RBC Flashcards
(126 cards)
1
Q
What is the term for excess of red blood cells?
A
Erythrocytosis
2
Q
What are reticulocytes?
A
Immature red blood cells (same things as polychromatophils but this is just what you call them in a NMB stain)
3
Q
What are polychromatophils?
A
Immature red blood cells (same things as reticulocytes but this is just what you call them with a Wright stain - pink)
4
Q
What hormone is responsible for RBC production?
A
Erythropoietin
5
Q
Which organ secretes erythropoietin?
A
Kidney
6
Q
What are the three major ‘pools’ for RBCs in the body?
A
- Precursor cells in bone marrow
- Blood
- Spleen
7
Q
What is the general cause of a primary erythrocytosis?
A
The bone marrow itself. The word ‘primary’ means that the cause is related to overproduction of RBCs themselves
8
Q
What is hemoconcentration?
A
The increased concentration of blood components (including RBCs) due to a decrease in plasma volume (the liquid component of blood) relative to the cellular elements.
9
Q
What is the most likely clinical cause of hemoconcentration?
A
When an animal or sample is dehydrated (when the body loses fluid, the volume of plasma decreases, leading to a relative increase in the concentration of blood cells and proteins)
10
Q
Why can erythrocytosis cause poor oxygenation?
A
Although there are extra red blood cells, too many can cause ‘sludging’, leading to impaired blood flow and poor oxygenation
11
Q
What are two main causes of relative erythrocytosis?
A
- Dehydration
- Splenic contraction
Relative means the actual number of RBCs in the body isn’t changing
12
Q
Why can splenic contraction temporarily cause hemoconcentration?
A
During times of increased demand for oxygen (ex. physical activity) the spleen contracts to release stored RBCs into circulation. This sudden release can increase the concentration of RBCs in the bloodstream, leading to hemoconcentration (normal, physiological process)
13
Q
What are the two types of absolute erythrocytosis?
A
- Primary (polycythemia)
- Secondary (appropriate vs. non-appropriate)
Absolute means the actual number of RBCs in the body is changing
14
Q
What changes in total protein will you see with hemoconcentration due to dehydration?
A
Increased total protein
When the volume of plasma decreases due to hemoconcentration, the concentration of proteins in the plasma increases (proteins make up a significant portion of the plasma)
15
Q
What changes in total protein will you see with hemoconcentration due to splenic contraction?
A
Normal total protein (since there is no evidence of dehydration, the plasma levels do not decrease, so total protein is not affected)
16
Q
What are the two categories of secondary erythrocytosis?
A
- Appropriate
- Inappropriate
17
Q
What is appropriate secondary erythrocytosis?
A
When erythrocytosis and erythropoietin production is the body’s appropriate response to hypoxia due to a disease unrelated to the bone marrow
18
Q
What three conditions can cause appropriate secondary erythrocytosis?
A
Heart failure, respiratory disease, and hyperthyroidism
19
Q
What is inappropriate secondary erythrocytosis?
A
When the kidney initiates erythrocytosis and erythropoietin production not due to hypoxia, but due to another disease such as a renal tumor
20
Q
Primary polycythemia is a diagnosis of ____________
A
Exclusion
21
Q
What is the cause of an increased hematocrit and increased total protein?
A
Dehydration
22
Q
What is the cause of an increased hematocrit and normal total protein?
A
Splenic contraction or absolute erythrocytosis
23
Q
What is the cause of an increased hematocrit and decreased total protein?
A
Severe gastroenteritis
24
Q
What is the cause of a decreased hematocrit and normal total protein?
A
Anemia not due to blood loss
25
What is the cause of a decreased hematocrit and decreased total protein?
Overhydration or anemia due to blood loss
26
What is poikilocytosis? What causes this?
This general term is used to describe any abnormally shaped RBCs. Most commonly due to artifact.
27
What is the most common cause of hyperalbuminemia?
