Overview

• Polycythaemia ⇒ increase in haemoglobin concentration
  • Relative Polycythaemia ⇒ normal red cell mass but low plasma volume
    • Relative Causes → dehydration, stress
  • Absolute (True) Polycythaemia ⇒ increased red cell mass
• Polycythaemia Vera (Primary) → chronic myeloproliferative neoplasm, characterised by an erythropoietin-independent, irreversible increase in erythrocyte, granulocyte, and platelet counts
  • Risk Factor for Polycythaemia Vera ⇒ Budd-Chiari Syndrome
  • In 5-15% of cases, polycythaemia vera leads to acute myeloid leukaemia or myelofibrosis.
• Secondary Polycythaemia (driven by excess EPO)
  • Appropriate increase in EPO ⇒ due to chronic hypoxia (eg. chronic lung disease like COPD, living at high altitude)
  • Inappropriate increase in EPO ⇒ hepatocellular carcinoma, renal carcinoma, EPO abuse by athletes
• Elevated blood cell mass results in hyperviscosity, which is associated with slow blood flow and an increased risk of thrombosis
• Generally a disease of middle and older age

Making Diagnosis

Clinical Features:

• Constitutional Symptoms → weight loss, fatigue, sweating
• Hyperviscosity Syndrome → triad of mucosal bleeding, neurological symptoms (dizziness, headache) and visual changes
• Facial Redness
• Tenderness or painful burning and redness of fingers, palms, heels or toes
• Pruritus → worsens when skin comes in contact with warm water
  • May have scratch marks from itching
• Splenomegaly

Investigations:

• Haemoglobin → elevated and Haematocrit → elevated