Lecture 4 Flashcards
What species are reticulocytes NOT released in response to anemia
Horses
What are 2 ways to correct the reticulocyte percent
Calculate Absolute Reticulocyte count
Calculate corrected reticulocyte percent
How do you calculate the absolute reticulocyte count?
RBC count X uncorrected reticulocyte count as a decimal = absolute reticulocytes
How do you calculate the corrected reticulocyte percent?
(patient’s PCV/ mean norm. PCV for species) X uncorrected reticulocyte as a % = corrected reticulocyte percent
What are two causes of regenerative anemia?
Hemorrhage
Hemolysis
What are the 2 types of hemorrhage
External and internal
What are the features of external hemorrhage
RBC’s are lost
Iron is lost
Blood proteins are lost
If chronic, iron loss can be so severe RBC production stops
IF iron deficiency, non-regenerative anemia may develop
What are some causes of external hemorrhage
Trauma
Bleeding GI or UG lesions
Blood sucking parasites
some hemostatic disorders
What are the features of internal hemorrhage
RBC’s are NOT lost
Iron is CONSERVED and available to make new RBC’s
Blood proteins are NOT LOST
autotransfusion may occur from a hemoabdomen or hemothorax
What are some causes of internal hemorrhage
Trauma
Bleeding tumors of intra-abdominal or thoracic organs
some hemostatic disorders
What happens initially with acute hemorrhage?
Blood cells and blood fluid are both lost in equal amount
total blood volume is decreased
At first, PCV remains the same because relative proportion of blood cells to blood fluid is unchanged
What are the initial protective responses that occur to preserve oxygen delivery with acute hemorrhage?
Heart rate and blood pressure increase Splenic contraction (releases stored RBC's) Body tissue fluids (interstitial fluid) slowly moves from tissues to blood vessels so remaining RBC's and TP are diluted
What are 2 classic findings after hemorrhage?
anemia and panhypoproteinemia
What are the laboratory findings with acute hemorrhage
Initial findings may not reveal anything
Fluid shift starts 3 hrs post hemorrhage and continues for 2-3 days post hemorrhage
Decreased PCV and total protein will show up ~ 12-24 hours post hemorrhage
What are some factors that may influence the lab findings with acute hemorrhage?
Splenic contraction - increases PCV acutely
Autotransfusion - increases PCV slowly
Fluid therapy prior to transfusion can dilute the PCV and TP even more along with the interstitial fluid shift
How long does it take the regenerative response to anemia to appear in the blood
3-4 days
1 week in old or debilitated animals
When does the peak regenerative response occur
1 week post hemorrhage
is the regenerative response more or less dramatic in ruminants
less but more basophilic stippling
Because equids do not release reticulocytes what do we need to do evaluate the regenerative response?
Check PCV every few days
Check bone marrow
What are some things to remember when assessing regenerative anemia in horses?
Splenic contraction happens readily
Do not release reticulocytes or exhibit polychromasia
Freshly matured RBC’s are larger than older RBC’s so:
- MCV, RDW, and anisocytosis will be increased
What is the lifespan of RBC’s in circulation?
~100 days
How are old RBC’s removed
As RBC’s age, damage to the membrane occurs and the receptors on the membrane begin to trimerize which the macrophage recognizes and then engulfs the RBC
What happens when RBC’s are broken down
Hemoglobin –> Heme + globin
Heme –> iron + unconjugated bilirubin
Useful nutrients from dead RBC’s are recycled ie. iron, amino acids
liver metabolizes bilirubin which is excreted in urine and feces
What are the two classifications of hemolytic anemia
congenital and acquired
Which classification of hemolytic anemia is more common
Acquired
What is hemolysis?
abnormally increased rate of erythrocyte destruction
erythrocyte lifespan is reduced causing anemia
The severity of the hemolytic anemia and clinical signs depend on:
how fast the RBC’s are destroyed
clinical signs also depend on the predominant site with in the body the RBC’s are being destroyed
Where is the predominate site of Extravascular hemolytic anemia
macrophages in the spleen
Where does intravascular hemolytic anemia occur
blood stream
What are the features of Extravascular hemolysis
Abnormal RBC death occurs in a normal location (spleen)
Can be acute or chronic
Macrophages remove RBC’s as they pass through the spleen
DIC is possible
What are the features of intravascular hemolysis?
Abnormal RBC death occurs in an abnormal location (blood stream)
Often acute (very rapid)
Circulating fragments or damaged RBC’s increase risk of DIC and anaphylactic shock
Lysed RBC’s from intravascular hemolysis release what into the blood stream?
Free hemoglobin
What does the circulating free hemoglobin cause?
Hemoglobinemia (plasma is pink or red)
what protein mops up free hemoglobin and transports it to the liver
Haptoglobin
What occurs when haptoglobin transport capacity is overwhelmed
Not all of the hemoglobin is captured by the haptoglobin and is excreted in the Urine HEMOGLOBINURIA
How is bilirubin excretion affected if RBC destruction is severely rapid.
bilirubin excretion is first backed up in the urine and feces causing it to turn an orange color (bilirubinuria)
Then it backs up in the plasma causing (bilirubinemia)
Then it can eventually cause icteric mucocutaneous membranes
What will you see with Extravascular hemolysis
Bilirubinuria
Bilirubinemia
Mucocutaneous icterus
What will you see in Intravascular hemolysis that you won’t see in extravascular hemolysis?
Hemoglobinemia
Hemoglobinuria
What are possible clinical findings with hemolytic anemia?
Anemia (low PCV and RBC)
TP - reflects hydration status
RBC morphology may reflect the underlying cause of hemolysis
Clinical signs of anemia
may have fever, organomegaly of spleen, liver, lymph nodes
discolored urine, feces, plasma, or membranes
Abnormal RBC shape
Poikilcytosis
Give the different names of abnormal RBC shapes
Acanthocytes Schistocytes Keratocytes Spherocytes RBC ghosts Eccentrocytes and pyknocytes
What are 2 abnormal RBC inclusions?
Heinz bodies
Infectious RBC parasites
What abnormal RBC shape occurs usually as an artifact
Echinocyte
What can cause echinocytes
IF RBC membrane sits in tube too long it loses ATP causing artifacts
can also be caused by inappropriate ratio of anti-coagulant
What RBC shape occurs as a result of fragmentation or liver disease?
Acanthocytes
What 3 things can cause fragmentation
Mechanical injury
Endothelial injury
Thermal injury
What RBC shape is seen with DIC and fragmentation
Schistocytes
What RBC shape is a red flag ofr Immune mediated hemolytic anemia
Spherocytes
What do spherocytes look like?
smaller perfectly round RBC’s with no central pallor
What RBC shape occurs as a result of Intravascular hemolysis
RBC ghosts
How are RBC ghosts formed
macrophage undergoes complement mediated lysis of the cells / macrophage basically punches holes in the cell so hemoglobin leaks out into the blood and urine causing hemoglobinemia and hemoglobinuria
What blood shape is formed from oxidative damage
Eccentrocytes
What are the 3 targets for oxidative damage of RBC’s
Lipid membrane (becomes oxidized and pushes hemoglobin away)
Heme
Globin molecule
What forms when the globin molecule undergoes oxidation and sticks to the cell membrane
Heinz bodies
