Week 3: Hematologic Pathophysiology Anemias Flashcards
1
Q
Definition of Erythrocyte
A
a red blood cell
2
Q
Definition of a Reticulocyte
A
immature erythrocyte (day 1 or 2 in the blood steam)
3
Q
Definition of Anemia
A
deficient number of RBCs
4
Q
Definition of Mean Corpuscle Volume
A
size
5
Q
Definition of Normocytic
A
normal sized cell
6
Q
Definition of Microcytic
A
smaller than normal size cell
7
Q
Definition of Macrocytic
A
larger than normal size
8
Q
Definition of Hemoglobin
A
four folded globin chains (2alpha 2 beta)
9
Q
Definition of Hemolytic anemia
A
abnormal hemolysis (breakdown) of RBCs
10
Q
Symptoms of Anemia
A
fatigue pallor hypoxia exercise intolerance syncopy hypovolemia/hypotension irregular heart rate SOB chest pain
11
Q
Primary Function of an RBC
A
to transport hemoglobin
transport oxygen to tissue
12
Q
1 gram of Hgb can combine with
A
1.34ml of oxygen= 100% saturdation
13
Q
What is the enzyme in RBCs and what is its function?
A
carbonic anhydrase
catalyzes reaction between CO2 and H2O to form carbonic acid, H2CO3
14
Q
How is CO2 transported to lungs?
A
in the form of HCO3- to be removed
15
Q
How is erythropoietin stimulated?
A
any condition that decreases oxygen transport to tissues
a glycoprotein formed in the kidneys
16
Q
Why do you have elevated reticulocytes in pathological states?
A
Reticulocytes are immature blood cells, in pathological cases RBCs are needed. Therefore a positive feedback loop occurs releasing reticulocytes from bone marrow
17
Q
What is the main adverse effect of anemia?
A
decreased oxygen-carrying capacity
18
Q
WHO definition of anemia
A
Hb concentration less than 12 g/dl for women and less then 13g/dl for men
19
Q
What causes pregnancy “physiologic anemia”?
A
due to decreased Hct in relation to increased plasma volume
20
Q
What is polycythemia?
A
increase in circulating RBCs
21
Q
What is the main adverse effect of polycythemia?
A
increase in blood viscosity
22
Q
What are the main causes of anemia?
A
blood loss
decreased production
increased destruction
23
Q
What are the two types of blood loss anemia?
A
acute blood loss and chronic blood loss
24
Q
What is acute blood loss?
A
the body replaces fluid portion of plasma in 1-3 days
leaving low concentration of RBCs
25
What is chronic blood loss?
cannot absorb enough iron from the gut to make Hgb as rapidly as it is lost
RBCs are produced much smaller and have little Hgb inside- microcytic anemia
26
What is the 10/30 rule?
transfuse if the Hb level is less then 10g/dl or Hct is <30%
| no evidence that Hb levels below this level mandate transfusion
27
What is the transfusion trigger?
Hb levels below 6g/dl will benefit from transfusion
28
Risks associated with Transfusion
```
infections and immunomodulatory effects
Hep B, Hep C, HIV
cancer re-occurance
bacterial infections
transfusion related acute lung injury (TRALI)
hemolytic transfusion reactions
```
29
EBL <15%
rarely requires transfusion
30
EBL 30%
replacement with crystalloids/ albumins
31
EBL 30-40%
RBC transfusion
32
EBL>50%
massive transfusion
| may need accompanied with FFP and platelets (1:1:1)
33
What are the four types of anemia based on mechanism?
decreased production
increased destruction (life span <120 days)
Blood loss
infectious
34
What are examples of anemia from decreased production? (2)
iron deficiency
| autoimmune
35
What are examples of anemia from increased destruction? (3)
thalassemia
hemolytic anemia
sickle cell
36
What are examples of anemia from blood loss? (2)
acute
| chronic
37
What are examples of anemia from infectious processes? (3)
malaria parasite destroys RBCs
babesia (parasite usually spread by ticks) causes RBC hemolysis
Parvovirus (fifth disease) virus inhibits erythropoiesis
38
What are three types of anemias based on morphology?
microcytic
normocytic
macrocytic/megaloblastic
39
What is microcytic anemia? Causes?
mean corpuscular volume <80fL
iron deficiency
thalassemia
40
What is normocytic anemia? Causes?
mean corpuscular volume 80-100fL
sickle cell anemia
chronic kidney disease, acute blood loss, aplastic anemia
G6PD deficiency
41
What is macrocytic/ megaloblastic anemia? Causes?
defects in nuclear maturation
folic acid and vitamin B12 deficiency
liver disease, alcoholism
42
How do you treat iron deficiency anemia?
oral iron: if elective surgery can be postponed for 2-4 months to allow for correction
IV iron- urgent surgery within a few weeks
RBC transfusion
43
How long do you need to continue oral iron supplements?
