49 and 50 - RBC Pathology I and II Flashcards
1
Q
What is erythropoiesis?
A
- Production or RBCs in bone marrow
- This process depends on the release of erythropoietin from the kidneys
2
Q
What are reticulocytes?
A
Immature RBCs (erythrocytes) - final stage before full maturation -
3
Q
What is the general stage before reticulocytes?
A
Normoblast
This includes three maturation stages - basophilic, polychroma and orthochromatophilic
4
Q
What stain do you use to distinguish reticulocytes from mature erythrocytes?
A
Methylene blue
5
Q
What does methylene blue stain show us?
A
Dark blue thread-like material in the reticulocyte that represents residual RNA filaments and protein - identifies the cell as a reticulocyte and not a mature erythrocyte
6
Q
What does the reticulocyte count or “retic count” tell us about a patient?
A
Reticulocytes are a marker of effective erythropoiesis, so an elevated reticulocyte count will indicate the bone marrow’s response to anemia
7
Q
How do we report retic count?
A
As a percentage
8
Q
What is normal for the retic count?
A
0.5 - 1.5%
9
Q
Describe why we would need to “correct” for the actual retic count and not just look at the reported retic count?
A
This would be the case in an anemic patient
- The initially reported retic count needs to be corrected for the degree of anemia
10
Q
What is the equation for correcting the retic count?
A
CRC = Corrected retic count RRC = Reported retic count Hct = Hematocrit 45 = Normal hematocrit
CRC = (patient Hct/45) x RRC
Example: Hct = 15%, RRC = 18%
CRC = (15/45) x 18 = 6%
The CRC is 6%, which is still high, but not as high as was initially reported
11
Q
What is a normal reticulocyte count?
A
It depends on the lab…
- Some say 0.5-1.5%
- Some say less than 3%
12
Q
What would a high reticulocyte count be?
A
10%
This indicates ANEMIA
13
Q
What is the shape of an erythrocyte?
A
Biconcave disc
14
Q
What does anisocytosis mean?
A
Anisocytosis - the patient’s RBCs are of unequal size
15
Q
What does poikilocytosis mean?
A
Poikilocytosis - the presence of abnormally shaped RBCs
16
Q
What does normocytic mean?
A
Nocmocytic - normal sized RBCs
17
Q
What does normochromic mean?
A
Normal amount of Hb
- Zone of central pallor (white dot in the center of each RBC) is approximately 1/3 the total diameter of the RBC
18
Q
What are macrocytic RBCs?
A
If the cell is larger than the average RBC, it is known as a MACROcytic cell
19
Q
What are microcytic RBCs?
A
If the cell is smaller than the average RBC, it is known as a MICROcytic cell
20
Q
What are the two ways in which you can classify an anemia?
A
- On the basis of etiology
- On the basis of MCV (mean corpuscular volume)
21
Q
Describe the classification based on etiology
A
Etiology
- Blood loss
- Impaired production
- Increased destruction
22
Q
Describe the classification based on mean corpuscular volume
A
- Microcytic = If the RBC is less than 80 fL, we say microcytic
- Normocytic = If the RBC count is 80-100 fL we say it is normocytic
- Macrocytic = If the RBC is over 100 fL, we say macrocytic
23
Q
If you are suspecting anemia, what do you do?
A
Order a complete blood count (CBC)
24
Q
What are the components of a CBC?
A
Need to understand all of this
- Hb = hemoglobin
- Hct = hematocrit
- PCV = packed cell volume
- RBC = RBC count
- MCV = mean corpuscular volume
- MCH = mean corpuscular hemoglobin
- MCHC = mean corpuscular hemoglobin concentration
- RDW = red cell distribution width
- WBC = white blood cell count
- TLC = total leukocyte ocunt
- Diff = differential leukocyte count
- Platelet count
- Evaluation of PBS (peripheral blood smear)
25
What is the normal Hb in males and females
Female: 11-15
Male: 12-16
26
What other lab values other than a CBC would you order?
- Reticulocyte count to assess erythropioetic activity
- ESR (erythrocyte sedimentation rate) to give a clue on the underlying organic disease
- Bone marrow exam when you can't determine the cause of the anemia
27
What are reticulocytes?
- Newly released RBCs from bone marrow
- Using special stains such as methylene blue, reticulocytes stain with dark blue thread-like filaments or granules (RNA) in the cytoplasm
- Within 24 hours they become RBCs
- RBCs will evenly stain a pale blue color
28
What is the MOST COMMON CAUSE of MICROcytic anemia?
********
Iron deficiency
*********
29
What is the 2nd most common cause of MICROcytic anemia?
*****
Anemia of chronic disease
*****
30
What are the other causes of MICROcytic anemia?
3rd = thalassemia
LEAST COMMON = sideroblastic anemia
***
31
What are the laboratory tests you would want to run for MICROcytic anemia?
- Serum iron
- Serum total iron binding capacity [TIBC]
- % Saturation [serum Fe/RIBC] x 100
- Serrum ferritin
- Hb electrophoesis
Basically, all you need to know is that you need more tests to confirm that it is a MICROcytic anemia
32
What are the three classifications of immune hemolytic anemias?
