What important information from a history can help you diagnose the cause of an anemia?
prior drug administration exposure to toxic chemicals or plants family or herd occurrence recent transfusion or colostrum ingestion age at onset of anemia
Physical findings associated with anemia
pale MM weakness, loss of stamina, exercise intolerance tachycardia and tachypnea, esp. after exercise cardiac murmur secondary to increased blood turbulence shock if rapid severe hemorrhage occurs icterus, hemoglobinuria, hemorrhage, or fever - depending on dz present
Normal HCT with low TPP leads you to what DDX?
GI protein loss proteinuria liver dz
Normal HCT with high TPP leads you to what DDX?
increased globulin synthesis dehydration masked anemia
High HCT with low TPP leads you to what conclusion?
protein loss combined with relative or absolute erythrocytosis
High HCT + High TPP = ?
Low HCT + low TPP =?
substantial ongoing or recent blood loss, overhydration
High HCT + normal TPP =
splenic contraction absolute erythrocytosis dehydration masked hypoproteinemia
low HCT + normal TPP =
increased erythrocyte destruction, decreased erythrocyte production, chronic hemorrhage
low HCT + high TPP =
anemia of inflammatory dz multiple myeloma lymphoproliferative dz
How do you classify an anemia as regenerative or non regenerative?
absolute reticulocyte count increased increased polychromasia on blood film marrow evaluation
What are the size and color classifications of anemia?
microcytic (MCV below reference), normocytic (MCV in reference), macrocytic (MCV above reference) hypochromic (MCHC below reference), normochromic (NO hyperchromic)
T/F hemodilution is a true anemia
T/F severity can rule in or out a specific cause of anemia
T - ie. severe anemia should not be attributed alone to anemia of inflammatory disease
What are the four pathophysiologic mechanisms of anemia?
blood loss or hemorrhage accelerated erythrocyte destruction (hemolysis) reduced/defective erythropoiesis hemodilution (not really an anemia)
expansion of vascular space - pregnancy, growth (plasma volume expansion, dilution from colostrum, destruction of fetal RBCs, decreased production of erythropoietin in first few months of life) overhydration splenic sequestration - splenomegaly, anesthesia, heparin treatment in horses
Which species is not ideal for a bone marrow evaluation?
What does regenerative anemia look like on blood films?
increased polychromasia increased anisocytosis metarubricytosis increased howell-jolly bodies basophilic stippling ONLY increased polychromasia is a valid indicator of regeneration - all else associated with but not indicator
Why would an acute hemorrhagic or hemolytic anemia initially appear non-regenerative?
because it takes bone marrow 3-5 days to respond to an anemia
What are features that may be seen in blood smears as part of the regenerative response but are not specific for regeneration?
anisocytosis increased numbers of nucleated RBCs basophilic stippling (aggregates of ribosomes and polyribosomes, especially seen in ruminants but can also be seen in dogs and cats) increased numbers of RBC containing Howell-Jolly bodies (remnants of the nucleus)
How does MCV change in a regenerative response to anemia?
within reference range early (takes 3-4 days for bone marrow to respond), then highest in hemolytic anemia (spherocytes from phagocytosis by macrophages and polychromatophils from regeneration) ***may be low with chronic blood loss
What does the MCHC look like in a regenerative anemia?
within reference range early low with a high percentage of reticulocytes, especially "stress reticulocytes"=released early from BM
Clinical signs of hemolytic anemia
depends on severity and speed of onset icterus may be present if rapid RBC destruction red plasma hemoglobinuria (if intravascular hemolysis present)
Laboratory findings of hemolytic anemia
reticulocyte counts higher than external hemorrhage plasma protein concentration normal or increased leukocytosis with neutrophilia and monocytosis bilirubinemia, hemoglobinemia, +/-hemoglobinuria abnormal erythrocyte morphology (ie. heinz bodies, poikilocytes, spherocytes, parasites)
Extravascular hemolysis often occurs in which organs?
spleen, liver, bone marrow
Which is acute or chronic - extravascular hemolysis or intravascular hemolysis?
Extravascular - can be either
intravascular - often rapid - per acute or acute
DIC occurs as a result of ________ (extravascular/intravascular) hemolysis.
both can cause DIC
Which has a worse prognosis intravascular or extravascular hemolysis?
intravascular - abnormal location for RBC destruction, usually rapid, not an isolated environment = fragments are a risk for DIC and anaphylactic shock
What is the pathological mechanism that causes hemoglobinuria?
lysed RBCs free Hgb into bloodstream - transport protein binds and it is taken to liver for metabolism and recycling. transport capacity is overwhelmed if destruction is rapid and/or severe enough - left over circulating Hgb is excreted in the urine
Where does bilirubin back up to first (if RBC destruction too rapid/severe to be excreted via normal mechanisms)?
backs up to urine and feces first = bilirubinuria then backs up in plasma = bilirubinemia then backs up to mucocutaneous tissues = icterus