From the Guidelines
A mild decrease in white blood cell (WBC) count can be caused by several factors, including certain medications such as azathioprine and cyclophosphamide, as well as corticosteroid therapy. According to the American Thoracic Society guidelines 1, azathioprine and cyclophosphamide can cause a decrease in WBC count, and the dose of these medications should be adjusted or stopped if the WBC count falls below 4,000/mm3. Additionally, corticosteroid therapy can suppress the immune response to skin tests and may increase the risk of infections such as Pneumocystis carinii and Mycobacterium tuberculosis 1.
Other factors that can cause a mild decrease in WBC count include:
- Viral infections, such as influenza, HIV, and hepatitis, which can temporarily suppress bone marrow function
- Autoimmune disorders, such as lupus and rheumatoid arthritis, which can cause the body to attack its own white blood cells
- Nutritional deficiencies, particularly vitamin B12, folate, or copper deficiency, which can impair proper WBC production
- Bone marrow disorders, which can sometimes present with mild reductions in WBC count initially
- Congenital conditions, such as benign ethnic neutropenia, which can cause naturally lower but still functional WBC levels
- Stress, both physical and psychological, which can temporarily decrease WBC counts through cortisol release
It's also worth noting that certain medications, such as clozapine, can cause a decrease in WBC count, and regular monitoring of blood cell counts is recommended when using this medication 1. In general, a mild decrease in WBC count does not require treatment unless there are symptoms of infection or the underlying cause needs to be addressed.
From the FDA Drug Label
Adverse reactions with ≥ 5% higher incidence in filgrastim patients compared to patients receiving no filgrastim included ... anemia The FDA drug label does not answer the question about what can cause a mild decrease in a WBC, but it does mention anemia as an adverse reaction, which can be associated with a decrease in red blood cells, not white blood cells. However, the label does not provide information on what can cause a mild decrease in WBC. Key points:
- The label mentions various adverse reactions, but none of them directly relate to a mild decrease in WBC.
- Anemia is mentioned as an adverse reaction, but it is related to a decrease in red blood cells, not white blood cells. 2
From the Research
Causes of Mild Decrease in WBC
- Beta-lactam antibiotics can cause a mild decrease in White Blood Cell (WBC) count, as seen in a study where two patients developed neutropenia while receiving beta-lactam antibiotics 3
- The mechanism of this decrease is thought to be an immunologic reaction characterized by rapid destruction of peripheral neutrophils 3
- Other studies have shown that beta-lactam antibiotics can cause immune thrombocytopenia, which may also be related to a decrease in WBC count 4
- The use of beta-lactam antibiotics can lead to the development of antimicrobial resistance, which may also affect WBC count 5
- Hypersensitivity reactions to beta-lactam antibiotics can also cause a decrease in WBC count, and can be mediated by IgE or T-cell dependent mechanisms 6
Beta-Lactam Antibiotics and WBC Decrease
- Penicillins, cephalosporins, monobactams, carbapenems, and clavams are all types of beta-lactam antibiotics that can cause a decrease in WBC count 6
- The structural aspects of these antibiotics, such as their stability and sensitivity to beta-lactamases, can affect their mechanism of action and spectrum of antimicrobial activity 7
- The use of beta-lactamase inhibitors can help to circumvent resistance issues and may also affect WBC count 7