This means that they are immune mediated anemias due to antibodies destroying RBCs
- Drug-induced
- Auto-immune
- Allo-immune
33
Describe an autoimmune hemolytic anemia
- Lupus is the most common auto-immune hemolytic anemia (systemic lupus erythematosus)
- Female predominance
- Two types (warm or cold)
34
What is the warm type?
IgG antibodies
70% are the warm type
35
What is the cold type?
IgM antibodies + complement
30% is the cold type
36
Describe an alloimmune hemolytic anemia
Can occur due to
- Hemolytic transfusion reaction
- Hemolytic disease of newborns
37
What are the two tests you can do to determine if an immune reaction is taking place
- Direct Coombs test (DCT)
| - Indirect Coombs test (ICT)
38
What is a direct Coombs test (DCT)?
- Also know as a direct antiglobulin test (DAT)
| - Uses the patients RBCs to determine if an immune reaction against the RBCs is occuring
39
What is an indirect Coombs test (ICT)?
- Also called an indirect antiglobulin test (IAT)
| - Uses the patients serum to determine if an immune reaction against the RBCs is occurring
40
What is agglutination?
One of the methods of physically seeing red blood cell antigen-antibody reactions
It is an immunohematology test
41
What do you NEED to know in summary of immune testing?
*****
DAT and IAT are used to detect RBC antibodies on RBC and in the serum respectively
DAT is used to determine whether patients with hemolysis have an immune etiology
IAT is used to identify clinically significant red cell alloantibodies that are important in choosing compatible blood products
******
42
What is anemia?
- Anemia is decreased red cell mass affecting tissue oxygenation
- Practically defined as a low Hb or low Hct (hematocrit)
- Anemia is a sign of an underlying disease process rather than an actual specific diagnosis
43
Describe what the three etiologies of anemia classifications are again
***
Anemia etiological classification
- Increased blood loss
- Impaired RBC production
- Increased RBC destruction
44
What are the two forms of increased blood loss causing anemia?
- Acute (i.e. trauma)
| - Chronic (i.e. lesion of GI tract, gynecological disturbance, etc.)
45
What types of things would cause impaired RBC production?
- Inherited genetic defect
- Nutritional defect
- Erythropoietin deficiency
- Immune-mediated injury of progenitor cells
- Inflammation-induced iron sequestration
- Primary hematopoietic neoplasm
- Space occupying marrow lesions
- Infection of RBC progenitors
You are not going to be tested on this, just have a general idea
46
What are the types of inherited etiologies that cause increased RBC destruction?
Inherited conditions
- RBC membrane disorders
- Enzyme deficiencies
- Hemoglobin abnormalities
I don't think you'll be tested on this either, just have a general idea
47
What are the types of acquired etiologies that cause RBC destruction?
- Deficiency of PIGA
- Antibody mediated
- Mechanical trauma to RBCs
Didn't even go over this slide
48
What does a NORMAL RBC smear look like?
Peripheral Blood Smear (PBS)
- Cells are not piled up
- Normochromic
- Minimal poikilocytosis
- Minimal anisocytosis
- Nothing "weird" going on
49
Describe how the cell should not be piled up
Not piled up
- Just barely touching in the "zone of morphology"
- A few fields in from the "feathery edge" of a peripheral blood smear
- The edge is opposite to the thick end of the smear
50
Describe normochromic
Normal amount of Hb
| - Zone of central pallor (white dot in the center of each RBC) is approximately 1/3 the total diameter of the RBC
51
Describe minimal poikilocytosis
Most are a nice round shape
52
Describe minimal anisocytosis
Most are pretty much the same size
53
Describe nothing weird going on
- No nucleated RBCs
- No infectious organisms (malaria) within the RBC
- No iron aggregates
- No Howell-Jolly bodies
54
Describe hyper and hypochromic RBCs
Hyperchromic
- Cells without a central pallor (white spot) are referred to as hyperchromic
Hypochromic
- Pale cells where the central pallor is more than 1/3 the diameter are referred to as hypochromic
55
What is polychromasia?
Many colors
- Alteration in the color of the RBCs
- This is a sign of cellular immaturity
- The polychromatic RBCs are characterized by their large size and their bluish hue due to their content in RNA
56
What is normoblastemia?
THe presence of nucleated RBCs in a PBS
Indicates a hemolytic anemia
57
What are spherocytes?
****
NEED TO KNOW
| - Red blood cells which are smaller and denser than their normal counterparts
58
What are the two causes of spherocytes being present in the PBS?
****
NEED TO KNOW *****
- Hereditary spherocytosis
- Autoimmune hemolytic anemia
MEMORIZE THESE TWO ***
59
What are schistocytes?
***
NEED TO KNOW
- a fragmented part of a red blood cell
- looks like a little chip off a RBC
60
What are the two causes of schistocytes being present in a PBS?
