Classification of anemia Flashcards
Findings that denote regeneration are:
a) Polychromasia
b) Reticulocytosis
c) Hypercellular bone marrow and a low M/E ratio (if WBC normal or increased)
Regenerative (responsive) anemia
in bone marrow
- Bone marrow actively responding - increasing its production of RBCs
- Ability to respond — primarily pathologic effect is extra marrow, i.e. hemorrhage or hemolysis
Nonregenerative Anemia
in bone marrow
- Bone marrow unable to respond; therefore primary pathologic state in
the bone marrow - Polychromasia and reticulocytosis absent; bone marrow exam is
indicated
Classification According to Pathophysiologic Mechanism
A. Blood loss (hemorrhagic) anemias
B. Anemias caused by accelerated RBC destruction (hemolytic)
C. Anemias caused by decreased or defective erythropoiesis
Clinical Signs of Anemia
- Pale mucous membranes
- Weakness/loss of stamina
- Tachycardia/polypnea-especially after exercise
- Hypersensitivity to cold
- Heart murmur—decreased viscosity and increased turbulence of the blood
- Shock if 1/3 of blood volume is lost in a short period
- Icterus, hemoglobinuria, hemorrhage, or fever depending pathophysiologic mechanism involved
B. Signs are less marked if onset is gradual and the animal can adapt to decreased RBC
Laboratory Confirmation of anemia
A. PCV– easiest, most accurate. Interpret with knowledge of hydration state and any alteration by splenic contraction
B. Hemoglobin concentration and RBC count used to further classify the anemia
Regenerative Anemia
- suggests either blood loss or RBC destruction mechanism of sufficient duration (2-3 days) for response to be evident
- Bone marrow exam rarely necessary (erythropoietic hyperplasia should be evident) – best means of detecting regenerative anemia in the horse
- A regenerative response is seen in recovery stage of non-regenerative anemia also
Non-regenerative Anemia
- Suggests a bone marrow disorder (or kidney disorder)
2. Bone marrow exam indicated to confirm and classify the anemia
3. Anemia caused by peracute or acute hemorrhage or hemolysis may present a non-regenerative pattern first 2-3 days after onset
Blood Loss (Hemorrhagic) Anemia
A. Findings include:
1. Clinical signs of hemorrhage (may be occult) 2. Regenerative response (after 2-3 days) 3. Decreased plasma protein concentration if hemorrhage external
Differential Features Of External vs. Internal Hemorrhage
- External - prevents reutilization of components (Fe, PP). These reabsorbed during internal hemorrhage. (GI bleeding is external)
- Internal - About 2/3 RBCs in body cavities are reabsorbed into lymphatics (completed in 24-72 hours) and 1/3 are lysed or phagocytized; Fe and PP are reutilized
Characteristics of Acute Blood Loss
- Clinical signs depend on amount of blood lost, period of time, site of hemorrhage
- PCV initially normal (all blood components lost in equal proportions). May be in hypovolemic shock.
- Splenic contractions delivers high PCV blood (80%) – may transitorily increase PCV
- Platelet numbers usually increased in the first few hours; may be decreased if consumption extensive
- Increased neutrophils commonly occur about 3 hours post-hemorrhage
- Blood volume restored by addition of interstitial fluid starts within 2-3 hours after onset and proceeds 48-72 hours Dilution of RBCs –lab signs of anemia, TPP concentration also decreased
- Signs of increased RBC production (polychromasia, reticulocytosis) evident by 48-72 hours; maximum 7 days after
- Availability of iron determines magnitude of reticulocytosis. Retic numbers only 4-5x normal in acute hemorrhage – slow release of iron from stores. (Greater in hemolytic anemias – iron reutilized directly.) Therefore, retics higher in internal versus external hemorrhage.
- Hemogram back to normal 1-2 weeks following a single acute hemorrhage episode.
If increased retics > 2-3 weeks, continuous bleeding suspected.
Characteristics of Chronic Blood Loss
- Anemia develops slowly – no hypovolemia
- PCV can reach low values before clinical signs appear – physiologic adaptation
- Regenerative response and hypoproteinemia usually observed
- Body stores of iron may be depleted – iron-lack anemia may develop. Then regenerative signs less pronounced. Poikilocytosis commonly present at this stage
- Iron-lack anemia develops more readily in young animals – less storage iron
- Bone marrow response may end abruptly in prolonged cases – non-regenerative iron-lack anemia
Accelerated Erythrocyte Destruction (Hemolytic Anemia)
- Regenerative response. Reticulocyte counts higher because iron readily available from destroyed RBCs.
- Normal plasma protein conc.
- Neutrophilic leukocytosis; monocytosis may also occur
- Absence of clinical signs of hemorrhage
- Hyperbilirubinemia, etc. if destruction of sufficient magnitude to exceed the conjugating capacity of the liver
Detection and Characteristics of Anemia resulting from Intravascular Hemolysis
Most cases peracute or acute
Regenerative response may not be evident (2-3 days required)
Hemoglobinemia -Key feature – intravascular hemolysis
a. Increased MCHC
b. Red discoloration of plasma
c. Hemoglobinuria
Hyperbilirubinemia and
icterus occur if :
a. Hemolysis of sufficient
duration for bilirubin to
be formed
b. Bilirubin formation sufficient
magnitude to exceed the capacity of
the liver to conjugate it
