Does steroid (corticosteroid) therapy increase White Blood Cell (WBC) count?

From the Guidelines

Yes, steroids can increase white blood cell (WBC) count, as they stimulate the release of neutrophils from bone marrow reserves and reduce their migration out of the bloodstream, thereby increasing the total WBC count [ 1 ].

Mechanism of Action

The mechanism of this increase involves the effects of corticosteroids on various cell types in the blood.

• Corticosteroids like prednisone, dexamethasone, and methylprednisolone cause an elevation in total WBC count within hours of administration.
• This increase primarily affects neutrophils, while simultaneously decreasing lymphocytes, eosinophils, and monocytes.
• Additionally, steroids delay neutrophil apoptosis (programmed cell death), allowing them to remain in circulation longer.

Clinical Implications

This effect is dose-dependent and usually temporary, with WBC counts returning to baseline after the steroid is discontinued [ 1 ].

• The WBC elevation from steroids is a normal physiological response and should not be confused with an infection.
• However, it can make interpreting blood tests challenging when monitoring for infection in patients on steroid therapy.
• Healthcare providers typically account for this effect when evaluating blood work in patients taking corticosteroids.

Evidence Summary

The provided evidence does not directly address the question of steroid effects on WBC count, but it discusses the immunosuppressive effects of corticosteroids and their potential to reactivate hepatitis B [ 1 ].

• Another study discusses the use of corticosteroids in the treatment of immune thrombocytopenia, but does not address their effect on WBC count [ 1 ].
• However, based on general medical knowledge, it is well established that corticosteroids can increase WBC count, and this effect should be considered when interpreting blood tests in patients taking these medications.

From the Research

Effect of Steroids on White Blood Cell Count

• Steroids have been shown to increase white blood cell (WBC) count in various studies 2, 3, 4.
• The increase in WBC count is attributed to an increase in polymorphonuclear white blood cells, monocytosis, eosinopenia, and a variable degree of lymphopenia 3.
• The degree of leukocytosis is related to the dosage of steroids administered, with higher doses resulting in greater increases in WBC count 2, 3.
• The WBC response to steroids peaks at 48 hours after administration, with a mean increase of 2.4 × 10^9/L WBCs 2.
• Inhaled corticosteroids have also been shown to increase WBC count by decreasing the expression of neutrophil adhesion molecules Mac-1 and L-selectin 4.

Mechanisms of Steroid-Induced Leukocytosis

• The exact mechanisms of steroid-induced leukocytosis are not fully understood, but it is thought to be related to the effects of steroids on neutrophil adhesion and migration 4.
• Steroids may decrease the expression of adhesion molecules on neutrophils, leading to an increase in circulating neutrophils 4.
• The increase in WBC count may also be related to the effects of steroids on the bone marrow, although this is not fully understood 5.

Clinical Implications

• The increase in WBC count caused by steroids can make it difficult to diagnose infections, particularly in immunocompromised patients 3.
• Clinicians should be aware of the potential for steroids to increase WBC count and interpret laboratory results accordingly 2, 4.