Definition of Neutropenia
Neutropenia is a condition in which the count of neutrophils is reduced. White blood cells fight against the infections caused by microorganisms. Human blood consists of many types of white blood cells, including lymphocytes, monocytes, basophils, eosinophils, and neutrophils.
Neutrophils are the most abundant, constituting about 40 – 75% of white blood cells (WBC). They are the first cells to move in response to inflammatory chemicals released from damaged or invaded cells.
Neutropenia can occur as a result of the following conditions:
- A child not making enough neutrophils
- Excessive neutrophils are getting destroyed in the circulation
- Defective neutrophils accumulate in improper places instead of migrating through proper channels
Neutropenia is defined differently in infants (up until one year of age) and older children. In infants, a count lower than 1000/ul is defined as neutropenia. In children older than one year of age, the definition is the same as that of adults (lower than 1,500/ul).
Classification of Neutropenia
- In mild neutropenia, the ANC (absolute neutrophil count) is 1000—1500/ul.
- In moderate cases, the ANC ranges from 500—1000/ul
- In severe neutropenia, it is < 500/ul
ANC = WBC/microlitre x percent (Polymorphonuclear cells + bands)/100
Types of Neutropenia
There are three types of neutropenia – hereditary, acquired, and mixed. The important types in each category are discussed as below.
Also known as congenital neutropenia, it is the most severe type and is is autosomal dominant. It is more common in infants and young children. The symptoms include mouth sores, frequent fever, pneumonia, ear infections, and rectal sores. If the condition is not treated immediately, a child may begin losing teeth due to severe gum infections.
Kostmann’s Syndrome is a chronic sub-type of hereditary neutropenia. It is an aggressive condition, transmitted in an autosomal recessive pattern.
This sub-type is present among family members. It occurs every three weeks (the range can be from 12–35 days) and continues for 3–6 days in a single cycle. The symptoms include infections, fever, and ulcers. Most children improve after puberty.
Acquired types are more common than hereditary types.
Drug-induced: A drug can act as a hapten and induce antibody formation. The drugs that can cause neutropenia are Quinidine, Aminopyrine, Penicillin, Cephalosporin, Phenothiazines, Sulfonamides, and Hydralazine.
Autoimmune: Neutropenia can be primary or secondary autoimmune neutropenia. In the primary form, there is no other abnormality except the antibodies (antineutrophil antibodies) that attach to neutrophils, causing their peripheral destruction; infections that occur as a result of neutropenia are mild and limited.
Secondary autoimmune neutropenia occurs due to some other primary pathology, like other autoimmune diseases, infections, or malignancy. In infants, secondary neutropenia is very rare, but its incidence increases after one year of age. Therefore, rigorous research to find the underlying autoimmune diseases is needed.
The following are the infections that can result in the acquired form of neutropenia:
- Viral infections (Measles, influenza, EBV, CMV, Viral hepatitis, HIV)
- Bacterial sepsis
- Rickettsial infection
- Dengue Fever
Mixed type of Neutropenia
Chronic Benign Neutropenia
It is a rare form that can lead to life-threatening infections. It is more common in children under four years of age. The infections tend to decrease with age.
Causes of Neutropenia
- Aplastic anemia
- Tumor infiltration
- Ionizing radiation
- Bacterial infections
- Viral infections
Signs and Symptoms of Neutropenia
The signs and symptoms are those of the infections that have occurred due to neutropenia:
- Otitis media
- Bladder infection
- Sore throat
- Gum infections
Diagnosis of Neutropenia
The diagnosis is based on history, physical examination, and laboratory investigations. Imaging studies are also performed in certain cases.
The child often has complaints of pneumonia, ear infection, tonsillitis, gastroenteritis, skin infection, and pharyngitis. Family history is important, especially in cases of inherited neutropenia.
Symptoms include signs of infection, fever, ulcers, gingivitis, abscesses, pneumonia, skin infections, sepsis, cervical lymphadenopathy, and growth retardation. There is often a fever without any focal signs of the disease.
- Complete blood count
- Differential Leukocyte Count (DLC)
- Peripheral blood smears
- Liver function tests
- Antineutrophil antibody tests
- Rheumatoid factor (RF)
- Quantification of serum immunoglobulin
- Peripheral blood flow cytometry
- Other tests for infections (mentioned in types) such as Typhoid, TB, Hepatitis, and AIDS
Urine culture, blood cultures, wound cultures, sputum cultures, Gram-staining, skin biopsy, and stool cultures for Clostridium Difficile. The list can vary depending upon the type of infection.
- Radiographs of long bones for cases of congenital neutropenia
- Chest X-rays and CT scans for signs of pneumonia
- Abdominal radiographs of the liver and spleen
Management of Neutropenia
There is a general approach and specific treatment for neutropenia.
- Remove offending drugs
- Oral hygiene
- Stool softeners
- Correction of folic acid deficiency
- Dietary measures to include properly cooked meat, clean water and no acidic foods
- Colony-stimulating factors
- Granulocyte transfusion