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Greek. anaimia : from an - without, haima - blood

Low concentration of haemoglobin in the blood. Usually <10g/dl, but there are significant gender differences and it may be more useful to consider the stage of life and relevant physiology, e.g. pregnancy (see Full_blood_count:Interpretation).




Some Causes of Anaemia

Normocytic anaemia

Microcytic anaemia

(MCV <78 fl)

Macrocytic anaemia

(MCV>98 fl)

Post-operative Anaemia

Bleeding is unavoidable in certain procedures. Often it is enough to replace lost volume with crystalloid or colloid as fit with good cardiorespiratory reserve tolerate haemodilution well if euvolaemia is maintained.

The need for replacement with blood depends on the drop in haemoglobin and on the patient (with lower thresholds for transfusion in patients with ischaemic heart disease). The current trend is towards a more conservative approach aiming for a haemoglobin of 8-9g/dL. There are several reasons for this:

  • Studies which show no advantage to a more liberal policy which employ a higher final haemoglobin level.
  • Optimum haemodynamics may be better at lower haematocrits.
  • There is a small, but recognised risks of blood transfusion.
  • The lessons learned from blood borne viruses such as HIV and the hepatitis viruses mean that there remains an unquantifiable risk of yet unrecognised blood borne infections (e.g. ?nvCJD).

The use of post-operative iron supplementation is common practice, but as iron stores are often not depleted, its use does not have a sound physiological basis as iron is rarely the limiting factor in post-operative erythropoeisis.[1] Most of the trials have been in orthopaedic surgery.[2][3]

Other alternatives:


Severe anaemia may require hospital admission and transfusion, but transfusion is not without problems, as a sudden load on the circulation, combined with stored red cells not immediately delivering oxygen well may overload the heart.

Deciding on the cause is urgent, and excluding persistent causes important.