Chapter 14 – Red Blood Cell and Bleeding Disorders Flashcards
What is ANEMIA?
Anemia is defined as a reduction of the total circulating red cell mass below normal limits .
Anemia reduces the oxygen-carrying capacity of the blood, leading to tissue hypoxia.
How is anemia diagnosed?
In
practice, the measurement of red cell mass is not easy, and anemia is usually diagnosed based
on a reduction in the hematocrit (the ratio of packed red cells to total blood volume) and the
hemoglobin concentration of the blood to levels that are below the normal range.
These values
correlate with the red cell mass except when there are changes in plasma volume caused by
fluid retention or dehydration
What is hematocrit?
hematocrit is the ratio of packed red cells to total blood volume
What is hemoglobin?
hemoglobin concentration of the blood to levels that are below the normal range.
These values
correlate with the red cell mass except when there are changes in plasma volume caused by
fluid retention or dehydration
What is the second clinical useful approach classifies anemia?
A second clinically useful approach classifies anemia according to alterations in red cell morphology, which often point to particular causes.
Morphologic
characteristics providing etiologic clues include what?
Morphologic
characteristics providing etiologic clues include red cell:
- size (normocytic, microcytic, or macrocytic);
- degree of hemoglobinization, reflected in the color of red cells (normochromic or hypochromic); and
- shape.
Red cell size is classified as what?
- normocytic,
- microcytic, or
- macrocytic
degree of hemoglobinization
reflected in the color of red cells (normochromic or
hypochromic)
In general, microcytic hypochromic anemias are caused by what?
disorders of hemoglobin synthesis (most often iron deficiency)
macrocytic anemias often stem from
abnormalities that______________
impair the maturation of erythroid precursors in the bone marrow.
Normochromic, normocytic anemias have diverse etiologies; in some of these anemias, specific
abnormalities of red cell shape (best appreciated through visual inspection of peripheral
smears) provide an important clue as to the cause.
The other indices can also be assessed
qualitatively in smears, but precise measurement is carried out in clinical laboratories with
special instrumentation.
The most useful red cell indices are as follows:
- Mean cell volume
- Mean cell hemoglobin
- Mean cell hemoglobin concentration
- Red cell distribution width
Mean cell volume
Mean cell volume: the average volume of a red cell expressed in femtoliters (fL)
Mean cell hemoglobin
the average content (mass) of hemoglobin per red cell,
expressed in picograms
Mean cell hemoglobin concentration
the average concentration of hemoglobin in a given volume of packed red cells, expressed in grams per deciliter
Red cell distribution width
: the coefficient of variation of red cell volume
TABLE 14-1 – Classification of Anemia According to Underlying Mechanism
Mechanism
- BLOOD LOSS
- INCREASED RED CELL DESTRUCTION (HEMOLYSIS)
- DECREASED RED CELL PRODUCTION
TABLE 14-1 – Classification of Anemia According to Underlying Mechanism
BLOOD LOSS
Acute blood loss
Specific Examples
Trauma
TABLE 14-1 – Classification of Anemia According to Underlying Mechanism
BLOOD LOSS
Chronic blood loss
Specific Examples
- Gastrointestinal tract lesions,
- gynecologic disturbances
TABLE 14-1 – Classification of Anemia According to Underlying Mechanism
INCREASED RED CELL DESTRUCTION (HEMOLYSIS)
- Inherited genetic defects
- Red cell membrane disorders
- Enzyme deficiencies
- Hemoglobin abnormalities
- Acquired genetic defects
- Deficiency of
phosphatidylinositol-linked
glycoproteins - Antibody-mediated destruction
- Mechanical trauma
- Microangiopathic hemolytic
anemias - Cardiac traumatic hemolysis
- Repetitive physical trauma
- Infections of red cells
- Toxic or chemical injury
- Membrane lipid abnormalities
- Sequestration
- Deficiency of
TABLE 14-1 – Classification of Anemia According to Underlying Mechanism
INCREASED RED CELL DESTRUCTION (HEMOLYSIS)
Acquired genetic defects
- Deficiency of phosphatidylinositol-linked glycoproteins
- Antibody-mediated destruction
- Mechanical trauma
- Microangiopathic hemolytic anemias
