Anemia Flashcards
Define anemia
a decrease in the number, volume, and/or hemoglobin content of erythrocytes
define polycythemia
an increase in the number, volume, and/or hemoglobin content of erythrocytes
clinicaly what does the term anemia mean?
low total blood hemoglobin
(this is because no matter the defect, the overall effect is a decrease in functional hemoglobin)
relative anemia
normal RBC mass
increased amount of plasma fluid
shows anemia on PCV BUT normal RBC mass
causes of relative anemia
- can be seen in newborn animals
- overhydration
absolute anemia
- a true decrease in RBC mass
- is common and clinically significant
causes of absolute anemia
- failure to produce enough RBCs (iron deficiency, bone marrow deficiency, congenital defect, neoplasia)
- RBC loss is greater than RBC production (bleeding or destruction)
clinical signs of anemia (4)
- pale mm (or yellow if RBCs are being broken down)
- reduced exercise tolerance (gradual onset lethargy)
- tachycardia
- increased respiration with exertional dyspnea (respiratory acidosis)
what is masked with hemolytic anemia?
the pale mm may be masked by icterus
what clinical signs are also seen with chronic anemia? (2)
- low-grade fever
- dry rough hair coat
why is anemia clasified in different groups?
to help identify the probable causes
what are the 3 common methods of classifying anemia
- erythrocyte morphology
- degree of bone marrow response
- cause
How are cells grouped according to the erythrocyte morphology classification?
by cell size and hemoglobin content
MCV and MCHC
what further groups can the erythrocy morphology classification be broken into?
reticulocyte count
plasma protein levels
leukocyte responce
thrombocyte counts
blood smear evaluation
Normocytic
normal sized RBC
MCV
Microcytic
decreased RBC size
MCV
Macrocytic
increased RBC size
MCV
MCV determines if the cells are:
normocytic, macrocytic, or microcytic
MCHC demonstrates that cells are:
normochromasia, hyperchromasia, or hypochromasia
hypochromic
decreased hemoglobin concentration
normochromic
normal hemoglobin concentration
hyperchromic
increased hemoglobin concentration*
spherocytes are the only true form of hyperchromasia
decreased MCHC
hypochromic
increased MCHC
hyperchromic
increased MCV
macrocytic
decreased MCV
microcytic
increased MCV; decreased MCHC
macrocytic hypochromic anemia
regenerative anemia
macrocytic hypochromic anemia (5)
- increased MCV; decreased MCHC
- regenerative anemia
- seen several days after acute blood loss or hemolysis
- indicated marked RBC regeneration
- presence of polychromatophils/ reticulocytes
decreased MCV; decreased MCHC
microcytic hypochromic anemia
iron deficiency
microcytic hypochromic anemia
- decreased MCV; decreased MCHC
- non-regenerative anemia
- indicates iron deficiency (impaired iron metabolism or iron depletion from chronic blood loss)
classifications of bone marrow response
regenerative or non regenerative
- based on the presence, absence, or degree of bone marrow proliferation evident in peripheral blood
- can be assessed through a reticulocyte count
causes of regenerative anemia
- hemorrhage
- hemolysis
regenerative anemia
- increased number of normal and immature RBCs
- normal bone marrow response
- but loss is greater than production
how long after an injury does the body START producing more RBCs
3-5 days
when is the peak response after an injury
5-6 days after
how long after an injury before complete recovery?
2-3 weeks
what do we see in the peripheral blood 5-6 days after an injury?
new cells
a few hours after blood loss what is occurring in the kidney?
- kidney sense the low oxygen levels
- releases erythropoietin to the bone marrow
- stimulating the production of RBCs
2-3 days post blood loss
- polychromasia
- decreased number of RBCs
- nRBC
very regenerative anemia will show
increased MCV; decreased MCHC
how is the degree of response to blood loss best estimated?
a reticulocyte count
how do you asses regenerative anemia in horses?
sequential PVC readings or bone marrow exams
horses with intensely regenerative anemia may show what?
