White blood cells

Looks like

Colourless cells with a nucleus, larger than red cells and far fewer — about one for every 700 red cells.

What it does

Defend the body against infection and clear dead cells and debris.

Keeping it well

A very low count raises the risk of serious infection; fever during chemotherapy is an emergency. A very high count needs checking for infection or leukaemia.

Its parts

• Neutrophils
• Lymphocytes
• Monocytes & macrophages
• Eosinophils & basophils

Related conditions

• Acute leukaemia (AML & ALL)
• African trypanosomiasis (sleeping sickness)
• Aplastic anaemia & marrow failure
• Chronic leukaemia (CML & CLL)
• Clotting disorders (thrombophilia & APS)
• Dehydration & electrolyte disorders
• Delirium
• Dengue & mosquito-borne fevers
• Diabetic ketoacidosis
• Disseminated intravascular coagulation
• Ebola virus disease
• G6PD deficiency (favism)
• Haemophilia & bleeding disorders
• Hereditary spherocytosis
• High cholesterol
• HIV infection
• Lymphoma (Hodgkin & non-Hodgkin)
• Malnutrition & refeeding syndrome
• Maternal (puerperal) sepsis
• MGUS (monoclonal gammopathy)
• MRSA and resistant staph infection
• Multiple myeloma
• Myelodysplastic syndromes
• Neonatal sepsis
• Neutropenic sepsis
• Postpartum haemorrhage
• Primary immunodeficiency
• Scrub typhus & rickettsial infections
• Sepsis
• Shock (circulatory failure)
• Toxic shock syndrome
• Transplant rejection & graft-versus-host disease
• Typhoid & cholera
• Vitamin B1, C and other deficiencies
• Vitamin D deficiency
• Von Willebrand disease