From the Guidelines
A white blood cell (WBC) count of 2.2 × 10^9/L indicates leukopenia, which requires prompt evaluation and management. This patient should be assessed for infection risk, potential causes, and may need immediate medical attention. Common causes include viral infections, certain medications (chemotherapy, antibiotics like trimethoprim-sulfamethoxazole), bone marrow disorders, autoimmune conditions, or nutritional deficiencies. According to the clinical practice guidelines for evaluation of anemia 1, a complete blood count (white blood cells, hemoglobin, and platelets) assesses bone marrow function, and abnormalities in two or more of these cell lines should be evaluated carefully and likely warrant discussion with a hematologist. Management includes identifying and treating the underlying cause, possibly discontinuing offending medications, and monitoring for infection. If neutropenic (absolute neutrophil count <1000/mm³), infection precautions are necessary, including avoiding crowds, maintaining good hygiene, and seeking immediate medical attention for fever (>38°C or 100.4°F). Some key points to consider in the management of leukopenia include:
- Identifying the underlying cause of leukopenia
- Discontinuing any offending medications
- Monitoring for infection
- Implementing infection precautions if neutropenic
- Considering the use of granulocyte colony-stimulating factors like filgrastim (Neupogen) in cases of severe neutropenia. Leukopenia is concerning because white blood cells are crucial for fighting infections, and their reduction significantly increases infection susceptibility, particularly bacterial and fungal infections that can become life-threatening in neutropenic patients.
From the Research
White Blood Cell Count
- A white blood cell (WBC) count of 2.2 is considered low, as a normal WBC count typically ranges from 4,500 to 11,000 cells per microliter [ 2 ].
- Low WBC counts can be caused by various factors, including certain medications, infections, and bone marrow disorders.
Medication-Induced Low WBC Count
- Sulfamethoxazole/trimethoprim, an antibiotic, has been reported to cause agranulocytosis, a potentially life-threatening condition characterized by a low WBC count [ 2 ].
- Another study found that trimethoprim/sulfamethoxazole prophylaxis was associated with a higher incidence of Clostridium difficile enterocolitis and infections caused by gram-negative bacilli, as well as a trend toward prolongation of granulocytopenia [ 3 ].
Bone Marrow Transplantation and WBC Count
- Bone marrow transplant recipients often experience severe immunodeficiency, which can lead to low WBC counts [ 4 ].
- Chemoprophylaxis with oral fluorinated quinolones can help prevent colonization and infection with gram-negative bacilli in these patients [ 4 ].