anisocytosis without polychromasia
hemorrhagic anemia (6)
- cells lost due to bleeding
- moderate degree of regenerations (2-3x more than normal) due to lack/loss of iron
- the amount of iron present will affect the degree of the response (this can be judged by the presence of reticulocytes)
- in severe cases or chronic blood loss, a non-regenerative anemia due to lack of iron may result
- clear plasma
- decreased plasma proteins
Hemolytic regenerative anemia
- shortened RBC lifespan
- hemolysis may be intra- or extravascular
- iron is retained in the body and available for use
- higher regenerative response
- may have high reticulocyte count (maybe 3x normal)
- blood plasma may be icteric due to RBC breakdown
- may have normal to slightly increased plasma protein
- blood smear may show: polychromasia, nRBCs, schistocytes, spherocytes, and other (parasites, agglutinations)
types of regenerative anemia (3)
- hemorrhagic anemia
- hemolytic anemia
- heinz body anemia
Heinz body anemia
- regenerative anemia
- denatured hemoglobin due to oxidative injury
-possible causes: the spleen may destroy the RBCs with the heinz body causing anemia OR intravascular hemolysis - cats normally have more heinz bodies because their hemoglobin is more unstable, is normal cell aging
hemorrhagic hematocrit tube
- clear serum
- proportional loss of everything (just less blood)
hemolytic hematocrit tube (2)
- serum commonly icteric (because of RBC breakdown)
- normal protein levels or slightly decreased
causes of non-regenerative anemia
- primary bone marrow failure
- secondary bone marrow failure
non-regenerative anemia
- insufficient bone marrow response
- can be due to: lack of RBC production, primary intrinsic bone marrow failure, lack of nutrients, lack of erythropoietin stimulation
- seen in the first 2-3 days after hemorrhage or hemolysis
- diagnosed by bone marrow exam for differentiation
- poikilocytes, anisocytes
- decreased MCV and decreased MCHC
causes of non-regenerative anemia (4)
- maturation defect or hypoproliferative anemia may be due to primary bone marrow failure
- nutrient deficiency (iron, protein, b-vitamins, folic acid)
- malabsorption
- chronic blood loss
Primary bone marrow failure
- non-regenerative anemia
- aka hypoplastic or aplastic anemia
- due to: bone marrow infections, toxins, neoplasia, exhaustion from overstimulation
secondary bone marrow failure
- non-regenerative anemia
- bone marrow failure due to disease process outside the bone marrow
- nutrient deficiency (iron, protein, vitamin b)
- malabsorption
- chronic blood loss
how to treat non-regenerative anemia? (3)
- treat the underlying cause
- supportive care until the bone marrow kicks in
- restore blood volume and RBC numbers
what can polycythemia also be called?
erythrocytosis
define polycythemia
an increase in the RBC count, Hg content, and/or volume
at what RBC mass (PCV) does tissue oxygenation start to diminish rapidly?
at 50% and above
polycythemia is a change in:
- the RBC itself
- the mass of circulating RBCs
- erythropoietin tissue of the bone marrow
how does the number of RBCs affect blood thickness?
as number increases thickness increases
what does an increase in blood thickness do to vascular resistance?
- increases pulmonary and vascular resistance
bc: sluggish blood flow, reduced cardiac output, decreased tissue oxygenation
absolute polycythemia
- very rare
- can be seen as a primary or secondary condition
- is a true increase in the number of RBCs without a change in the total blood volume
- can be seen in dogs, cats, and cattle
- no change in RBC morphology
primary absolute polycythemia
- aka polycythemia vera
- is a rare abnormality of the bone marrow (unregulated overproduction of RBCs in the bone marrow)
- no morphological changes
- mild increase in WBC and platelets
- as volume increases there’s: elevated BP, vascular damage, blood clot formation
- blood is: normocytic and normochromic. increased PCV, RBC, MCV, MCHC
- typically genetic
when is polycythemia an appropriate response
in response to hypoxia and erythropoietin stimulation to compensate for a disease that has reduced oxygenation of the tissue (eg. pneumonia or heart disease)
(kidney releases erythropoietin to stimulate RBC production)
when is secondary polycythemia an inappropriate response?
for renal disease and neoplasia
when is polycythemia a physiological response?
when animals are moved to a higher elevation
which polycythemia is more common and significant?
relative polycythemia
define relative polycythemia
the total mass of RBC is constant but appears elevated
- loss of liquid or plasma (hemoconcentration)
- increased ratio
transient relative polycythemia
- the release of stored RBCs due to stress, excitement, exercise
- the RBCs stored in the spleen and bone marrow are released
why might there be hemoconcentration? (3)
- dehydration
- fluid shifts
- mass of RBC remains constant
what can cause hemoconcentration?
- vomiting
- diarrhea
- polyuria
- excessive sweating/ panting
- water deprivation
- fluid shift (heart or lung disease, vascular pooling [ie shock])
- really bad kidney disease
what is the most common cause of polycythemia?
hemoconcentration
relative polycythemia, hemoconcentration and its effects on tissue oxygenation
- PCV>50% = decreased capillary circulation and tissue oxygenation
- most common reason to see this is hemorrhagic gastroenteritis
what is the most common reason to see hemoconcentration relative anemia in the ER?
hemorrhagic gastroenteritis
types of relative polycythemia (2)
- transient
- hemoconcentration
treatment options for transient relative polycythemia?
- should correct itself
treatment options of hemoconcentration relative polycythemia
- gradual rehydration
- treat the cause
treatment for absolute polycythemia
- reduce the viscosity (either decrease the mass of RBCs or increase the fluid portion of the blood)
- phlebotomy
- medications that suppress RBC production (hydroxyurea, chemotherapy)
how to treat absolute polycythemia
- treat the underlying cause
