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