Red Blood Cell Disorders Flashcards
(108 cards)
1
Q
Define anemia.
A
A reduction in red cell mass with consequent decrease in oxygen transport capacity of blood
2
Q
What are the three clinical parameters used in testing for anemia?
A
- Red cell count
- hemoglobin concentration
- hematocrit
*all reflect but do not directly measure red cell mass
3
Q
What is the result of impaired tissue oxygenation that is associated with anemia?
A
- shortness of breath
- weakness
- fatigue
- pallor
4
Q
What are the three common mechanisms for establishing anemia?
A
- RBC loss (hemorrhage, trauma, GI disease)
- Decreased survival of RBC (malaria, transfusions, etc)
- Decreased production of RBC (nutrition deficiency, aplastic anemia, myelophthistic processes)
5
Q
What is “aplastic anemia?”
A
a condition that occurs when the body stops producing enough new RBCs
6
Q
What is polycythemia?
A
an increase in red cell mass (opposite of anemia)
7
Q
What are the laboratory tests for anemia?
A
- Complete Blood Count (CBC)
- Blood smear review
- Reticulocyte Count (new/immature RBC)
- Iron Indices (transferrin, ferritin, B12, folate)
- Hemolysis Work-up (bilirubin, haptoglobin, LDH, Coomb’s test, Plasma hemoglobin, electrophoresis)
8
Q
What is the Coomb’s Test?
A
It detects antibodies against RBCs that are present unbound in the patient’s serum. In this case, serum is extracted from the blood sample taken from the patient.
(“Coomb” rhymes with “womb” = common in prenatal testing)
9
Q
Hemorrhage can be either _____ or ______.
A
acute
chronic
10
Q
How much blood loss can a young, healthy individual handle with few symptoms?
A
500-1000 mL
15-20% total blood volume
11
Q
Some healthy individuals could experience a ______ response (sweating, weakness, nausea, slowed HR, and hypotension) with a loss of 1000mL. What level of rapid blood loss will produce shock?
A
vasovagal
2000 mL
12
Q
With controlled blood loss, how long does it take for interstitial fluid to redistribute into the vascular space? Why does it do this?
A
24 hours
-its an attempt to re-expand the vascular volume
13
Q
RBC production is mediated by _______. RBC production will cause an increase in the ______ count in the peripheral blood.
A
erythropoietin
reticulocyte
14
Q
What is chronic hemorrhage?
A
the rate of RBC loss exceeds the capacity for RBC regeneration (could be due to decreased iron that is available)
15
Q
What are two common causes of iron deficiency?
A
- Chronic bleeding of GI tract due to ulcer or neoplasm
2. Menorrhagia (heavy menstrual bleeding)
16
Q
______ anemias are due to decreased red blood cell survival.
A
Hemolytic
17
Q
Hemolytic Anemia can be either _____ or ______.
A
intravascular extravascular (more common)
18
Q
What is the difference between intravascular and extravascular hemolytic anemia?
A
intravascular: destruction of red cells within the circulation
extravascular: destruction of red cells within the reticuloendothelial system (tissue macrophages of the spleen and liver)
19
Q
Intravascular hemolysis can be immune, such as in _________, or it can be non-immune, such as in _______.
A
Immune = transfusion reactions Non-immune = mechanical trauma such as shearing by defective heart valve
20
Q
What is the key feature of intravascular hemolysis?
A
decrease in serum haptoglobin
this causes a problem because hemoglobin»_space;haptoglobin….so now hemoglobin is excreted in the urine = hemoglobinuria
21
Q
True or False: Jaundice is associated with intravascular hemolysis.
A
True
hemoglobin»haptoglobin = hemoglobinuria
hemoglobin = toxic to kidney
iron accumulates in proximal tubules = hemosiderinuria
heme conversion to bilirubin = jaundice
degree of jaundice depends on fxnl capacity of the liver
22
Q
True or False: Both intra- and extra-vascular hemolysis have immune and non-immune causes.
A
True
23
Q
Immune-related extravascular hemolysis is caused by ____ defects.
A
extrinsic
24
Q
Non-immune related extravascular hemolysis is caused by _____ defects.
A
intrinsic
25
Give three examples of extrinsic (immune) defects.
1. autoimmune
2. erythroblastosis fetalis
3. transfusion reaction
26
Give three examples of intrinsic (non-immune) defects.
