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Perth Haematology :: Dr Steven Ward

Polycythaemia Rubra Vera (PRV)



Polycythaemia = too much red blood (increased red blood cell mass)


This may be:

bulletPrimary : PRV - due to increased marrow red cell production
bulletSecondary: ie an appropriate or stimulated
bulletincreased red cell mass due to hypoxia (lack of oxygen) - in lung or heart disease
bulletdue to liver, brain or kidney disorders
bulletRelative: due to reduced plasma volume and normal red cell mass
bulletApparent: high Haematocrit but normal red cell mass


 Polycythaemia leads to:


Increased Hb, Red Cell Count (RCC) and Haematocrit (Hct) [Hct is also known as Packed Cell Volume (PCV)]


Increased blood viscosity


Features of the causative disorder (lung or heart usually)


Primary PRV also causes a rise in the white cells and platelets, enlarged spleen and high blood uric acid levels (and potentially gout)


Untreated polycythaemia can lead to thrombosis - stroke or myocardial infarction; hypertension; bleeding.



The best way to diagnose polycythaemia is by a Red Cell Mass (RCM) study. This involves the drawing of a measured amount of patient blood, labelling that blood with a known amount of a mild radioactive tracer which bins the red cells, and a second tracer to bind a plasma component (usually albumin). The patient blood with tracers is then reinjected to the patient and allowed to mix and circulate with the rest of the blood. After a time a second blood sample is taken and the radioactivity in this sample is measured. The red cell mass, blood volume and plasma volume can then be calculated.


Normal values:

                                MALE    FEMALE

Red Cell Mass        25-35      22-30        mL/kg body wt

Plasma Volume      28-38      31-38        mL/kg

Blood Volume         52-70      54-64        mL/kg


Mean Predicated RCM = 0.47 x 0.91 x BV for males       Values > 25% above this = polycythaemia

                                            0.43 x 0.91 x BV for females    Values > 35% above this = polycythaemia


    OR      Males: (1486 x SA)-825 mL

                Females: (1.06 x Age) + (822 x SA) mL                SA = Surface Area


Additional Tests to find the Cause of Absolute polycythaemia


Arterial Blood Gases - to measure oxygen and CO2 levels in the blood.


Chest x-ray - to look for lung / heart disease


Ultrasound of abdomen - to look for liver or kidney causes


Hb electrophoresis - to look for a high-affinity Hb variant (inherited disorder of Hb with high-affinity for oxygen, so doesn't give oxygen up to tissues easily)


Bone marrow studies - to exclude other primary MPD


Marrow cytogenetics and molecular markers - BCR-ABL and JAK2


Diagnostic Criteria for PRV [BCSH]

    Major:    A1: Increased RCM  >25% above predicted mean or HCt  M > 0.6  F >0.56

                    A2: No cuase for 2y erythrocytosis

                    A3: Palpable splenomegaly

                    A4: Clonality marker

    Minor:    B1: Thrombocytosis (>400)

                    B2: Neutrophilia (>10; or >12.5 in smokers)

                    B3: Splenomegaly on USS

                    B4: Reduced serum EPO level


    A1 + A2 + (A3 or A4) = PRV

    A1 + A2 + any  2 B = PRV


Revised WHO Diagnostic Criteria for PRV

Diagnosis requires both major criteria and 1 minor criterion or 1st major plus 2 minor criteria.


Major Criteria:

1.      Hb > 185 g/L in men, 165 g/L in women, or other evidence of raised red cell volume [Hb or Hct > 99th percentile; Hb >170 M, 150 F  with documented and sustained increase of >20g/L from individualís baseline; RCM > 25% above mean normal predicated value]

2.      JAK2617V>F or other functionally similar mutations eg JAK2 exon 12 mutation


Minor Criteria:

1.      BM biopsy showing hypercellularity for age with panmyelosis with prominent erythroid, granulocytic and megakaryocytic proliferation

2.      Serum EPO below the reference range

3.      Endogenous erythroid colony formation in vitro





The aim is to reduce the Hct to <0.45 to prevent hyperviscosity (and subsequent hypertension, artherosclerosis, heart disease) and prevent thrombosis and bleeding.


Aspirin 75mg/day has been shown to be effective at reducing thrombosis


Venesection (blood letting): safest therapy - maintain Hct <0.45


Hydroxyurea : reduces HCt, thrombois and bleeding. Recent studies show no increase in leukaemia or fibrosis risk above that for the disease itself.


Other drugs: interferon, 32P (radioactive phosphorus) are occasionally used


Itch can be  problem: often relieved by treatment of the PRV itself; other possible treatments are: cimetidine, PUVA, interferon, SSRIs.


Risk of Acute Leukaemia: 1.5%

Risk of Myrlofibrosis: 5-15%