Classification
There are iv general guidelines utilized to classify a nature and severity of neutropenia according to a absolute neutrophil count (ANC) measured inside cells by the 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.

Drug-induced neutropenia — Many drugs can cause agranulocytosis (complete absence of white cells) and neutropenia. Many anti-neoplastic drugs cause agranulocytosis and neutropenia by bone marrow suppression. Neutropenia and agranulocytosis can also result from antibody or complement-mediated damage to the stem cells. Some drugs may cause increased peripheral destruction of white cells. About 75% of all cases of agranulocytosis in the United States are related to medication. Clozapine, procainamide, anti-thyroid drugs (e.g. methimazole, and sulfasalazine are at the top of the list of drugs causing this problem, but many others (such as antiepileptics) have been implicated.

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.