Hemoconcentration/dehydration
28
What are echinocytes?
This term is used to describe 'spiky' looking RBCs (drying artifact)
29
What is anisocytosis?
This term is used to describe variation in RBC sizes
30
What type of erythrocytosis can hyperthyroidism cause?
Appropriate secondary erythrocytosis
31
What type of erythrocytosis can respiratory disease cause?
Appropriate secondary erythrocytosis
32
What type of erythrocytosis can heart failure cause?
Appropriate secondary erythrocytosis
33
What is hemoglobin?
A protein on the erythrocyte that carries iron that binds to oxygen.
34
How can you classify anemia?
1. Grade/severity (mild, moderate, marked)
2. Bone marrow response (regenerative or non-regenerative)
3. Cause (hemorrhage, hemolysis, hypoplasia)
4. RBC morphology
5. Etiology (blood-borne parasite, trauma, etc.)
35
What level of hematocrit is classified as severe anemia in dogs?
< 0.2
36
What level of hematocrit is classified as severe anemia in cats and horses?
< 0.15
37
What level of hematocrit is classified as severe anemia in cattle?
< 0.14
38
What is regenerative anemia?
An anemia where the bone marrow responds appropriately and increases its release of RBCs in circulation.
39
What RBC morphology is seen in regenerative anemia?
Presence of polychromatophils/reticulocytes in blood (immature RBCs).
40
What is non-regenerative anemia?
An anemia where the bone marrow does not respond appropriately by making more RBCs.
41
What RBC morphology is seen in non-regenerative anemia?
You wouldn't see any polychromatophils/reticulocytes in blood (immature RBCs).
42
How long does erythropoiesis typically take?
2-4 days
43
What is mean cell volume (MCV)?
The average volume of a RBC.
44
What is it called when your MCV is above normal parameters?
Macrocytic.
## Footnote
You'd see this if it was regenerative anemia because reticulocytes are larger than mature RBCs.
45
What is it called when your MCV is below normal parameters?
Microcytic
46
What is mean cell hemoglobin concentration (MCHC)?
The average concentration of hemoglobin per RBC.
47
What would increased MCHC be caused by?
Artifact because RBC can't physically pack any more hemoglobin inside them than they already have.
48
What do hypochromic RBCs look like?
They are paler than normal RBCs.
49
Hemorrhage and hemolysis cause __________ anemia.
Regenerative (given there has been adequate time for a bone marrow response).
50
Hypoplasia causes __________ anemia.
Non-regenerative (bone marrow hypoplasia means that it can't produce the amount of RBCs that it wants to).
51
What is different with horses regarding RBC morphology with regenerative anemia?
They do not show evidence of polychromatophils or reticulocytes.
52
How can you diagnose regenerative anemia on a CBC with horses?
You will see macrocytosis instead of reticulocytes/polychromatophils.
53
When would an animal develop iron deficiency anemia?
When there is major blood loss from the body.
54
Severe chronic iron-deficiency anemia can cause ___________cytic and _________chromic RBCs on a CBC.
Microcytic (decreased MCV) and hypochromic (decreased MCHC).
55
What are keratocytes?
"Helmet" or crescent-shaped RBCs.
56
What are schizocytes?
A fragmented part of a red blood cell.
57
What does iron-deficiency anemia do to RBC lifespan?
It decreases it. Sometimes you will also see keratocytes and schizocytes because the RBCs are more fragile.
58
If you see microcytic and hypochromic RBCs on a CBC, what should you be suspicious of?
Iron-deficiency anemia.
59
Hemolysis is most indicative of which type of anemia?
Regenerative anemia (unless it's very acute)
60
What is hemolysis?
The lysis/destruction of erythrocytes causing them to release hemoglobin
61
What RBC morphology will you see with hemolysis on a blood smear?
- Polychromasia/reticulocytosis (likely regenerative anemia)
- Spherocytes
- Ghost cells
62
Hemorrhage is most indicative of which type of anemia?
