Anaemia
From Ganfyd
ΕΤΥΜΟΛΟΓΙΑ
Greek. anaimia : from an - without, haima - bloodLow 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).
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Symptoms
- Shortness of breath on exertion
- Tiredness
- Headache
- Angina
Classification
- Point in biological pathway at which production of haemoglobin is deranged
- Size of erythrocyte
- Divide into macrocytic / normocytic / microcytic on basis of mean cell volume (MCV)
- Hereditary vs Acquired
Some Causes of Anaemia
Normocytic anaemia
- Most haemolytic anaemias
- Anaemia of chronic disease (sometimes)
- Haemorrhage
- Renal disease
- Bone Marrow Failure
- Mixed causes
Microcytic anaemia
(MCV <78 fl)
- Iron deficiency
- Bleeding (so make sure to exclude GI malignancy)
- Malabsorption
- Dietary deficiency
- Thalassaemia
- Other haemoglobin defects
- Anaemia of chronic disease (sometimes)
- Congenital sideroblastic anaemia
- Lead poisoning
Macrocytic anaemia
(MCV>98 fl)
- (megaloblastic anaemia)
- B12 / folate deficiency
- non-megaloblastic
- Acquired sideroblastic anaemia
- Alcohol
- Liver disease
- Hypothyroidism
- Myelodysplasia
- Aplastic anaemia
- Cytotoxic drugs
- Pregnancy
- Smoking
- Reticulocytosis
- Myeloma
- neonatal (first few days)
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:
- Cell salvage
- Autologous transfusion
- Erythropoeitin
Treatment
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.
References
- ↑ Biesma DH, Van de Wiel A, Beguin Y, Kraaijenhagen RJ, Marx JJ. Post-operative erythropoiesis is limited by the inflammatory effect of surgery on iron metabolism. European journal of clinical investigation 1995;25:383-9.
- ↑ Sutton PM, Cresswell T, Livesey JP, Speed K, Bagga T. Treatment of anaemia after joint replacement. A double-blind, randomised, controlled trial of ferrous sulphate versus placebo. The Journal of bone and joint surgery. British volume 2004;86:31-3.
- ↑ Mundy GM, Birtwistle SJ, Power RA. The effect of iron supplementation on the level of haemoglobin after lower limb arthroplasty. The Journal of bone and joint surgery. British volume 2005;87:213-7.
