Can lupus cause elevated white and red blood cell counts?

Lupus and Blood Cell Counts

Lupus typically causes decreased white and red blood cell counts, not elevated counts—if you see elevated counts in a lupus patient, you must actively search for alternative explanations such as infection, malignancy, or medication effects.

White Blood Cell Abnormalities in Lupus

Lupus characteristically causes leukopenia (low white blood cell count), not leukocytosis:

• Severe leukopenia and lymphopenia are well-recognized hematologic complications of SLE and have been associated with increased risk of infections 1.
• Severe neutropenia (<500 cells/mm³) and severe lymphopenia (<500 cells/mm³) require continuous monitoring due to infection risk 1.
• In the majority of cases, leukopenia and neutropenia require no specific treatment 2.

Critical Exception: Adult-Onset Still's Disease (AOSD)

The evidence provided includes data on AOSD, which can mimic lupus but is a distinct entity:

• AOSD causes marked leukocytosis with striking neutrophilia, with 50% of patients having peripheral leukocyte counts >15×10⁹ cells/L and 37% having WBC counts >20×10⁹ cells/L 1.
• This leukocytosis results from bone marrow granulocyte hyperplasia and accompanies increased disease activity 1.
• This is NOT a feature of SLE—if a patient with presumed lupus has leukocytosis, reconsider the diagnosis or look for complications.

Red Blood Cell Abnormalities in Lupus

Lupus causes anemia (low red blood cell count), not elevated RBC counts:

• Anemia is the most common hematologic manifestation of SLE 3, 2.
• Multiple mechanisms cause anemia in lupus: chronic disease, autoimmune hemolytic anemia, renal insufficiency, blood loss, drug-induced effects, and rarely red cell aplasia or aplastic anemia 2.
• Severe anemia has been variably associated with organ involvement, disease progression, and worse prognosis 1, 4.
• Lower RBC counts are linked to renal and hematopoietic system impairments 5.
• RBC count is a key parameter in disease activity prediction models (AUC = 0.908) 5.

Clinical Approach When Elevated Counts Are Found

If you encounter a patient with lupus and elevated white or red blood cell counts:

1. Rule out infection first: Severe elevation of CRP (>50 mg/L) with leukocytosis suggests superimposed infection rather than lupus activity 1.

2. Review medications: Consider drug effects, particularly corticosteroids which can cause leukocytosis.

3. Assess for complications:

   • Reactive thrombocytosis is common in active lupus 1, but leukocytosis is not.
   • Consider thrombotic microangiopathy or other vascular complications if seeing unusual blood count patterns 4.

4. Reconsider the diagnosis: Elevated counts, especially marked leukocytosis, should prompt consideration of alternative diagnoses or overlapping conditions.

Monitoring Recommendations

Regular complete blood count monitoring is essential 4:

• Patients with inactive disease should be assessed every 6-12 months 1.
• High-risk patients (males, juvenile-onset SLE, serologically active) require monitoring at least every 3 months 4.
• Monitor for severe cytopenias: neutropenia <500 cells/mm³, lymphopenia <500 cells/mm³ 1.