1. RBC membrane defects
2. hemoglobinopathies
3. metabolic defects
27
_______ is also associated with extravascular hemolysis (destruction in the spleen or liver) because free hemoglobin is not released directly into the blood/urine and breakdown products are therefore increased.
jaundice
28
True or False: Hepatosplenomegaly is associated with intravascular hemolysis.
false, EXTRAvascular...spleen and liver breakdown the RBC
29
With extravascular hemolysis, which defect type is inherited?
intrinsic are inherited (non-immune defects)
- hemoglobin abnormality
- membrane abnormality
- lack of globin chains
- metabolic defect
30
Classify "hereditary spherocytosis" based on type of hemolytic anemia and defect.
```
EXTRAvascular hemolysis (spleen or liver)
INTRINSIC defect
MEMBRANE defect
```
31
What is hereditary spherocytosis?
an inherited defect in the red cell membrane that results in less deformability of the cell = can't squeeze through splenic sinusoids = sequestered and destroyed
32
What do spherocytes look like?
Round balls, not biconcave disks
33
Hereditary spherocytosis is either a qualitative or quantitative deficiency of which structural protein of the cytoskeleton?
spectrin
| Spectrin + Spheres = MINE
M embrane defect
IN trinsic defect
E xtravascular hemolysis
34
How serious is Hereditary spherocytosis? Is it curable?
its an autosomal dominance inheritance pattern that manifests in adult life with VARIABLE severity
- removal of the spleen results in normal RBC survival but not normal red cell morphology
- following splenectomy, spherocytes ARE still produced but destruction of cells is decreased
35
Sickle Cell anemia is a type of ________ hemolysis associated with ________ defects of the _______.
extravascular
intrinsic
hemoglobin
36
Sickle cell anemia is autosomal _____ condition that causes a _______ substitution in DNA between valine and glutamic acid at position 6 in the beta chain.
codominant (occurs in homozygotes for HbS)
| single base pair
37
What happens to the hemoglobin in sickle cell anemia?
the globin chain is defective and causes the hemoglobin to gel upon deoxygenation and assume its sickle shape
38
Why are the sickled cells a problem?
- they are rigid and vulnerable to splenic sequestration
| - they can block the microcirculation causing ischemia and/or infarction
39
What are the two leading causes of ischemia-related death for patients affected by Sickle Cell Anemia?
1. Acute chest syndrome
| 2. Stroke
40
True or False: Heterozygotes of sickle cell are clinically asymptomatic because less than half of the hemoglobin is abnormal and HbS concentration is too low to cause sickle shaped cells.
True,
41
___% of blacks in the USA are heterozygous carriers of sickle cell trait.
8
42
True or False: Autosplenectomy is a complication of hereditary spherocytosis.
False, autosplenectomy = sickle cell anemia
43
What is Thalassemia?
INTRINSIC defect of EXTRAVASCULAR hemolysis
| -results in diminished or absent synthesis of either the alpha or beta globin chains of hemoglobin
44
The type of thalassemia is named for the ____.
globin chain that is produced in a reduced amount
45
What is the principal clinical manifestation of thalassemia?
anemia (due to decreased hemoglobin production)
thalassemia leads to anemia...thalassemia leads to anemia...thalassemia leads to anemia....thalassemia leads to anemia....thalas.....you get it
46
True or False: Thalassemia is common in persons of Mediterranean, African, and Southeast Asian descent.
True
47
True or False: Thalassemia reduces the impact of malaria.
True
(both sickle cell and thalassemia change the hemoglobin chains...and they both provide protection against malaria. coincidence?)
48
In almost all cases of Thalassemia there is a moderate to marked ________ with target cells and ________ of the RBCs on the blood smear.
```
microcytosis (low MCV= small cells)
basophilic stippling (small dots in the periphery from ribosomes)
```
49
What type of deficiency causes a metabolic defect (intrinsic) that results in extravascular hemolytic anemia?
Glucose-6 Phosphate Dehydrogenase (G6PD) deficiency
- sex linked defect (primarily black men)
- red cells are susceptible to oxidant injury usually precipitated by drugs/toxins or infections
- RBC membrane is less flexible and subjected to extravascular hemolysis in the spleen
50
What is the cytomorphologic hallmark of G6PD deficiency?
"bite" cells
| -not very flexible
51
True or False: In the absence of the oxidant trigger (antimalarials, sulfonamides, etc), G6PC deficiency is asymptomatic.
True
52
True or False: Bite Cells are more flexible than normal RBCs.
