From the Guidelines
Steroids, particularly glucocorticoids like prednisone, dexamethasone, and methylprednisolone, typically cause an increase in white blood cell (WBC) counts, especially neutrophils, due to their effects on neutrophil migration, adhesion, and apoptosis, as well as stimulation of neutrophil release from the bone marrow storage pool into circulation. This phenomenon, called steroid-induced leukocytosis, can elevate WBC counts to 10,000-20,000 cells/μL or higher, even in the absence of infection 1. The increase is predominantly in neutrophils, while other white cell types like lymphocytes may actually decrease.
Mechanism of Action
The WBC increase occurs because steroids inhibit neutrophil migration out of the bloodstream and into tissues, reduce neutrophil adhesion to vessel walls, and delay neutrophil apoptosis (programmed cell death) 1. Additionally, steroids can stimulate the release of neutrophils from the bone marrow storage pool into circulation. This effect is usually seen within 24 hours of starting steroid therapy and can persist throughout treatment.
Clinical Implications
Healthcare providers should be aware of this effect when interpreting blood tests in patients on steroid therapy to avoid misdiagnosing infection or other inflammatory conditions. The WBC elevation is a normal physiological response to steroids and typically resolves after discontinuation of the medication. However, it is essential to monitor patients on steroid therapy for signs of infection, as corticosteroids may increase the risk of infection, particularly in patients with underlying cirrhosis or immunodeficiency 1.
Key Points
- Steroids cause an increase in WBC counts, especially neutrophils
- The increase is due to inhibition of neutrophil migration, adhesion, and apoptosis, and stimulation of neutrophil release from the bone marrow
- WBC elevation is a normal physiological response to steroids and typically resolves after discontinuation of the medication
- Healthcare providers should be aware of this effect to avoid misdiagnosing infection or other inflammatory conditions
- Patients on steroid therapy should be monitored for signs of infection, particularly those with underlying cirrhosis or immunodeficiency 1
From the Research
Causes of Increased White Blood Cell Count
The increase in White Blood Cell (WBC) count in patients taking steroids (corticosteroids) can be attributed to several factors, including:
- The dosage and duration of corticosteroid administration 2, 3
- The type of corticosteroid used, such as prednisone 3 or inhaled corticosteroids like budesonide and fluticasone 4
- The individual patient's response to corticosteroids, which can be variable and unpredictable 5
Mechanisms of Leukocytosis
The mechanisms underlying corticosteroid-induced leukocytosis include:
- Increased release of neutrophils from the bone marrow 2, 4
- Decreased adhesion of neutrophils to the endothelial surface, mediated by decreased expression of adhesion molecules like Mac-1 and L-selectin 4
- Demargination of neutrophils from the vascular endothelium 2
Clinical Implications
The increase in WBC count in patients taking corticosteroids can have significant clinical implications, including:
- Difficulty in distinguishing between corticosteroid-induced leukocytosis and infection-induced leukocytosis 2, 3
- Potential for misinterpretation of WBC counts, leading to inappropriate clinical decisions 4
- Need for careful monitoring of WBC counts and differential cell counts in patients receiving corticosteroids 5