Regenerative anemia
63
IMHA is what form of hemolysis?
Both intravascular and extravascular
64
Which two clinical signs does intravascular hemolysis cause?
Hemoglobinemia (excess hemoglobin in plasma) and hemoglobinuria (excess hemoglobin in urine).
## Footnote
This is because when the RBCs burst, all the hemoglobin leaks out. In time you may also see hyperbilirubinemia and bilirubinuria.
65
When does intravascular hemolysis occur?
It occurs when complement is activated due to antibodies on surface of RBC, resulting in assembly of MAC (membrane attack complex and lysis of cell)
66
What type of irregular RBC morphology do we see with intravascular hemolysis and why?
We commonly see ghost cells because in intravascular hemolysis all the hemoglobin leaks out of the burst RBC and into the plasma, leaving behind its 'ghost' RBC shell.
67
What occurs in extravascular hemolysis?
Macrophages (mostly in spleen, liver, and bone marrow) recognize and destroy RBCs that have been targeted for destruction.
68
When does extravascular hemolysis occur?
It occurs when RBCs get flagged as abnormal by immune system and are phagocytosed by macrophages.
69
What triggers extravascular hemolysis?
The presence of self or foreign antigens on the surface of RBCs. This can be caused by the surface bound antibody in IMHA, drugs, neoplasia, hemotropic organisms such as Mycoplasma sp., shape changes in RBCs, etc.
70
What clinical signs does extravascular hemolysis cause?
Usually we see hyperbilirubinemia and bilirubinuria when EV hemolysis becomes excessive (it does NOT cause hemoglobinemia and hemoglobinuria).
71
Which occurs more frequently, extravascular hemolysis or intravascular hemolysis?
Extravascular hemolysis occurs more frequently.
72
At what location does extravascular hemolysis occur?
In the macrophages in the spleen, liver, and bone marrow.
73
At what location does intravascular hemolysis occur?
In the blood vessels.
74
What level of anemia categorizes extravascular hemolysis?
Mild to marked.
75
What level of anemia categorizes intravascular hemolysis?
Marked or rapidly falling hematocrit or PCV.
76
What is the onset of illness of extravascular hemolysis?
Days to weeks.
77
What is the onset of illness of intravascular hemolysis?
Hours to days.
78
How does hemolysis cause hyperbilirubinemia?
The hemoglobin released from the lysis of RBCs causes macrophages to break down the hemoglobin into bilirubin. If there is excess hemolysis occurring, the liver is overwhelmed (normally the liver's job is to take up, conjugate and/or excrete bilirubin). Increased plasma bilirubin will cause increased urinary excretion (bilirubinuria).
79
A bilirubin level of greater than _________ μmol/L in serum is indicative of clinical icterus.
25-35
80
What are the seven main causes of hemolytic anemia in animals?
1. IMHA
2. Oxidative damage
3. Infectious agents
4. Fragmentation of RBCs
5. Inherited RBC metabolic defects
6. Hypophosphatemia
7. Neoplasia
81
What is the main cause of primary IMHA?
Idiopathic or autoimmune.
82
What is the main cause of secondary IMHA?
It can be due to:
- Drugs/toxins
- Transfusion reaction
- Neonatal isoerythrolysis
- Infectious agents
- Neoplasia
83
What is the most common hemolytic anemia in dogs?
IMHA
84
What occurs during IMHA?
The body produces antibodies on the surfaces of RBCs for unknown reasons. This results in RBC destruction through extravascular and/or intravascular hemolysis.
85
IMHA that results in extravascular hemolysis will lead to what classic morphological RBC change? Why does this occur?
It leads to spherocytes. As RBCs are engulfed and degraded by macrophages, they may lose portions of their surface area. The loss of membrane surface area can cause the RBC to assume a more spherical shape (spherocytes).
