Erythrocytosis

Question 1

What is erythrocytosis?

Answer 1

increased RBC and PCV/Hct

Question 2

What is the difference between absolute and relative erythrocytosis?

Answer 2

ABSOLUTE - true increase in red cell mass (increased RBCs in circulation)

RELATIVE - RBC mass doesn’t increase in volume, but PCV and RBC count (hemoconcentration due to decreased fluid volume)

Question 3

What’s the difference between primary and secondary absolute erythrocytosis?

Answer 3

PRIMARY - in the abscence of increased EPO (polycythemia vera)

SECONDARY - increased EPO activity

Question 4

What care causes of appropriate and inappropriate secondary absolute erythrocytosis?

Answer 4

APPROPRIATE = decreased tissue oxygenation
- pulmonary disease
- R to L CV shunts
- heart failure
- high altitude
- hyperthyroidism

INAPPROPRIATE = normal tissue oxygenation
- hyperadrenocorticism
- renal masses that produce EPO
- neoplasm

Question 5

What is the most common cause of relative erythrocytosis? What other bloodwork values are typically increased?

Answer 5

hemoconcentration caused by dehydration or splenic concentration

TS/TP

Question 6

When are clinical signs seen with erythrocytosis? What are 7 signs?

Answer 6

> 70-80% PCV

1. increased blood viscosity
2. decreased perfusion to the CNS = acute neurologic abnormalities (depressed)
3. spastic tetraparesis, seizures, ataxia, paraparesis, collapse
4. behavioral changes
5. PU/PD
6. paroxysmal sneezing (polycythemia vera)

Question 7

What is most commonly seen on physical exams in patients with erythrocytosis?

Answer 7

• bright red MM
• erythema
• splenomegaly
• renal masses

Question 8

How can dehydration be ruled out as a cause of erythrocytosis?

Answer 8

• high TP
• (lack of) signs of dehydration of examination
• response of PCV to flud therapy

Question 9

What are the 3 most common secondary causes of erythrocytosis? How can it be diagnosed?

Answer 9

1. respiratory disease - hypoxia (appropriate secondary)
2. cardiac disease - hypoxia (appropriate secondary)
3. renal masses - EPO production (inappropriate secondary)

Question 10

How is primary erythrocytosis diagnosed?

Answer 10

(polycythemia vera)

• bone marrow biopsy to look for neoplasia
• EPO concentrations usually low or normal

Question 11

What 2 treatments are recommended for primary erythrocytosis?

Answer 11

1. therapeutic phlebotomy - removing RBCs and replaces with crystalloids to decrease blood viscosity
2. hydroxyurea - chemotherapy stops bone marrow from producing RBCs