1 year after the source of blood has been corrected
44
What is hemolytic anemia?
accelerated destruction of RBCs
removed to quickly or lysed to early
RBC life <120 days
45
What will you find in blood test for hemolytic anemia?
increased immature reticulocytes
unconjugated hyperbilirubinemia/jaundice
increased lactate dehydrogenase (an enzyme released from lysed RBCs)
decreased haptoglobin (a plasma protein that binds free hemoglobin)
46
What is sickle cell anemia?
autosomal recessive disorder caused by a single amino acid substitution in beta globin that creates sickle hemoglobin
47
What is the most common familial hemolytic anemia?
sickle cell anemia
48
What is sickle cell anemia protective against?
malaria
49
Pathogenesis of Sickle Cell anemia
mutation in beta globin that leads to the polymerization of sickle hemoglobin (HbS) into long, stiff chains when it is deoxygenated
50
What is the most important variable that determines whether HbS-containing red cells undergo sickling is
the intracellular concentration of other hemoglobins
51
HbA
normal hemoglobin
52
HbF
fetal hemoglobin
53
What are consequences of Sickling RBCs?
chronic hemolytic anemia
ischemic tissue damage with episodic pain
spleen auto infarction
54
What microvascular is affected in sickling RBCs?
acute chest syndrome
joints
strokes
retinal damage
55
Treatments for Sickle Cell
hydroxyurea
| stem cell transplants
56
How does hydroxyurea help?
raises HbF levels
| anti-inflammatory
57
What is autoimmune anemia or autoimmune hemolytic anemia?
antibodies IgG and IgM are directed against a person's own RBCs
RBCs lifespan is severely decreased
58
What are causes of autoimmune anemia?
idiopathic
leukemias
infectious (mononucleosis)
drug-induced (pencillins, quinidine)
59
What is the treatment to autoimmune anemia?
immunosuppressants and steroids
60
Describe hemolytic disease of the newborn
incompatibility between mother and the fetus
erythroblastosis fetalis
fetus inherits red cell antigenic determinants from the father that are foreign to the mother
fetal red cells can enter maternal circulation during 3rd trimester and childbirth this sensitizes mother to paternal red cell antigens and leads to productoin of IgG anti-D red cell antibodies that cross the placenta and cause hemolysis of fetal red cells
61
Fetus has what antigen and mother is?
fetus is RhD antigen positive and mother is RhD antigen negative
62
Rh Factor
a protein found on the surface of red blood cells
63
Glucose 6 phosphate dehydrogenase deficiency
X linked genetic disease from the lacking of enzyme, G6PD which is involved in the pentose phosphate pathway
64
What is the 1/2 life of RBCs with G6PD?
60 days
65
Why does hemolysis occur with G6PD?
the inability of G6PD RBCs to protect itself from oxidative damage
66
What can precipitate G6PD?
infection
DKA
medications
fava bean
67
Peripheral smears of G6PD
bite cells
68
Oxidative stress is
transient hemolysis with persistent infection or drug exposure, because lysis of older cells leaves younger cells with higher levels of G6PD that are resistant to oxidant stress
69
What are drugs can induce oxidative stress?
```
metoclopramide
penicillin and sulfa
methylene blue
hypothermia
acidosis
hyperglycemia
infection
```
70
Treatment of G6PD is
no cure
avoid triggers
treat hemolytic episodes with hydration and blood transfusions
71
How do you develop polycythemia?
sustained hypoxia results in compensatory increase in RBC mass and Hct
72
What is significant polycythemia? why?
Hct >55-60%
threatens vital organ perfusion
at risk for DVT/ arterial thrombosis
73
What is relative polycythemia?
concentrated Hct
74
what can cause relative polycythemia?
dehydration, diuretics and vomitting
75
Where does Physiologic Polycythemia occur?
natives who live at altitudes of 14,000-17,000 ft
| atmospheric o2 is low
76
What is the RBC count in physiologic polycythemia compared to normals?
rises approximately 30% compared to non-extreme altitude
77
What causes secondary polycythemia?
due to hypoxia (cardiac disease including congenital heart with R to L shunts and low CO) and pulmonary disease (extreme obesity/ pickwickian syndrome)
due to renal disease
surreptitious use of erythropoietin by high performance athletes
78
What is polycythemia vera?
stem cell (or myeloproliferative) disorder in which Hct may be as high as 60-70% instead of normal 40-45%
mutation in JAk2 gene (lacks ability to halt production of RBCs when enough present)
produces excess erythrocytes and number of platelets and leukocytes may also be increased
79
when do most symptoms of polycythemia vera present?
6-7th decade of life
80
what are the symptoms of PCV?
cyanosis, headache, dizziness, gastrointestinal symptoms, hematemesis, and melena
81
What are the effects of PCV?
total blood volume increases
viscous and engorged vessels
blood passes sluggishly through skin capillaries and a greater amount becomes deoxygenated resulting in bluish/ruddy appearance
82
What is seen in 10% of PCV patients?
marrow fibrosis
83
Treatment of PCV
```
death from vascular complications occurs within months
minimize thrombosis risk
avoid dehydration
phlebotomy
myelosuppressive drug
ruxolitinib
```
84
Anesthesia and PCV
at risk for thrombosis (reduce Hct prior to surgery)
hydration NPO status vs IV fluids
continue hydroxyurea
