Anaemia

Overview 

The World Health Organization defines anaemia as a haemoglobin (Hb) concentration below 13 g/dl (130 g/L) in men over 15 years of age, below 12 g/dl (120g/L) in non-pregnant women over 15 years of age, and below 11 g/dl (110g/L) in pregnant women. There are many causes of anaemia. It is important to take a comprehensive history, examination and inspect FBC and blood films.

Remember Anaemia men: 130g/L and in women: 120g/L

Physiology of RBCs

Watch: Haematology – Red Blood Cells

 

Watch: Haematology – RBC life cycle

Approach

• History
  • Symptoms of Anaemia (fatigue, shortness of breath)
  • Sleeping – Obstructive sleep Apnoea
  • Pancytopaenia (easy bruising, bleeding, infections)
  • Family History of haemolytic disease
  • Menstrual history: menorrhagia, menometrorrhagia
  • Connective Tissue disorder
  • Neurological symptoms
  • Medication history
  • Ethnic background
  • Medical condition
  • Surgical history – heart valve surgery associated with haemolysis
• Examination
  • Jaundice
  • Pallor
  • Splenomegaly
  • Hepatomegaly
  • Signs of connective tissue disease

Investigations 

If anaemia is suspected begin with:

• Full blood examination
• Iron studies
• Serum vitamin B12/folate
• Peripheral Blood film
• Reticulocyte count

Reticulocytes are immature erythrocytes and are markers of erythrocyte production. The reticulocyte count should always be interpreted in the context of the Hb. Should normally increase when there is a decrease in RBC.

1. The first step in diagnosing the cause of anaemia is to find out the mean cell volume (MCV). The initial classification is based on the MCV:
   • Microcytic Anaemia
   • Normocytic Anaemia
   • Macrocytic Anaemia
2.  Any further investigations will be determined by the blood film appearance and clinical suspicion

DIFFERENT TYPES OF ANAEMIA BASED ON MCV
Microcytic Anaemia	Normocytic Anaemia	Macrocytic Anaemia
Iron-deficiency	Anaemia of chronic disease (MCV may be reduced)	Vitamin B12 deficiency
Thalasaemia	Haemolytic anaemia (hemolysis)	Alcohol excess
Sideroblastic anaemia	Acute blood loss	Reticulocytosis
	Bone marrow failure/CKD	Myelodysplastic syndrome
	Hypothyroidism	Myeloproliferative disorders
	Pregnancy	Hypothyroidism
		Folate deficiency

Side Note Bone marrow failure induced anaemia is also known as Aplastic Anaemia.