Cross Species - Red Blood Cell Parameters Flashcards
what are the 3 cell types evaluated on a CBC? what does it provide information on?
erythrocytes, leukocytes, & platelets - info on production, structure, & function
what is hematopoiesis?
blood cell production that occurs primarily in the bone marrow
what does the bone marrow contain which produce cells? what are the precursors?
progenitor/stem cells & mesenchymal stromal cells that secrete cytokines to control stem cell differentiation - myeloid precursors for WBC, erythroid precursors for RBC, & megakaryocytes for platelets
why is it important that hematopoietic stem cells are multipotent?
they can self-renew & can differentiate into all cell types
what causes red blood cell production?
erythropoietin is released from the kidneys in response to tissue hypoxia
what is seen on a CBC in an animal with a lack of erythropoietin?
non-regenerative anemia
what is the exception to circulating nucleated red blood cells?
snakes, fish, amphibians, & birds all have circulating nucleated red blood cells
how do you differentiate between immature & mature RBC?
immature red blood cells, rubricytes, have a nucleus while mature RBC don’t
what is the last red blood cell stage prior to a mature RBC? what do they look like?
reticulocytes - no nucleus, but they contain RNA that can be seen with a special stain
what is the purpose of counting reticulocytes on a CBC?
to assess the bone marrow response to anemia
T/F: you can count reticulocytes from a horse CBC to assess their anemia
false - reticulocytes are not present in horses!!!
T/F: red blood cells are very susceptible to oxidative damage
TRUE
what are heinz bodies?
RBC containing oxidized precipitated hemoglobin
what are the big causes of oxidative damage to RBC?
toxins - acetaminophen in cats, red maple leaf toxicity in horses, & alium species in onions & disease - feline hepatic lipidosis, systemic inflammation, & neoplasia
what is the lifespan of RBC in cats?
2 months
what is the lifespan of RBC in dogs?
3 months
what is the lifespan of RBC in cows & horses?
about 5 months
how are RBC removed from circulation?
splenic macrophages remove them, iron is recycled & used again in bone marrow - poryphrin produced by heme breakdown is excreted via a bilirubin pathway
what does it mean if hemoglobinemia is seen in circulation?
indicates RBC rupture is occuring within the vasculature - intravascular hemolysis, clinically correlates with babesiosis
what does extravascular hemolysis cause?
bilirubinemia (pre-hepatic icterus) from increased production of bilirubin precursos (canine IMHA & equine infectious anemia)
T/F: hematocrit & PCV are not the same
TRUE
how is HCT calculated?
HCT = (MCV x RBC)/10
how is PCV measured?
directly measured from centrifuged microhematocrit tube & then interpreted in conjunction with total solids
how are total solids measured?
measurement of plasma protein using a refractometer
what is the buffy coat?
layer of WBC & platelets on top of the RBC
what does a spurious increase in HCT/PCV indicate?
insufficient centrifugation or cell swelling with storage for HCT
what are the main causes of a pathologic increase in HCT & PCV?
dehydration is most common, splenic contraction, epinephrine release in horses, & polycythemia
what is polycythemia?
primary myeloproliferative disease such as polycythemia vera or secondary polycythemia due to increased erythropoetin production (congenital heart disease causing left to right shunting)
what does a spurious decrease in HCT or PCV indicate?
in vitro hemolysis or underfilled EDTA tube causing sample dilution
what are the 3 mechanisms of true anemia?
RBC breakdown, RBC loss, & lack of production
what is an example of a disease causing break down of RBC resulting in anemia?
IMHA in dogs
what is an example of a disease causing blood loss of RBC resulting in anemia?
external - trauma, guttural pouch mycosis & internal/occult - gi losses, renal losses, & body cavity bleed
what is an example of a disease causing decreased production of RBC resulting in anemia?
neoplasia & toxin-mediated bone marrow suppression
what is an example of an iatrogenic cause of anemia?
over hydration
what parameters are related to hemoglobin on a CBC?
mean cell hemoglobin (MCH) & mean cell HGB concentration (MCHC)
hemoblobin can be estimated based off of HCT how?
1/3 of hematocrit
what are some causes of a spurious increases in hematocrit?
lipemia, heinz bodies, & high numbers of nRBC
how is MCH calculated?
HGB/RBC - detects the average amount of HGB in cells, but rarely used because it is affected by cell size, so the result is difficult to interpret
how is MCHC calculated? what does it represent?
(HGB/HCT) X 100 - average RBC hemoglobin concentration, calculation accounts for cell size because HCT = RBC X MCV
T/F: an increase in MCHC is ALWAYS spurious
TRUE
why are increases in MCHC always spurious? what are some examples of causes?
RBC cannot contain increased hemoglobin!!!! causes include lipemia, hemolysis, many rRBC, & agglutination
what are causes of decreased MCHC?
regenerative anemia & iron deficiency anemia - immature RBC contain less hemoglobin!!!
what are some spurious causes of increased MCV?
agglutination & excessive blood storage time
what does an increase in MCV mean?
macrocytosis is present
how is MCV calculated? what does it represent?
(PCV/RBC) X 10 - measure of RBC volume
what are some pathologic causes of an increased MCV?
regenerative anemia, RBC swelling due to membrane abnormalities, folate deficiency, B12 deficiency, & myelodysplasia (cats with FeLV)
what breed is associated with a physiologic cause of a decreased MCV?
akita
what is an example of a physiologic cause of a decreased MCV?
young animals - puppies & kittens less than 16 weeks old & calves & foals less than 2 months old
what is an example of a pathologic cause of a decreased MCV?
iron deficiency - chronic external blood loss (gi bleeding) or insufficient intake (piglets)
what is RDW?
measures the variation in RBC volume (anisocytosis)
what does an increase in RDW indicate?
more variation in RBC size/volume - seen with anemia due to larger immature RBC if regenerative or smaller/older RBC if non-regenerative
what special stain is required for a reticulocyte count?
methylene blue
how long does a regenerative anemia take to see on a CBC?
3-5 days
what does a higher count of reticulocytes indicate?
there is a regenerative anemia
T/F: it is difficult to assess if an anemia is regenerative or non-regenerative in a horse without a bone marrow aspirate
TRUE
when do you need to manually count WBC when considering nRBC?
if greater than 5/100 WBC - analyzers count the nRBC as WBC!!
when may you see an increase in nRBC?
regenerative anemia, bone marrow injury, dogs with heat stroke, lead poisoning, & splenic hemangiosarcoma
why do you need to do a microscopic slide for RBC?
analyzers won’t tell you anything on changes in RBC morphology
