic hypoxemia, marrow occupying neoplasm or fibrotic tissue
