Patients with anaemia may be asymptomatic. A slowly falling level of Hb allows for haemodynamic compensation and enhancement of the oxygen-carrying capacity of the blood. A rise in 2,3-BPG causes a shift of the oxygen dissociation curve to the right, so that oxygen is more readily given up to the tissues. Where blood loss is rapid, more severe symptoms will occur, particularly in elderly people.

Symptoms (all non-specific)

• Fatigue
• Headaches
• Faintness

(The above three symptoms are all very common in the general population.)

• Breathlessness
• Angina
• Intermittent claudication
• Palpitations.

Signs

• Pallor
• Tachycardia
• Systolic flow murmur
• Cardiac failure
• Rarely papilloedema and retinal haemorrhages after an acute bleed (can be accompanied by blindness).

Specific signs of the different types of anaemia will be discussed in the appropriate sections. Examples include:

• koilonychia – spoon-shaped nails seen in iron deficiency anaemia
• jaundice – found in haemolytic anaemia
• bone deformities – found in thalassaemia major
• leg ulcers – occur in association with sickle cell disease.

It must be emphasized that anaemia is not a diagnosis, and a cause must be found.