Neutropenia

Neutropenia
Classification and external resources
Blood film with a striking absence of neutrophils, leaving only red blood cells and platelets
ICD-10	D70
ICD-9	288.0
DiseasesDB	8994
eMedicine	med/1640
MeSH	D009503

Neutropenia, occasionally spelled neutropaenia or neutropoenia, from Latin prefix neutro- (neither, for neutral staining) and Greek suffix -πενία (deficiency), is a granulocyte disorder characterized by an abnormally low number of neutrophils. Neutrophils usually make up 50-70% of circulating white blood cells and serve as the primary defense 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 and deadly (neutropenic sepsis).

Neutropenia can be acute or chronic depending on the duration of the illness. A patient has chronic neutropenia if the condition lasts for longer than three months. It is sometimes used interchangeably with the term leukopenia ("deficit in the number of white blood cells"), as neutrophils are the most abundant leukocytes, but neutropenia is more properly considered a subset of leukopenia as a whole.

There are numerous causes of neutropenia that can roughly be divided between either problems in the production of the cells by the bone marrow and destruction of the cells elsewhere in the body. Treatment depends on the nature of the cause, and emphasis is placed on the prevention and treatment of infection.

Classification

There are three general guidelines used to classify the severity of neutropenia based on the absolute neutrophil count (ANC) measured in cells per microliter of blood:^[1]

• 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.

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 fevers and frequent infections. These infections can result in conditions such as mouth ulcers, diarrhea, a burning sensation when urinating, unusual redness, pain, or swelling around a wound, or a sore throat.

Diagnosis

Low neutrophil counts are detected on a full blood count. Generally, 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.

Other investigations commonly performed: serial neutrophil counts for suspected cyclic neutropenia, tests for antineutrophil antibodies, autoantibody screen and investigations for systemic lupus erythematosus, vitamin B₁₂ and folate assays and acidified serum (Ham's) test.^[2]

Causes

Causes can be divided into the following groups:

• Decreased production in the bone marrow due to:
  • aplastic anemia
  • arsenic poisoning^[3]
  • cancer, particularly blood cancers
  • certain medications
  • hereditary disorders (e.g. congenital neutropenia, cyclic neutropenia)
  • radiation
  • Vitamin B₁₂, folate or copper deficiency.
• Increased destruction:
  • autoimmune neutropenia.
  • chemotherapy treatments, such as for cancer and autoimmune diseases
• Marginalisation and sequestration:
  • Hemodialysis
• Medications
  • Flecainide (a class 1C cardiac anti-arrhythmic drug)
  • phenytoin
  • indomethacin
  • propylthiouracil
  • carbimazole
  • chlorpromazine
  • trimethoprim/sulfamethoxazole (cotrimoxazole)
  • clozapine
  • ticlodipine

There is often a mild neutropenia in viral infections. Additionally, there is a condition called morning pseudoneutropenia which might be a side effect of certain anti-psychotic medications.

Therapy

There is no ideal therapy for neutropenia, but recombinant G-CSF (granulocyte-colony stimulating factor) such as filgrastim (Neupogen) can be effective in chemotherapy patients, in patients with congenital forms of neutropenia including severe congenital neutropenia, autosomal recessive Kostmann's syndrome, cyclic neutropenia, and myelokathexis. Guidelines given to neutropenic patients regarding diet are currently being studied.^[4]

History

The relationship between a low neutrophil count and increased risk of infection was first demonstrated in patients with leukemia.^[5]

See also

• Aplastic anemia
• Pancytopenia
• Thrombocytopenia

References

External links

• National Neutropenia Network
• Severe Chronic Neutropenia International Registry