apparent polycythaemia

Last edited 01/2020

Apparent polycythaemia (apparent erythrocytosis) describes an normal or minimally raised red cell volume with a reduced plasma volume. Causes include:

  • transient apparent polycythaemia:
    • dehydration
    • diuretic therapy
  • chronic apparent polycythaemia:
    • spurious polycythaemia
    • stress erythrocytosis - Gaisbock's syndrome

Management of apparent erythrocytosis patients include

  • spontaneous improvement is the rule
  • targeting in reduction or elimination of precipitating factors: smoking, obesity, hypertension and high alcohol consumption (1)
  • if no such factors are identified, venesection should be considered in the following patients
    • a recent history of thrombosis, or with additional risk factors for thrombosis
    • when the PCV is chronically greater than 0.54 (1).

Notes:

  • true increased red cell mass (i.e. not apparent erythrocytosis) can be assumed when the haematocrit is over 60% in males and 56% in females (2)
  • haematocrit returns to within the normal range in up to 30% of patients with untreated apparent erythrocytosis if serial measurements are undertaken (3)
  • those with a raised Hct but an Red Cell Mass studies within the normal range have an apparent erythrocytosis (4)
    • a relative erythrocytosis, found in states of dehydration, can be confirmed when the RCM is within the normal range and plasma volume is below normal
    • patients with a relative or apparent erythrocytosis require no further investigation

Reference:

Related pages:

polycythaemia