Neutropenia is a granulocyte disorder characterized by an abnormally low number of nentrophils. Neutrophils usually make up to 50-70% of circulating white blood cells. Hence, patients with neutropenia are more susceptible to bacterial infections and, without prompt medical attention, the condition may become life-threatening (neutropenic sepsis).
It can be acute or chronic depending on the duration of the illness. It is chronic if condition lasts for longer than 3 months, it is sometimes used interchangeably with the term leucopenia “deficit in the number of WBCs”.
Classification of Neutropenia
There are general guidelines used to classify the severity of neutropenia based on the absolute neutrophil count (ANC) measured in cell per microliter of blood (Hsieh et al., 2007).
- Mild neutropenia (1000 ≤ ANC < 1500) minimal risk infection
- Moderate neutropenia (500 ≤ ANC < 1000) moderate risk of infection
- Severe neutropenia (ANC < 500) severe risk of infection.
Note: A large proportion of healthy African have been observed to have a white blood cell count (WBC) that is persistently lower than the normal range defined for individuals of European ancestry (Forbes et al., 1914, Broun et al., 1966, Van Assendelft, 1985, Hsieh et al., 2007 and Haddyet al., 1999). This condition called “Benign Ethnic Neutropenia” (BEN). BEN can have important effect on medical decision making, since WBC is a valuable indicator of immunocompetence, infection and inflammation. The etiology of BEN is not well understood, but the mechanism for it does not appear to represent a biological abnormality.
About half of the neutrophils in blood, circulate to form circulating pool (included in WBC count) while the other half migrate along the walls of the blood vessels and capillaries, forming marginated pools (not included in WBC count). Increased number of neutrophil in the marginating pool may explain the lower circulating neutrophil count in Africans (Monica, 2000).
Signs and Symptoms
Neutropenia can go undetected, but is generally discovered when a patient has developed severe infections or sepsis. Some common infection can take an undetected course in neutropenic patients; formation of pus, for example, can be notably absent, as this requires circulating neutrophil granulocytes. Common symptoms include:
- Frequent infections, that can result in conditions such as;
- Mouth ulcers
- Burning sensation when urinating
- Unusual redness
- Swelling around a wound
- Sore throat.
Neutropenia can be detected on;
- Full blood count (FBC).
- Bone marrow biopsy i.e when other diagnosis are uncertain or serious causes are suspected.
- Other investigations;
- Serial neutrophil count (if cyclic neutropenia is suspected)
- Test for anti-neutrophil antibodies
- Autoantibody screen
- Test for systemic lupus erythematosis, vit B12 and folate assay and acidified serum (Ham’s test) (Levene et al., 2001).