The clinical approach to anaemia

• Quickly assess for evidence of acute blood loss and haemodynamic instability
• Any of the following: ^HR, v BP, v Urine output (signs of shock)
• Excessive rectal or vaginal bleeding, malaena
• Trauma or post-op (surgical trauma)

Assess the chronicity of the symptoms

• Acute - acute bleed, ABO incompatibility
• Sub-acute - chronic bleed from GI or gynae lesion, immune mediate haemolysis, drug-related
• Chronic - nutritional, haematological malignancy

Assess for causes of chronic blood loss

• History of heavy menstruation, rectal bleeding, malaena (less common causes are bleeding into body cavities)
• History of GI lesions e.g. peptic ulcer, inflammatory disease
• Cause of GI lesions e.g. NSAID, alcohol use
• Identify anaemias of chronic disease (AOCD)
• History of renal failure (inadequate erythopoietin)
• Chronic illness
• Malignancy
• Hypothyroidism

Assess for clotting disorder (consider this for any spontaneous bleeding)

• History of liver disease or anticoagulant use
• History of prolonged bleeding or unexpected bruising

Assess for malabsorptive or nutritional

• Inquire about adequacy or completeness of diet e.g. iron sources, vitamin intake
• Malabsorptive symptoms (staetorhrrea)
• Malabsorptive conditions (including GIT surgery)
• Evidence of malnutrition - weight loss, bruising, neurological symptoms

Assess for haemoglobinopathy

• Family history of anaemia, RBC abnormality
• Previous anaemia or transfusions
• Ethnicity e.g. African - sickle cell, Mediterranean/SE Asian - thallasaemia

Assess for haemolysis

• Recent febrile illness
• Evidence of valve lesion - valvular defects, valve replacement, new murmur
• Hypersplenism e.g. liver disease + portal hypertension
• ABO incompatibility or Rhesus iso-immunisation
• ^ lactate dehydrogenase, ^bilirubin, v haptoglobin, ^ RBC on dipstick, urinary haemoglobin

Assess for bone marrow depression

• drug history e.g. chloramphenicol
• history of haematological malignancy or malignant infiltration
• evidence of haematological disorder - bruising (platelets), recurrent infections (WBCs), lymphadenopathy (lymphoid), bone pain

Determine severity

• Hb level
• Rate of Hb fall
• Degree of functional impairment (e.g. SOB, angina, poor exercise tolerance)

Analyse RBC indices and investigate accordingly

• Microcytic (Iron deficiency, Thallasaemia)- Normocytic (AOCD, Hypothyroid)- Macrocytic (B12, folate, alcohol use, Hypothyroid)

Management

• Treat cause!
• Don't transfuse until all lab investigations have been obtained
• Transfuse if actively bleeding with rapid fall in Hb, significant functional imparment or Hb < 70g/dL, significant cardiorespiratory disease and Hb < 100g/dL
• Transfusion for immune haemolysis may be futile and/or dangerous (may require immunomodulation with gamma-globulin, steroids or plasmapheresis)
• Consider endoscopy / colonoscopy if anaemia unable to be explained