Erythropoiesis

Question 1

What causes an overproduction in erythrocytes?

Answer 1

Myeloproliferative disorders
Or
Physiological reactions

Question 2

What are the 3 types of myeloproliferative neoplasms?

Answer 2

Essential thrombocythaemia
Polycythaemia Vera
Myelofibrosis

Question 3

What are the clinical features of meyloproliferative disorders?

Answer 3

• overproduction of one or several blood elements with dominance of a transformed clone
• hypercellular marrow / marrow fibrosis
• cytogenetic abnormalities
• thrombotic and/or haemorrhagic diatheses
• extramedullary haematopoiesis (liver/spleen)
• transformation to acute leukaemia

Sticky blood and thrombosis

Question 4

What is polycythaemia vera and what does it cause?

Answer 4

Too many red cells

Raised haematocrit or raised cell mass

Question 5

If you notice high haematocrit levels what might the causes be?

Answer 5

Polycythaemia (increase in circulation red cells)

Erythrocytosis (increase in the conc of RBCs)

Question 6

Explain what the difference between relative and absolute erythrocytosis is

Answer 6

Relative= normal red cell mass, lower plasma volume leading to more concentrated blood

Absolute= increased red cell mass

Question 7

What is the difference between primary and secondary erythrocytosis?

Answer 7

Primary- polycythaemia vera

Secondary- drive by erythropoietin EPO production
(Physiologically appropriate ie in response to hypoxia or physiologically inappropriate)

Question 8

What might be a reason physiologically appropriate EPO production causing secondary erythrocytosis?

Answer 8

Central hypoxia: 
Chronic lung disease
R to L shunt
Training at altitude
CO poisoning 

Renal Hypoxia:
Renal arty stenosis
Polycystic disease

Question 9

What might be a reason for pathological EPO production causing secondary erythrocytosis?

Answer 9

Hepatocellular carcinoma 
Renal cell cancer
Cerebellar haemangioblastoma 
Parathyroid tumours
Uterine leiomyomas
Phaeochromocytoma
Meningioma

Question 10

What might be another reason for EPO in the blood other than physiological and pathological reactions?

Answer 10

Doping

Question 11

What are the clinical features of polycythaemia vera?

Answer 11

Significant causes of arterial thrombosis
Venous thrombosis
Haemorrhage into skin or GI tract
Pruritis
Splenic discomfort, splenomegaly
Gout
Can become myelofibrosis or acute leukaemia

Question 12

What is the treatment for polycythaemia vera?

Answer 12

Venesection (taking units of blood)

Aspirin to thin the blood

Manage CVS risk factors

Use drugs to reduce the overproduction of cells should be considered if:
Poor tolerance of venesection
Symptomatic or progressive splenomegaly
Other evidence of disease progression eg weight loss, night sweats
Thrombocytosis