- Cardiac traumatic hemolysis
- Repetitive physical trauma
- Infections of red cells
- Toxic or chemical injury
- Membrane lipid abnormalities
- Sequestration
TABLE 14-1 – Classification of Anemia According to Underlying Mechanism
INCREASED RED CELL DESTRUCTION (HEMOLYSIS)
Enzyme deficiencies
- Hexose monophosphate shunt enzyme deficiencies
- Glycolytic enzyme deficiencies
TABLE 14-1 – Classification of Anemia According to Underlying Mechanism
DECREASED RED CELL PRODUCTION
Nutritional deficiencies
- Deficiencies affecting DNA synthesis
- Deficiencies affecting hemoglobin synthesis
- Erythropoietin deficiency
- Immune-mediated injury of progenitors
- Inflammation-mediated iron sequestration
- Primary hematopoietic neoplasms
- Space-occupying marrow lesions
- Infections of red cell progenitors
- Unknown mechanisms
TABLE 14-1 – Classification of Anemia According to Underlying Mechanism
DECREASED RED CELL PRODUCTION
Inherited genetic defects
- Defects leading to stem cell depletion
- Defects affecting erythroblast maturation
INCREASED RED CELL DESTRUCTION (HEMOLYSIS)
Inherited genetic defects
Red cell membrane disorders
- Hereditary spherocytosis,
- hereditary elliptocytosis
INCREASED RED CELL DESTRUCTION (HEMOLYSIS)
Inherited genetic defects
Enzyme deficiencies
Hexose monophosphate shunt
enzyme deficiencies
- G6PD deficiency,
- glutathione synthetase deficiency
INCREASED RED CELL DESTRUCTION (HEMOLYSIS)
Inherited genetic defects
Enzyme deficiencies
Glycolytic enzyme deficiencies
- Pyruvate kinase deficiency,
- hexokinase deficiency
INCREASED RED CELL DESTRUCTION (HEMOLYSIS)
- Inherited genetic defects
- Enzyme deficiencies
- Glycolytic enzyme deficiencies
- Enzyme deficiencies
- Pyruvate kinase deficiency,
- hexokinase deficiency
INCREASED RED CELL DESTRUCTION (HEMOLYSIS)
- Inherited genetic defects
-
Hemoglobin abnormalities
- Deficient globin synthesis
-
Hemoglobin abnormalities
Thalassemia syndromes
INCREASED RED CELL DESTRUCTION (HEMOLYSIS)
- Inherited genetic defects
- Hemoglobin abnormalities
- Structurally abnormal globins (hemoglobinopathies)
- Hemoglobin abnormalities
- Sickle cell disease,
- unstable hemoglobins
INCREASED RED CELL DESTRUCTION (HEMOLYSIS)
- Acquired genetic defects
- Deficiency of phosphatidylinositol-linked glycoproteins
Paroxysmal nocturnal hemoglobinuria
INCREASED RED CELL DESTRUCTION (HEMOLYSIS)
- Acquired genetic defects
- Antibody-mediated destruction
- Hemolytic disease of the newborn (Rh disease),
- transfusion reactions,
- drug-induced,
- autoimmune disorders
INCREASED RED CELL DESTRUCTION (HEMOLYSIS)
- Acquired genetic defects
- Mechanical trauma
Hemolytic disease of the newborn (Rh disease), transfusion reactions, drug-induced, autoimmune disorders
INCREASED RED CELL DESTRUCTION (HEMOLYSIS)
- Acquired genetic defects
- Microangiopathic hemolytic anemias
- Hemolytic uremic syndrome,
- disseminated intravascular coagulation,
- thrombotic thrombocytopenia purpura
INCREASED RED CELL DESTRUCTION (HEMOLYSIS)
- Acquired genetic defects
- Cardiac traumatic hemolysis
Defective cardiac valves
INCREASED RED CELL DESTRUCTION (HEMOLYSIS)
- Acquired genetic defects
- Repetitive physical trauma
- Bongo drumming,
- marathon running,
- karate chopping
INCREASED RED CELL DESTRUCTION (HEMOLYSIS)
- Acquired genetic defects
- Infections of red cells
Malaria, babesiosis
INCREASED RED CELL DESTRUCTION (HEMOLYSIS)
- Acquired genetic defects
- Toxic or chemical injury
- Clostridial sepsis,
- snake venom,
- lead poisoning
INCREASED RED CELL DESTRUCTION (HEMOLYSIS)
- Acquired genetic defects
- Membrane lipid abnormalities
- Abetalipoproteinemia,
- severe hepatocellular liver disease
INCREASED RED CELL DESTRUCTION (HEMOLYSIS)
- Acquired genetic defects
- Sequestration
Hypersplenism
DECREASED RED CELL PRODUCTION
- Inherited genetic defects
- Defects leading to stem cell depletion
- Fanconi anemia,
- telomerase defects
DECREASED RED CELL PRODUCTION
- Inherited genetic defects
- Defects affecting erythroblast maturation
Thalassemia syndromes
DECREASED RED CELL PRODUCTION
- Nutritional deficiencies
- Deficiencies affecting DNA synthesis
B12 and folate deficiencies
DECREASED RED CELL PRODUCTION
- Nutritional deficiencies
- Deficiencies affecting hemoglobin synthesis
Iron deficiency anemia
