Can long-term use of prednisone (corticosteroid) cause an increase in segmented neutrophils (segs) and lymphocytes (lymphs) on a complete blood count (CBC)?

Effects of Long-Term Prednisone on CBC: Impact on Segmented Neutrophils and Lymphocytes

Long-term prednisone use can cause an increase in segmented neutrophils (segs) but typically causes a decrease in lymphocytes, not an increase in lymphocytes, on complete blood count (CBC). 1

Prednisone Effects on White Blood Cell Counts

Neutrophil Effects

• Prednisone consistently causes neutrophilia (increased neutrophil count), including segmented neutrophils
• This effect:
  • Occurs as early as the first day of treatment 1
  • Can persist for the duration of therapy
  • May result in white blood cell counts exceeding 20,000/mm³ 1
  • Reaches maximal values within two weeks in most cases
  • Is dose-dependent, though even small doses can induce significant leukocytosis 1

Lymphocyte Effects

• Prednisone typically causes lymphopenia (decreased lymphocyte count), not lymphocytosis 1, 2
• Studies show:
  • Marked lymphopenia occurs within hours after prednisone ingestion 2
  • Lymphocyte counts may return to normal or higher by 24 hours in patients on alternate-day dosing 2
  • Lymphocyte suppression can persist for weeks after treatment cessation 3

Time Course of Changes

• Acute effects (within hours):

  • Significant increase in white blood cell count (average +2,400 cells/mm³) 4
  • Changes primarily due to increased segmented neutrophils and decreased lymphocytes 4
  • Individual responses vary widely (from -600 to +8,000/mm³) 4

• Long-term effects:

  • Leukocytosis tends to decrease over time but typically remains above pretreatment levels 1
  • Lymphocyte counts may remain suppressed for up to 4 weeks after treatment cessation 3

Clinical Implications

• These changes can complicate the diagnosis of infection in patients on prednisone therapy 1
• When infection is suspected in patients on prednisone:
  • Look for a shift to the left (>6% band forms)
  • Check for toxic granulation in neutrophils
  • These findings suggest infection rather than just prednisone-induced leukocytosis 1

Monitoring Recommendations

• CBC with differential should be obtained before the morning prednisone dose to avoid misinterpretation due to acute steroid-induced changes 4
• Regular monitoring is important as individual patient responses to the same dose of prednisone are reproducible but vary significantly between patients 4

Other Hematologic Effects

• Prednisone also typically causes:
  • Monocytosis (increased monocyte count) 1
  • Eosinopenia (decreased eosinophil count) 1, 3
  • Variable effects on platelet parameters 3

In conclusion, while long-term prednisone use consistently causes an increase in segmented neutrophils, it typically causes a decrease in lymphocytes rather than an increase. The pattern of increased neutrophils with decreased lymphocytes is a characteristic finding in patients on chronic prednisone therapy.