POLYCYTHAEMIA

Relative

• dehydration

• Gaisböck’s syndrome (stress)

Primary

• polycythaemia rubra vera (splenomegaly, raised platelets)

Secondary

• hypoxia

• smoking

• chronic obstructive pulmonary disease
• altitude
• abnormal haemoglobins
• sleep apnoea and extreme obesity (Pickwickian $)

• cyanotic heart disease

Excess erythropoietin

• cerebellar haemangioma

• hepatoma
• phaeochromocytoma
• hypernephroma
• polycystic/transplant kidneys; RCC
• uterine leiomyoma/fibroma

Also Relative polycythemia secondary to plasma volume loss (eg, dehydration, excessive diureses)

RBC mass, SaOw, and EPO level are all normal.

Primary polycythemia/ Polycythemia vera

• common in age 60 - 75
• overproduction of all three hematopoietic cell lines with predominant elevation in red cell counts
• Due to random acquired mutation in the JAK2 protein which regulates marrow production
• The V617F mutation is found in approximately 96% of people with primary polycythemia, 60% of essential thrombocythemia (ET) and primary myelofibrosis (PMF). Around 3% of affected individuals have a mutation in the exon 12 region of the JAK2 gene.
• red cells grow wildly despite a Low erythropoietin level