Neutropenia is a haematological disorder characterised by an abnormally low number of neutrophil granulocytes (a type of white blood cell). Neutrophils usually make up 50-70% of circulating white blood cells and serve as the primary defence against infections by destroying bacteria in the blood. Hence, patients with neutropenia are more susceptible to bacterial infections and without prompt medical attention, the condition may become life-threatening. Neutropenia can be acute or chronic depending on the duration of the illness. A patient has chronic neutropenia if the condition lasts for greater than 3 months.

Classification

There are four general guidelines used to classify the severity of neutropenia based on the absolute neutrophil count (ANC) measured in cells per microlitre of blood:

• Neutropenia (ANC < 2000) — slight risk of infection
• Mild Neutropenia (1000 < ANC < 1500) — minimal risk of infection
• Moderate Neutropenia (500 < ANC < 1000) — moderate risk of infection
• Severe Neutropenia (ANC < 500) — severe risk of infection.

Types

Severe chronic neutropenia may be present at birth (congenital neutropenia) or may occur at any stage in life (acquired neutropenia). There are four main types of severe chronic neutropenia:

Congenital Neutropenia — a rare inherited form of the disease usually detected soon after birth. It affects children mainly and may result in premature loss of teeth and peremptory gum infections. The most severe form of chronic congenital neutropenia is known as Kostmann’s Syndrome .

Cyclic Neutropenia — tends to occur every three weeks and lasting three to six days at a time due to changing rates of cell production by the bone marrow. It is often present among several members of the same family although improves after puberty in most cases. This is the rarest form of severe chronic neutropenia.

Idiopathic Neutropenia — a rare form of neutropenia which develops in children and adults usually in response to an illness. It is diagnosed when the disorder cannot be attributed to any other diseases and often causes life-threatening infections.

Autoimmune Neutropenia — most common in infants and young children where the body identifies the neutrophils as enemies and makes antibody to destroy them. This form usually lessens in severity within two years of diagnosis.

Signs and symptoms

Neutropenia can go undetected, but is generally discovered when a patient has developed severe infections or sepsis. Some common infections can take an unexpected course in neutropenic patients; formation of pus, for example, can be notably absent, as this requires circulating neutrophil granulocytes.

Some common symptoms of neutropenia include:

• Fever
• Frequent infections due to lessened ability to fight bacterial infections
• Mouth ulcers
• Diarrhoea
• Burning sensation when urinating
• Unusual redness, pain, or swelling around a wound
• Sore throat
• Shortness of breath
• Shaking chills

Diagnosis

Low neutrophil counts are detected on a full blood count. Generally, some other investigations are required to arrive at the right diagnosis. When the diagnosis is uncertain, or serious causes are suspected, bone marrow biopsy is often necessary.

Causes

Causes can be divided into the following groups:

• Decreased production in the bone marrow:
  • hereditary disorders (e.g. congenital neutropenia , cyclic neutropenia )
  • cancer
  • certain medications
  • radiation
  • Vitamin B₁₂ or folate deficiency.
• Increased destruction:
  • Aplastic anemia
  • autoimmune neutropenia.
  • Chemotherapy
• Marginalisation and sequestration:
  • Hemodialysis

There is usually a mild neutropenia in viral infections.

Therapy

There is no ideal therapy for neutropenia, but recombinant G-CSF (granulocyte-colony stimulating factor) can be effective in chemotherapy patients and some other causes.

See also

• Aplastic anemia
• Pancytopenia
• Thrombocytopenia