Corticosteroid-Induced Leukocytosis

Mechanism and Characteristics

• The American Society of Clinical Oncology identifies corticosteroids as lymphocyte-depleting therapy, which can cause leukocytosis, a well-established and dose-dependent effect that can occur as early as the first day of treatment and persist throughout therapy, with a predominantly neutrophilic pattern 1, 2, 3

Clinical Implications for Practice

• The ASCO guideline recommends being aware that corticosteroids can cause leukocytosis, and to distinguish it from infection by checking the peripheral smear for left shift and toxic granulation, considering the magnitude of increase, and assessing clinical context, with the understanding that even small doses of prednisone administered over prolonged periods can induce extreme and persistent leukocytosis 1, 2, 3

Steroid-Induced Leukocytosis

Clinical Presentation and Management

• The American College of Physicians recommends investigating for infection in patients with WBC >14,000/mm³ and left shift (>6% bands), regardless of steroid dose 4
• Immunosuppressed patients on chronic steroids should be considered for PCP prophylaxis, and a heightened vigilance for occult infection should be maintained even without fever 4

Special Considerations

• Leukocytosis may be blunted or absent in immunocompromised patients or those taking steroids, making infection diagnosis more challenging 4

Corticosteroid-Induced Leukocytosis

Mechanism and Effects

• Corticosteroids, such as methylprednisolone, are lymphocyte-depleting agents, causing a decrease in lymphocyte counts while neutrophils increase 5

Clinical Implications and Monitoring

• The European Society of Gastroenterology recommends monitoring for neutrophilia when patients receive IV methylprednisolone, such as 100 mg every 6 hours for acute severe ulcerative colitis, with expected WBC elevation within 6-24 hours 6
• The American Society of Clinical Oncology suggests that serial monitoring of WBC counts with differential is necessary if infection is suspected in patients on high-dose steroids, rather than relying on a single elevated value 5
• The National Comprehensive Cancer Network recommends considering Pneumocystis jirovecii prophylaxis for patients on chronic high-dose steroids, and maintaining vigilance for opportunistic infections 5

Corticosteroid-Induced Leukocytosis

Dose and Duration Effects

• The American Gastroenterological Association suggests that corticosteroid therapy at any dose for less than 1 week carries low risk for significant immunosuppression but still produces measurable leukocytosis 7
• The American Society of Clinical Oncology recommends that standard ITP treatment with prednisone 0.5-2 mg/kg/day for 2-4 weeks produces consistent leukocytosis throughout the treatment period 8, 9, 10
• The American Gastroenterological Association indicates that moderate-to-high dose prednisone for 4 weeks or more produces sustained leukocytosis and increases infection risk, warranting consideration for Pneumocystis jirovecii prophylaxis 7
• The American Gastroenterological Association suggests that low-dose prednisone for 4 weeks or more in certain patient populations carries moderate risk for viral reactivation, indicating sustained immunologic effects 7

Risk Stratification

• The American Gastroenterological Association recommends that moderate-to-high dose prednisone for 4 weeks or more requires PCP prophylaxis and heightened infection surveillance 7
• The American Gastroenterological Association suggests that low-dose prednisone for 4 weeks or more in certain patient populations is considered a moderate-risk category 7
• The American Gastroenterological Association indicates that any dose for less than 1 week duration is considered a low-risk category 7

Corticosteroid-Induced Leukocytosis

Clinical Implications and Monitoring

• In inflammatory bowel disease patients, glucocorticoids increase WBC count, while other immunosuppressive drugs decrease WBC count, according to the World Journal of Emergency Surgery guidelines 11

Steroid-Induced Leukocytosis Guidelines

Clinical Implications and Management

• The American Thoracic Society recommends Pneumocystis jirovecii prophylaxis and heightened infection surveillance for patients on moderate-to-high dose prednisone ≥20 mg/day for ≥4 weeks, due to sustained leukocytosis and increased infection risk 12
• Patients taking ≥40 mg prednisolone have greater risks of postoperative infectious complications, and steroids should be stopped or minimized prior to elective surgery wherever possible, with patients on corticosteroids at the time of surgery receiving intravenous hydrocortisone in equivalent dosage until they can resume oral prednisolone 13

Corticosteroid-Induced Leukocytosis

Mechanism and Time Course

• The American Thoracic Society notes that corticosteroids can cause eosinophil counts to decrease 2- to 7-fold with treatment, with effects appearing as early as 6 hours after administration 14
• White blood cell values peak 24 hours after corticosteroids for fetal lung maturity, with a 2 SD from mean of 20.8 × 10⁶/L, and return close to baseline by 96 hours, according to the American College of Obstetricians and Gynecologists 15

Pattern of Cell Type Changes

• The American Journal of Respiratory and Critical Care Medicine reports that eosinophil counts decrease with corticosteroid treatment, with a decrease of 2- to 7-fold 14

Special Considerations in Asthma and Inflammatory Conditions

• The American Thoracic Society notes that while total WBC increases, eosinophil counts paradoxically decrease with corticosteroid therapy, with sputum eosinophil counts decreasing 2- to 7-fold with corticosteroid treatment 14