What is anaemia?
Lower than normal haemoglobin for the age and sex of the patient
Classifications of anaemia?
1. Basic mechanism
- ineffective production
- impaired red cell survival
- small and pale
Causes of impaired production?
Deficiency of substances essential for red cell production
- iron, vitamin B12, folate
Genetic defect in red cell production
Failure of bone marrow
- Infiltration eg. leukaemia, irratiation or drug damage
Reduced red cell survival?
- usually acute trauma or surgery
- shortened survial of the red cell
- RBC being broken down = billirubin in excess = jaundice
Morphological approach to anaemia?
Uses MCV, average Hb concentration and blood film comment
Microcytic hypochromic anaemia (MCV < 76)
Normochromic normocytic anaemia (MCV 76-96)
Macrpcytic anaemia (MCV >96)
(NB: Packed cell volume (PCV) or Haematocrit = % of red cell volume to total blood volume and basically mirrors the Hb)
Differential for Microcytic hypochromic anaemia?
Iron deficiency - most common cause of anaemia
Chronic illness - iron block
genetic - thalassaemia (globin chains are insufficient)
Diagnosis of Iron deficiency?
- Measure serum iron, iron binding capacity (transferrin normally 30%) and iron saturation
- Measure Serum Ferritin
- Rarely examin iron stores in bone marrow
classical patterns of iron deficiency vs anaemia of chronic disorder?
Iron deficiency shows a low serum ferritin but as iron is low the body produces iron transport protein so the trasnferrin % drops.
In anaemia of chronic disorder the serum ferritin is actually normal or elevated whist the serum iron is low along with a low iron transport protein.
Causes of Iron Deficiency?
- eg. vegetarian
Malabsorption (normally only absorb 1-2mg from 15 per day)
- proximal small bowel
- eg. pregnancy and breastfeeding
Chronic blood loss (Most clinically important)
- GI or GU tract