haematocrit ( HCT , ( packed cell volume , PCV ))

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  • males 40-52%
  • females 36-48%

A raised haematocrit reflects haemoconcentration. This may be relative due to reduced plasma volume, or absolute (increased red blood cell mass):

  • reduced plasma volume - often result of dehydration e.g. alcohol, diuretic therapy. Also may occur in acute pancreatitis (there may be a decreased haematocrit in severe haemorrhagic pancreatitis), Addison's disease (because of water loss)
  • increased red cell mass - primary (polycythaemia rubra vera) or secondary e.g. chronic lung disease, smoking, altitude, tumours (hepatoma, fibroids, hypernephroma)


  • true increased red cell mass can be assumed when the haematocrit is over 60% in males and 56% in females (1)
  • comparing individuals with a haematocrit which is in the upper normal range, or slightly elevated to those with a haemocrit values in the middle or lower part of the normal range
    • individuals with a haematocrit may be associated with an increase in thrombotic events and cardiovascular mortality (2)

Note that normal ranges vary with different commercial kits.


  1. Pearson, T.C. Evaluation of diagnostic criteria in polycythemia vera. Seminars in Hematology 2001;38(1 Suppl 2): 21-24.
  2. Lowe, G.D. Rheological influences on thrombosis. Baillieres Best Practice & Research. Clinical Haematology 1999;12(3): 435-449.