86
What are spherocytes?
They are RBCs with a spherical shape and a loss of central pallor.
87
How are spherocytes formed?
RBCs get partially phagocytosed by macrophages which take a piece of RBC membrane. The RBC then has less surface area but the same volume.
88
What are the five classic features of IMHA?
1. Regenerative anemia
2. Appearance of spherocytes
3. Positive Coombs test
4. Presence of hyperbilirubinemia/bilirubinuria
5. Inflammatory leukogram
+/- Agglutination
+/- Ghost cells
+/- Thrombocytopenia (Evan's syndrome)
89
What is the Coombs test?
A direct antiglobulin test (DAT) that detects antibodies and complement bound to RBCs. The Coombs reagent is anti-IgG, anti-IgM or anti-complement antibody that binds to and agglutinates affected RBCs.
## Footnote
False negatives & false positives occur, thus have to be cautious with interpretation!
90
When is the Coombs test not useful in diagnosing IMHA?
It will not be useful if auto-agglutination is already present.
91
Oxidative damage can lead to what morphological RBC changes (two)?
- Heinz bodies
- Eccentrocytes
92
How does oxidative damage cause the formation of Heinz bodies?
Oxidative damage to hemoglobin causes precipitation of denatured globin portion of hemoglobin.
93
How does oxidative damage cause the formation of eccentrocytes?
Oxidative damage destroys the lipid portion of the RBC membrane (lipid peroxidation).
94
What is the most common cause of oxidative damage of RBCs in dogs?
Onions, garlic, acetaminophen (Tylenol).
95
What is the most common cause of oxidative damage of RBCs in cats?
Onions and acetaminophen (Tylenol).
96
What is the most common cause of oxidative damage of RBCs in horses?
Wilted/partially dried red maple leaves and onions.
97
What is the most common cause of oxidative damage of RBCs in cattle?
Brassica spp and onions.
98
What is the most common cause of oxidative damage of RBCs in sheep?
Copper toxicity.
99
Which seven infectious agents commonly cause hemolytic anemia?
- Mycoplasma sp. (cats, dogs, pigs, cattle, llamas)
- Anaplasma marginale (cattle)
- Babesia sp. (cattle, horses, dogs)
- Leptospira
- Clostridium
- Equine infectious anemia virus
- FeLV
100
What are two main causes of hemolytic anemia caused by RBC fragmentation?
Fibrin strand injury and turbulent blood flow.
## Footnote
(ex. DIC, hemangiosarcoma, vasculitis)
101
Hemolytic anemia caused by RBC fragmentation can lead to what morphological RBC changes (three)?
- Schizocytes (broken shards)
- Keratocytes ('crab claw')
- Acanthocytes (spiky)
102
In RBC fragmentation, hemolysis occurs primarily through the __________ mechanism.
Extravascular
103
What causes non regenerative anemia?
A lack of RBC production by bone marrow, causing erythrocyte hypoplasia
104
What is a characteristic sign of non-regenerative anemia on a blood smear or CBC?
The absence of polychromatophils/reticulocytes (immature RBCs)
105
What are the two main categories of non-regenerative anemia?
1. Intramedullary disease (disease in the bone marrow that results in erythroid hypoplasia or ineffective erythropoiesis)
2. Extramedullary disease (disease outside bone marrow that secondarily suppresses its ability to respond to an anemia or produce RBCs)
106
What are four causes of non-regenerative anemia caused by primary/intramedullary bone marrow disease?
- Acute leukemia
- FeLV infection
- Nutritional deficiency (Fe, Cu)
- Direct drug/toxin effects
107
What are three causes of non-regenerative anemia caused by secondary/extramedullary bone marrow disease?
- Anemia of inflammatory disease
- Anemia of chronic kidney disease
- Anemia of endocrine disease
108
What do we normally see on a CBC with bone marrow hypoplasia?
