Anaemia

Anaemia

1. Definition

   • Blood Components
   • Reduction in haemoglobin concentration causing decrease in oxygen carrying capacity
   • It is not a diagnosis - is an abnormal clinical finding
   • RBCs
     • 8 um diameter, biconcave, flexible oval
     • 10^12 made in bone marrow everyday - erythropoiesis
       • 120 day lifespan - destroyed by macrophages in spleen
   • Haemaglobin
     • 640 million molecules per RBC
     • Tetrameric structure - 2 pairs of different polypeptide chains, 1 haem molecule
       • Globin (polypeptide chains)
         • Permits variability in oxygen affinity
         • Protects haem from oxidation
         • Makes the molecule soluble
     • HbF has higher affinity for oxygen, HbS has lower affinity (than normal)
     • 3 Main types
       • HbA - alpha2beta2
         • 96-98% in blood
       • HbA2 - alpha2delta2
         • 1.5-3.2% in blood
       • HbF - alpha2gamma2
         • 0.5-0.8% in blood
     • Contains 65% of body iron
       • 30% is ferritin and haemosiderin
         • Rest is myoglobin, haem enzymes (cytochromes), transferrin

2. Symptoms

   • May not be any - depends on speed of onset, severity and age
   • Tiredness/Lethargy
   • Shortness of breath
   • Palpitations
   • Headaches
   • In old people
     • Cardiac failure
     • Angina
     • Intermittent claudication - muscle pain
     • Confusion
   • Signs
     • General
       • Pallor of mucous membranes - if Hb <9-10 g/dL
       • Hyperdynamic circulation
         • Tachycardia
         • Bouncing pulse
         • Cardiomegaly
         • Systolic flow murmur
       • Signs of heart failure
     • Specific
       • Koilonychia (spoon nails) - iron deficiency
       • Jaundice - Haemolytic/megaloblastic anaemia
       • Leg ulcers - sickle cell disease
       • Bone deformities - thalassaemia major
       • Associated infetions/bruising - bone marrow failure

3. Classification

   • Microcytic - MCV <80 fl
     • Iron deficiency
     • Thalassaemia trait
     • Anaemia of chronic disease
   • Normocytic - 80-95 fl
     • After acute blood loss
     • Haemolytic anaemias
     • Bone marrow failure
   • Macrocytic - >95 fl
     • Megaloblastic - vitamin B12/folate deficiency
     • Non-megaloblastic - alcohol, liver disease, myelodysplasia

4. Investigations

   • In all cases
     • Full blood count - red cell indices, white cell/platelet count
     • Blood film
   • Depending on Blood Count/Film
     • Reticulocyte count
     • Hb electrophoresis
     • Bone marrow biopsy
       • Taken from pelvis
         • Short needle for aspirate
         • Long needle for core
     • Bilirubin/LDH/haptoglobin test
     • Haematinics
       • Ferritin, iron studies, vitamin B12, folate

5. Microcytic Anaemia

   • Most common - 500 million people affected
   • Caused by limited ability to absorb iron
     • Excess loss due to bleeding common
     • Iron requirement goes up in pregnancy, adolescence and menstruation
   • Average daily intake of iron - 10-15 mg (best source is meat)
   • Clinical features
     • General signs/symptoms
     • Painless glossitis (tongue inflammation)
     • Angular stomatitis (corners of mouth)
     • Koilonychia
     • Children
       • Irritability
       • Poor cognitive function
       • Decline in psychomotor development
   • Reticuloendothelial stores (haemosiderin and ferretin) depleted before anaemia develops
   • Causes
     • Chronic Blood Loss
       • Uterine
       • Gastrointestinal
         • Peptic ulcer disease
         • Aspirin/NSAIDs
         • Malignancy
         • Inflammatory bowel disease
         • Hookworm
       • Haematuria
     • Increased demand
       • Prematurity
       • Pregnancy
       • Growth
     • Malabsorption
       • Coeliac disease
       • Gastrectomy
     • Poor diet