Lecture 6 - Erythrocytosis "polycythemia" Flashcards
__ is an increased PCV, RBC ct, Hgb
erythrocytosis (polycythemia is a misnomer, this normally refers to neoplastic proliferation of RBC)
3 types of erythrocytosis
- relative
- transient
- absolute
What is the most common erythrocytosis caused by dehydration
relative erythrocytosis
what erythrocytosis is common in horses and is normally due to splenic contraction
transient erythrocytosis
__ normally have higher PCV’s (above reference interval) can be misinterpreted for erythrocytosis
sighthounnds (greyhouns)
__ causes relative erythrocytosis due to decreased plasma volume producing an increase in number of circulating RBCs
hemoconcentration
hemoconcentration (relative erythrocytosis) caused by
- dehydration (water loss - diarrhea, vomit, sweat, fever, decreased drinking)
- fluid shifts out of blood (edema, colic)
if both PCV and TP are high after exercise and there is evidence of __ during PE what do you suspect
dehydration, dehydration (must have observed dehydration too)
__ erythrocytosis is the redistribution of RBC in vascular sapce due to excitement, fear, exercise, pain, epinephrine, etc.
redistribution
redistribution erythrocytosis is caused by transient __ in response to epinephrine
splenic contraction (can mask an anemia!)
If have a post exercise increase in PCV but TP remains THE SAME
due to splenic contraction/redistribution
___ erythrocytosis is increased production of RBC with marrow erythroid hyperplasia
absolute
absolute erythrocytosis causes exercise intolerance, brick red mm, very high PCV (80%) with normal TP. Why?
blood is so thick it can’t deliver O2; sludges in capillaries and is prone to clots in small BV
what determines if absolute erythrocytosis is primary or secondary
erythropoietin
__ erythrocytosis is outside the control of EPO (normal or decreased EPO), it is characterized by uncontrolled RBC production due to myeloproliferative dz (cancer) and is uncommon
Primary absolute
primary absolute erythrocytosis is also known as
primary polycythemia, polychythemia ruba vera, or polycythemia vera
With primary absolute erythrocytosis or primary polycythemia there is __ EPO in circulation
normal (or decreased)
If primary polycythemia is suspected what should you check to rule out/ddx
PaO2, if there is normal blood O2 concentration then it is not “polycythemia” caused by hypoxemia
Is a p with primary polycythemia hypoxemic?
no, normal PaO2
what is the most uncommon erythrocytosis
absolute
increased __ production with secondary absolute erythrocytosis (can be hypoxemic or non-hypoxemic)
erythropoietin
increased __ production with primary absolute erythrocytosis
RBC
__ secondary erythrocytosis has a low PaO2 which stimulates normal EPO release. This can be seen in high altitudes and chronic cardio/pulmonary dz (things that effect O2 carrying capacity)
Hypoxemic (more common)
__ secondary erythrocytosis has a normal PaO2 but inappropriate EPO release due to poor renal flow (kidney things body is hypoxic when it’s not) or paraneoplastic syndrome
non-hypoxemic (uncommon)
__ (in this case) is due to tumor secreting EPO causing non-hypoxemic secondary erythrocytosis
paraneoplastic syndrome
A calf has signs or hypoxia and right sided CHF, there is an increased PCV and normal TP and no dehydration seen on PE. What are you thinking?
- Polycythemia (high PCV).
- Normal TP and PE, rules out relative (calf is not dehydrated)
- Bovides DO NOT have a contractile spleen, rules out transient
- Must be absolute, know it is secondary bc the PaO2 is low (if primary PaO2 would be normal).
- Now is it secondary due to hypoxemia or non-hypoxemia? Hypoxemia (has low PaO2, non-hypoxemia would have normal PaO2)
- ANSWER: Secondary absolute erythrocytosis due to hypoxemia
