Differential Diagnosis of Anaemia

The differential diagnosis of anaemia is broad and can be categorized based on the likelihood and potential impact of missing a diagnosis. Here's a structured approach:

• Single Most Likely Diagnosis

  • Iron deficiency anaemia: This is the most common cause of anaemia worldwide, often due to chronic blood loss (e.g., menstrual bleeding, gastrointestinal bleeding) or inadequate iron intake.

• Other Likely Diagnoses

  • Vitamin B12 deficiency anaemia: Common in the elderly or those with dietary restrictions (e.g., vegans), leading to megaloblastic anaemia.
  • Vitamin B9 (Folate) deficiency anaemia: Similar to B12 deficiency, often seen in pregnancy, alcoholism, or certain medications.
  • Anaemia of chronic disease: Associated with chronic infections, inflammation, or malignancy, where the body's iron is sequestered and not available for erythropoiesis.
  • Thalassemia: A genetic disorder affecting haemoglobin synthesis, more common in certain ethnic groups.

• Do Not Miss Diagnoses

  • Sickle cell disease: A genetic disorder that can cause severe anaemia, infections, and other systemic complications if not promptly diagnosed and managed.
  • Haemolytic anaemias (e.g., autoimmune haemolytic anaemia, paroxysmal nocturnal haemoglobinuria): Conditions where red blood cells are destroyed faster than they can be made, potentially life-threatening.
  • Leukaemia or lymphoma: Malignancies that can present with anaemia among other symptoms, requiring urgent diagnosis and treatment.
  • Lead poisoning: Though rare, can cause microcytic anaemia and has significant health implications, especially in children.

• Rare Diagnoses

  • Porphyrias: A group of disorders that can lead to anaemia due to defects in haem synthesis.
  • Myeloproliferative neoplasms (e.g., polycythaemia vera, essential thrombocythaemia): Though more often associated with increased blood cell counts, can occasionally present with anaemia.
  • Inherited disorders of iron metabolism (e.g., hereditary haemochromatosis, atransferrinemia): Rare conditions affecting iron absorption or utilization.
  • Anaemia associated with endocrine disorders (e.g., hypothyroidism, Addison's disease): Though not the primary presentation, can be a contributing factor to anaemia in these conditions.

Each of these diagnoses has a distinct set of causes, symptoms, and implications for patient management, highlighting the importance of a thorough diagnostic approach to anaemia.