Does Prednisone Increase RDW?
Yes, prednisone use is associated with increased RDW values in patients with systemic lupus erythematosus and other inflammatory conditions, though this relationship appears to reflect underlying disease activity and inflammation rather than a direct drug effect. 1
Evidence for Prednisone-RDW Association
The most direct evidence comes from a 2024 study in systemic lupus erythematosus (SLE) patients, where prednisone use was significantly associated with higher RDW levels after multivariable adjustment for confounding factors. 1 This study analyzed 284 SLE patients and found that several disease characteristics, including prednisone and azathioprine use, correlated with elevated RDW values. 1
Mechanistic Understanding
The relationship between prednisone and RDW elevation likely operates through several interconnected pathways:
Chronic inflammation and oxidative stress are primary drivers of RDW elevation, causing impaired erythropoiesis, shortened red blood cell lifespan, and erythrocyte membrane damage. 2, 3
Prednisone use typically indicates more severe underlying disease activity, which itself drives RDW elevation through inflammatory cytokines and metabolic derangements. 1
The association between cumulative disease damage, disease activity scores, and higher RDW values suggests that prednisone may be a marker of disease severity rather than the direct cause of RDW elevation. 1
Clinical Context and Interpretation
When evaluating elevated RDW in patients on prednisone:
Consider the underlying inflammatory condition as the primary driver of RDW changes, not the corticosteroid itself. 1, 3
RDW serves as a surrogate biomarker for disease activity and cumulative organ damage in inflammatory conditions like SLE. 1
Elevated RDW reflects profound deregulation of erythrocyte homeostasis involving impaired erythropoiesis, abnormal red blood cell survival, shortening of telomere length, oxidative stress, inflammation, and poor nutritional status. 3
Important Caveats
The evidence does not establish prednisone as an independent cause of RDW elevation—rather, prednisone use correlates with conditions that inherently elevate RDW. 1
Patients on prednisone often have multiple confounding factors (active inflammation, nutritional deficiencies, chronic disease) that independently affect RDW. 2, 3
Do not attribute elevated RDW solely to prednisone without investigating other causes, particularly iron deficiency (RDW >14.0% with low MCV), vitamin deficiencies, hemolysis, or the underlying inflammatory disease itself. 4, 2