DECREASED RED CELL PRODUCTION
- Nutritional deficiencies
- Erythropoietin deficiency
Renal failure, anemia of chronic disease
DECREASED RED CELL PRODUCTION
- Nutritional deficiencies
- Immune-mediated injury of
progenitors
- Immune-mediated injury of
Aplastic anemia, pure red cell aplasia
DECREASED RED CELL PRODUCTION
- Nutritional deficiencies
- Inflammation-mediated iron
sequestration
- Inflammation-mediated iron
Anemia of chronic disease
DECREASED RED CELL PRODUCTION
- Nutritional deficiencies
- Primary hematopoietic neoplasms
Acute leukemia, myelodysplasia, myeloproliferative disorders (
Chapter 13 )
DECREASED RED CELL PRODUCTION
- Nutritional deficiencies
- Space-occupying marrow lesions
- Metastatic neoplasms,
- granulomatous disease
DECREASED RED CELL PRODUCTION
- Nutritional deficiencies
- Infections of red cell progenitors
Parvovirus B19 infection
DECREASED RED CELL PRODUCTION
- Nutritional deficiencies
- Unknown mechanisms
Endocrine disorders, hepatocellular liver disase
Most often cause anemia due to iron deficiency, not bleeding per se.
gynecologic disturbances
Whatever its cause, when sufficiently severe anemia leads to certain clinical features.
- Patients appear pale.
- Weakness,
- malaise,
- and easy fatigability are common complaints.
- The lowered oxygen content of the circulating blood leads to dyspnea on mild exertion
- . Hypoxia can cause fatty change in the liver, myocardium, and kidney.
- If fatty changes in the myocardium are sufficiently severe, cardiac failure can develop and compound the tissue hypoxia caused by the deficiency of O2 in the blood.
- On occasion, the myocardial hypoxia manifests as angina pectoris, particularly when complicated by pre-existing coronary artery disease.
- With acute blood loss and shock, oliguria and anuria can develop as a result of renal hypoperfusion.
- Central nervous system hypoxia can cause headache, dimness of vision, and faintness.
The effects of acute blood loss are mainly due to what?
the loss of intravascular volume, which if
massive can lead to cardiovascular collapse, shock, and death.
In acute blood loss, how is it restored?
If the patient
survives, the blood volume is rapidly restored by the intravascular shift of water from the
interstitial fluid compartment.
This fluid shift results in hemodilution and a lowering of the hematocrit.
The reduction in oxygenation triggers increased secretion of erythropoietin from the
kidney, which stimulates the proliferation of committed erythroid progenitors (CFU-E) in the
marrow (see Fig. 13-1 ).
How long does it takes for the progeny of these CFU-Es to mature and
appear as newly released red cells (reticulocytes) in the peripheral blood.
about 5 days
How is the iron in the hemoglobin recaptured?
The iron in
hemoglobin is recaptured if red cells extravasate into tissues, whereas bleeding into the gut or
out of the body leads to iron loss and possible iron deficiency, which can hamper the restoration
of normal red cell coun
Significant bleeding results in predictable changes in the blood involving not only red cells, but
also white cells and platelets
T or F
True
What is the reason for leukocytosis when there is a mssive bleeding?
If the bleeding is sufficiently massive to cause a decrease in blood pressure, the compensatory release of adrenergic hormones mobilizes granulocytes from
the intravascular marginal pool and results in leukocytosis
What is the appearance of RBC initially in acute blood loss?
Initially, red cells
appear normal in size and color (normocytic, normochromic).
However, as marrow production
increases there is a striking increase in the reticulocyte count (reticulocytosis), which reaches
10% to 15% after 7 days
What is the appearance of reticulocytes?
Reticulocytes are larger in size than normal red cells (macrocytes) and have a blue-red polychromatophilic cytoplasm
.Early recovery from blood loss is also often
accompanied by thrombocytosis, which results from an increase in platelet production.
T or F
True
When does chronic blood loss induces anemia?
Chronic blood loss induces anemia only when the rate of loss exceeds the regenerative
capacity of the marroworwhen iron reserves are depleted and iron deficiency anemia appears;
this will be discussed later