Primary polycythemia and Erythrocytosis Flashcards
Define erythrocytosis.
increased number of RBC, hemoglobin concentration, and HCT
- due to increased RBC cell mass, or decreased plasma volume
Define relative polycythemia.
When there is loss of plasma volume, leading to a relative increase in RBC mass
(vomiting, diarrhea)
Define primary polycythemia.
The negative feedback loop is still intact, ex. JAK2 mutation in people
Define secondary polycythemia.
- could still be physiologically appropriate - as a response to hypoxemia
- or physiologically inappropriate - due to increase in erythropoietin without concurrent hypoxemia - paraneoplastic
What role does thyroid hormone play in erythropoiesis?
Thyroid hormone stimulates proliferation of erythyroid progenitor cells and also enhances HIF-1
What role does glucocorticoids play in erythropoiesis?
It synergizes with HIF to stimulate burst forming units
What are some clinical signs of polycythemia?
- for relative polycythemia = dehydration, fluid loss
- for secondary inappropriate polycythemia = could be signs of underlying disease (cardiovascular, respiratory, renal or neoplasia)
How is polycythemia diagnosed?
most important to ddx between relative, secondary appropriate, and secondary inappropriate
- relative: signs of dehydration, fluid loss - Tx with IV fluids
- hypoxemia = arterial PO2 < 92%
- primary polycythemia = normal PO2 saturation, no underlying conditions that’s associated with secondary polycythemia
- primary polycythemia has been associated with cardiac hypertrophy and transient glomerulopathy?
How is polycythemia treated?
- aim at controlling the clinical signs
- phlebotomy: need to replace volume loss with IV fluids (15-20ml/kg)
- myelosuppressive therapy: hydroxyurea, chlorambucil (has more side effects)
Complications:
- over zealous phlebotomy: can lead to iron deficiency, hypoproteinemia, and peripheral edema
- AE associated with myelosuppressive therapy
- thrombosis: documented complications in people, not in vet med