- Anemia can be mild to marked
- Typically normocytic and normochromic
- Other cell lines may be affected
109
What is the term for when there is a decrease in any two bone marrow cell lines?
Bicytopenia
110
What is the term for when there is a decrease in all bone marrow cell lines?
Pancytopenia (ex. decreased platelets, WBCs, and RBCs)
111
Aplastic anemia causes _____cytopenia
Pancytopenia
112
What are five causes of bone marrow hypoplasia?
1. Infectious agents (bacterial, viral, fungal, protozoal)
2. Drugs/Toxins (chemotherapy drugs, radiation, estrogen, idiosyncratic reactions causing aplastic anemia)
3. Marrow replacement (neoplasia, myelofibrosis)
4. Marrow necrosis (hypoxia, neoplasia, drug effects)
5. Immune-mediated (pure red cell aplasia)
113
What is pure red cell aplasia (PRCA)?
The decreased production of erythroid cells only in the bone marrow due to immune-mediated destruction of RBC precursors
114
What is the pathogenesis of FeLV associated non-regenerative anemia?
FeLV damages erythroid precursors which results in ineffective erythropoiesis and anemia. Defective RBCs may also be produced resulting in increased apoptosis
115
What would we see on a CBC with FeLV associated non-regenerative anemia?
- Anemia may be macrocytic
- Defective maturation therefore decreased cell divisions
- Asynchronous maturation of nucleus and cytoplasm (produces megaloblastic cells)
116
What is the most common type of non-regenerative anemia?
Anemia of inflammatory disease (AID)
117
What do we normally see on a CBC with anemia of inflammatory disease?
- Mild to moderate anemia
- Normocytic and normochromic
- Often concurrent inflammatory leukogram
- Hyperglobulinemia
## Footnote
Little clinical significance on its own - secondary to primary inflammatory disease
118
True or False: AID can occur in any disease/disorder with an inflammatory component
True
119
What is the pathogenesis of AID?
Inflammatory cytokines released will cause:
1. Decreased RBC lifespan (extravascular hemolysis)
2. Inhibition of erythropoietin production or release
3. Decreased erythropoiesis through decreased iron availability
4. Decreased iron availability leads to decreased iron absorption in GIT and iron sequestration within macrophages (because of hepcidin)
120
What is hepcidin?
A hormone produced by hepatocytes that is a key regulator of systemic iron homeostasis
121
What is the function of hepcidin?
It acts in the presence of inflammation to:
1. Block iron release from enterocytes in GI tract
2. Block iron release from macrophages recycling old RBCs
3. Block the mobilization of all stored iron
## Footnote
This is a host defense mechanism to limit extracellular iron availability to microorganisms
122
What do we normally see on a CBC with anemia of chronic kidney disease (ACKD)?
- Anemia can be mild, moderate, or severe depending on the case (PCV range can be 13-26%)
- Normocytic and normochromic
- Concurrent evidence of kidney disease (azotemia with low USG/ isosthenuria, etc.)
123
What is the pathogenesis of anemia of chronic kidney disease (ACKD)?
1. Decreased erythropoietin production due to kidney damage (specifically damage to renal tubule interstitial cells where erythropoietin is produced)
2. Decreased marrow response to erythropoietin (uremic toxins +/- inflammatory cytokines change the bone marrow environment, affecting its response to erythropoietin and ability to perform erythropoiesis)
124
What is anemia of endocrine disease?
A type of non-regenerative anemia that can be seen with hypothyroidism and hypoadrenocorticism
125
What do we normally see on a CBC with anemia of endocrine disease?
- Anemia of mild to moderate degree
- Normocytic and normochromic
- Due to decreased metabolism in hypothyroidism and subsequent decrease in O2 demand; unknown pathogenesis in Addison's disease
126
Which cause of non-regenerative anemia would show hyperproteinemia on a CBC?
Anemia of inflammatory disease (mostly hyperglobulinemia)
