From the Guidelines
Steroids, particularly glucocorticoids like prednisone, dexamethasone, and methylprednisolone, commonly cause an increase in white blood cell (WBC) count, specifically neutrophils, due to their effects on neutrophil migration, apoptosis, and release from bone marrow reserves. This phenomenon, known as steroid-induced leukocytosis, typically occurs within 24-48 hours after starting steroid therapy and can elevate WBC counts to 10,000-20,000 cells/μL or higher 1. The increase is dose-dependent and resolves gradually after discontinuation of the medication.
Key Points to Consider
- Steroids can cause a decrease in lymphocytes, eosinophils, and monocytes, creating a characteristic pattern on differential counts 1.
- The risk of infection associated with corticosteroid use is a concern, particularly in patients with severe alcoholic hepatitis, where bacterial infections represent the vast majority of infectious episodes 1.
- However, a recent meta-analysis has shown that patients treated with corticosteroids had no increased risk of infection or higher mortality from infection than those treated with placebo 1.
- It's essential to recognize steroid-induced leukocytosis as an expected pharmacologic effect rather than a sign of infection, though clinicians should still consider other causes of leukocytosis when evaluating patients on steroid therapy, especially if accompanied by fever or other signs of infection.
Clinical Implications
- Clinicians should be aware of the potential for steroid-induced leukocytosis and consider this when interpreting WBC counts in patients on steroid therapy.
- Careful screening for infection is recommended before initiating corticosteroid therapy, repeatedly during treatment, and during the follow-up period, especially in high-risk patients 1.
- The presence of an infection at baseline does not appear to contraindicate steroid therapy if the infectious episode is well treated and ‘controlled’ 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