False
53
Extrinsic defects associated with extravascular hemolysis. include _______ disease of the newborn and _____ hemolysis.
hemolytic
| autoimmune
54
Hemolytic disease of the newborn occurs _______.
in utero
55
What is another name for hemolytic disease of the newborn (HDN)? What causes it?
erythroblastosis fetalis
- blood group incompatibility between mother and fetus
- fetal RBC expresses antigens inherited from the father that are not present in the mother
- during the third trimester or during delivery, the mother is exposed to the antigens = antibody response
- during future pregnancy, the mother's immune system makes antibodies that cross the placenta and attach to fetal RBC = extravascular hemolysis of RBC in new fetus (liver and spleen)
56
Which antigens are most important in the Hemolytic Disease of the Newborn?
ABO
| Rh (anti-D)
57
Rh-negative mothers are given _____ within 72 hours of delivery of an Rh-positive fetus. Why?
anti-D (Rhogam)
-anti-D binds to the Rh-positive fetal cells and removes them from maternal circulation before the mother can generate an antibody response and become sensitized
58
When does ABO hemolytic disease occur?
Group A or Group B infants born to group O mothers
-certain group O mothers produce IgG anti-A or anti-B in addition to the usually IgM antibodies (lysis of fetal RBC is minimal because fetal cells express A or B antigens weakly)
59
True or False: IgM does not cross the placenta.
True
60
True or False: IgG can cross the placenta.
True
```
IgM = M om only
IgG = G oes across
```
61
What is a hemolytic transfusion reaction?
a type of intravascular hemolysis
-transfusion of incompatible red cells into a sensitized patient results in binding of antibody (in patient) to antigen (transfused RBC) with activation of complement (lyses antibody-coated RBC) and immediate intravascular hemolysis
62
Which antigen type is most important in hemolytic transfusion reactions?
ABO
63
Hemolytic transfusion reactions will activate the coagulation cascade with bleeding, _____ failure, ______ and ______.
renal
shock
death
64
True or False: Hemolytic Transfusion Reactions are always intravascular.
False,
following transfusion = intravascular
delayed reaction = extravascular
65
What is autoimmune hemolysis?
- extravascular or intravascular hemolysis reaction
- patient makes antibodies to his/her own RBCs
- antibody coated cells can be removed by the reticuloendothelial system = extravascular
- antibody coated cells can be lysed via complement activation = intravascular
66
What is the hallmark of autoimmune hemolytic anemia?
spherocytes
67
What are spherocytes?
- -partial loss of red cell membrane (cytoskeleton) makes the RBC ball-like and less deformable
- they are sequestered by the spleen and therefore further enhance the anemia
68
What test is done to determine presence of autoimmune hemolytic anemia?
The Coomb's Test
| -agglutinaton test/RBC aggregation
69
Name two examples of extrinsic defects contributing to hemolytic anemia that are the result of mechanical trauma. Are these intra- or extra-vascular hemolysis?
1. Cardiac Valve Prosthesis
2. DIC
**INTRAVASCULAR** occuring within the circulation (not the reticuloendothelial/spleen/liver)
70
How do cardiac valve prostheses contribute to intravascular hemolytic anemia?
-RBCs are disrupted by physical trauma as they pass through areas of turbulence and abnormal pressure related to abnormal valve function
71
How does DIC contribute to intravascular hemolytic anemia?
-RBCs are lysed as they pass through fibrin clots/strands in the microcirculation
72
What is a good indication of hemolysis due to mechanical trauma?
Schistocytes
| -RBC fragments that lost a large portion of their membranes and look mishapen and squashed
73
True or False: Infections can cause intravascular hemolytic anemia.
True!
- parasites can infect RBCs and cause lysis of RBC during maturation (ex. Malaria)
- different degrees experienced by different patients
74
How do nutrition deficiencies lead to anemia?
deficiency of a substance needed for erythropoiesis will decrease the red cell PRODUCTION
75
What are the common nutrition deficiencies associated with anemia?
iron
folate
B12
76
_____ deficiency is the most common cause of anemia worldwide. It is needed for _______, _______, and a variety of enzymes.
Iron
hemoglobin
myoglobin
77
What are the common settings for iron deficiency anemia?