****
NEED TO KNOW
- Microangiopathic hemolytic anemia (DIC, TTP, HUS)
- -> DIC = disseminated intravascular coagulation
- -> TTP = thrombotic thrombocytopenic purpura
- -> HUS = hemolytic uremic syndrome
- Other hemolytic anemias
61
When you compare the two conditions that cause spherocytes and schistocytes, what do you notice?
If someone is diagnosed with a hemolytic anemia, it is possible that you would see both spherocytes and schistocytes ****
62
What is basophilic stippling? What causes it?
- AKA punctate basophilia
- Little small purple dots in RBCs
- They are caused by severe anemia caused by lead poisoning, severe infection, drug exposure and alcoholism
- THINK LEAD POISONING
The lead poisoning is a board preferred question
63
What are Howell-Jolly bodies?
***
- Howell-Jolly bodies are red cell inclusions which are residual nuclear fragments
- H-J body is purple dot which is much larger than basophilic stippling
- Indicates the absence of a spleen or hemolysis
****
64
What are the three conditions you would see howell-jolly bodies in?
****
- Hemolysis
- Megaloblastic anemia
- Post-splenectomy
*****
KNOW THE THREE CONDITIONS ****
65
Reminder: BECAUSE IT IS SO IMPORTANT...
What is the first and second most common causes of microcytic anemia?
*********
MOST COMMON = iron deficiency
2nd most common = anemia of chronic disease (ACD)
**********
66
What is the pathogenesis of microcytic anemia?
Microcytic anemias are defects in the synthesis of Hb
(Hb = heme + globin chains) - something goes wrong in this process
That means that there is either something wrong with heme synthesis or the globin chains
67
Describe the defects in heme synthesis that lead to microcytic anemia
Defects in heme synthesis
- Iron deficiency
- Anemia of chronic disease
- Sideroblastic anemia
(Remember, heme is made from iron plus proto-porphyrin)
68
Describe the defects in synthesis of globin chains (alpha and beta)
Alpha and beta thalassemias
69
What will iron deficiency anemia look like on a PBS?
- Microcytic
- Hypochromic
Reticulocytes may also be present
70
Describe how you determine the properties of RBCs in iron deficiency anemia
Microcytic
- You can use the nucleus of a lymphocyte to gauge how normal the RBC size is - a normal RBC is about the same size as a lymphocyte nucleus, so if it is smaller, the RBC is microcytic
Hypochromic
- If the central pallor is more than half the diabeter of the whole cell
Reticulocyte
- If the cell is actually larger than a normal RBC, it may represent a reticulocyte
71
How do we define MACROcytic anemia?
MCV greater than 100 fL
72
What are some common causes of MACROcytic anemia?
Common causes
- Vitamin B12 or folate deficiency
- Alcohol use
- Liver disease
- Reticulocytes
Uncommon causes
- Myelodysplastic syndrome
- Hypothyroidism
73
Describe the pathogenesis of MACROcytic anemia
- Defective DNA synthesis (due to a B12 or folate deficiency) occurs
- This leads to an increase in the RBC membrane from lipid alterations associated with alcohol use
74
What is the other type of anemia other than micro and macrocytic?
Normocytic
(80-100 fL)
Don't need to know the details, just know that it exists
75
Describe anemia due to acute blood loss
- The effects are due to a loss of intravascular volume
- There is a shift of water from the interstitial fluid compartment into the vasculature within 24-48 hours
- Hemodilution occurs (watery blood) which reduces the PCV (packed cell volume) and reduces O2 in the blood
- The reduced oxygen levels stimulate erythropoietin
- Erythropoietin stimulates erythroid hyperplasia in the bone marrow
- Reticulocytes will appear in the peripheral blood after 5 days
76
What can happen in massive blood loss?
Cardiovascular collapse, shock and death
77
Describe blood loss in terms of internal and external
External blood loss
- i.e. Peptic ulcer
- May result in iron deficiency
Internal blood loss
- i.e. ruptured abdominal aortic aneurysm
- Iron is recaptured
78
What do the clinical effects of blood loss depend on?
- Rate of hemorrhage
| - Whether the bleeding is internal or external
79
Describe a clinically important clinical situation regarding internal blood loss
CRITICAL THING – if you have a car accident or trauma, the spleen can be easily broken, need to do a CT and it might only be bleeding a little, but in the next 24-48 hours is can start bleeding a lot
80
A 52 year old female complains of worsening fatigue for several weeks. A CBC is done and she has a low red blood cell count and low hemoglobin and hematocrit levels. The next value to look at on the CBC to try to differentiate the possible type of anemia she may have is
```
A. packed cell volume (PCV)
B. red cell distribution width (RDW)
C. mean corpuscular volume (MCV)
D. mean corpuscular hemoglobin (MCH)
E. mean corpuscular hemoglobin concentration (MCHC)
```
C. mean corpuscular volume (MCV)
*****
81
A cell pointed by the arrow shown below has been found in PBS in a patient with anemia. Which of the followings is the most likely diagnosis? (smaller darker RBC)
```
A. Iron deficiency anemia
B. Hereditary spherocytosis
C. Sideroblastic anemia
D. Thalassemia
E. VitB12 deficiency anemia
```
B. Hereditary spherocytosis
****