1. inadequate intake (infants, alcoholics, elderly)
2. increased demands (pregnancy, adolescents)
3. increased loss (bleeding, cancer)
78
What happens to red cells when there is inadequate iron intake?
they become smaller (MICROCYTIC) and contain less hemoglobin (HYPOCHROMIC) than usual
79
Anemia develops _____ and low levels of Hb can be tolerated with _____ symptoms.
insidiously (gradually)
| minimal
80
Describe the laboratory results used to study iron deficiency anemia.
- low serum iron
- low serum ferritin
- increased serum iron-binding capacity
- microcytic red cells
- hypochromic red cells
81
True or False: Iron deficiency anemia may be linked to a more serious condition.
True, chronic blood loss associated with cancer is a possibility
82
Both B12 and folate are involved (either directly or as cofactors) in the synthesis of _______, one of the _____ bases in DNA.
thymidine
| purine
83
________ anemia results from folate and B12 deficiency.
Megaloblastic
84
Why is it called "megaloblastic" anemia?
B12 + folate = thymidine = DNA base
- impaired DNA synthesis = delayed mitotic division
- nucleus does not mature appropriately but RNA synthesis and cytoplasmic maturation proceed normally
- results = abnormally large red cell precursors (megalobasts), decreased production of mature RBC, and abnormally large red cells (macrocytes)
85
What is the histological evidence of megaloblastic anemia?
- abnormally large red and white cell precursors
- increased MCV
- hypersegmented neutrophils (lobulated)
86
Megaloblasts accumulate in the _____ and release too few RBCs into the peripheral blood, causing anemia.
bone marrow
87
Megaloblasts may undergo ______ in the marrow or may be destroyed by ______ cells in the marrow.
autohemolysis
phagocytic
(ineffective erythropoiesis)
88
True or False: The impairment of DNA synthesis associated with megaloblastic anemia is systemic and affects other rapidly dividing cells in the body.
True.
89
In what food source is folate found? Is it stored in the body?
in fresh vegetables (absorbed through proximal small intestine)
*body stores are SMALL*
90
In what food source is B12 found? Is it stored in the body?
in animal foods (absorbed in distal ileum; IF-b12 complex attaches to epithelial cells)
*body stores are LARGE
91
Absorption of B12 requires _____, a protein produced by parietal cells of the gastric mucosa.
intrinsic factor
92
Patients with _____ anemia have autoantibodies directed at intrinsic factor.
pernicious
| B12 deficient and association with atrophic gastritis
93
Which transport protein is responsible for delivering the absorbed B12 to the liver and other cells?
transcobalamins
| --glycoprotein produced by the salivary glands, protects b12 from acid degradation--
94
True or False: Folate deficiency can be associated with neurologic symptoms.
False, B12 can!!
95
Name two examples of anemia associated with decreased red cell production.
1. aplastic anemia
| 2. myelophthisic anemia
96
What is aplastic anemia?
a stem cell abnormality results in marked diminution of hematopoiesis
-production of all cellular elements of the blood are decreased
97
True or False: Over half of the cases of aplastic anemia have no known predisposing cause.
True, but viruses, drugs, and toxins have been implicated
98
What type of treatment for aplastic anemia has been successful, especially in patients under 40 years old?
bone marrow transplantation
99
What is myelophthisic anemia?
decreased production of red cells due to replacement (by tumor or fibrosis) of marrow elements
100
What is often seen on a blood smear in a patient with myelophthistic anemia?
mishapen RBCs resembling teardrops
101
What type of cancer is usually involved with myelophthistic anemia?
multiple myeloma
| metastatic cancer
102
What is polycythemia?
an increase in red cell mass (opposite of anemia)
"polyCYthemia"..."CYke! its not anemia"
103
______ polycythemia occurs with hemoconcentration of red cells due to dehydration, vomiting, diarrhear, or excessive use of diuretics.
Relative
104
______ polycythemia can be a primary or secondary phenomenon.
Absolute
105
When does primary absolute polycythemia occur?
(polycythemia vera) non-regulated proliferation of red cells and myeloid cells
- this is a stem cell disorder and is associated with normal or low levels of EPO
- causes sludging of red cells in capillaries = neurologic and visual abnormalities
106
How doe you treat polycythemia vera?
removal of excess RBC by phlebotomy
107
How does secondary absolute polycythemia occur?
through stimuli that increase EPO
| ex.: cyanotic heart disease, pulmonary disease, high altitude living, abnormal Hb, tumor producing EPO
108
_______ levels are helpful in distinguishing primary from secondary absolute polycythemia.
erythropoietin
primary = normal or suppressed levels
secondary = increased levels
