Can Rheumatoid Arthritis (RA) cause leukocytosis, an increase in White Blood Cells (WBC)?

From the Guidelines

Rheumatoid arthritis can indeed cause an increase in white blood cell (WBC) counts due to the body's inflammatory response to the autoimmune process. During active flares of rheumatoid arthritis, the immune system's heightened activity leads to the production and release of more white blood cells into the bloodstream, typically involving neutrophils, which are the most common type of white blood cells involved in acute inflammation 1. This elevation in WBC count is a reflection of the immune system's response to the inflammation occurring in the joints and potentially other tissues. However, it's crucial to note that not all rheumatoid arthritis patients will exhibit elevated WBC counts, and when present, the elevation is usually mild to moderate.

Other causes of increased WBC counts, such as infections, should still be considered, especially in rheumatoid arthritis patients taking immunosuppressive medications like methotrexate, biologics, or corticosteroids, as they may be more susceptible to infections 1. Regular monitoring of blood counts is an essential part of rheumatoid arthritis management to track disease activity and medication effects, as outlined in the 2015 American College of Rheumatology guideline for the treatment of rheumatoid arthritis 1. The guideline recommends optimal follow-up laboratory monitoring intervals for complete blood count, liver transaminase levels, and serum creatinine levels for patients with rheumatoid arthritis receiving disease-modifying antirheumatic drugs.

Key points to consider in the management of rheumatoid arthritis and its impact on WBC counts include:

• The importance of monitoring blood counts to track disease activity and medication effects
• The potential for immunosuppressive medications to increase the risk of infections
• The need to consider other causes of increased WBC counts, such as infections
• The role of regular monitoring in adjusting treatment strategies to minimize toxicity and maximize efficacy 1.

From the Research

Rheumatoid Arthritis and White Blood Cell Count

• Rheumatoid arthritis (RA) is a chronic, systemic autoimmune inflammatory arthritis that can cause various symptoms, including joint pain, stiffness, and swelling 2.
• The disease can lead to increased white blood cell (WBC) count, also known as leukocytosis, which is defined as two or more WBC counts greater than 10,000/mm 3.
• Leukocytosis in RA is often caused by an increase in neutrophils and is associated with more active arthritis, as well as the use of corticosteroids 3.
• Studies have shown that patients with RA who have leukocytosis tend to have more severe disease activity, but there is no significant difference in extra-articular manifestations or drug therapy, except for the use of corticosteroids 3.

Disease-Modifying Antirheumatic Drugs and WBC Count

• Disease-modifying antirheumatic drugs (DMARDs) are commonly used to treat RA and can affect WBC count 4, 5, 6.
• Methotrexate, a commonly used DMARD, has been shown to be effective in reducing disease activity and slowing joint damage in RA patients, but its effect on WBC count is not well established 2, 5, 6.
• Other DMARDs, such as sulfasalazine and leflunomide, may also affect WBC count, but more research is needed to fully understand their effects 5, 6.

Clinical Significance of Leukocytosis in RA

• Leukocytosis in RA can be a sign of active disease or infection, and patients with newly detected leukocytosis should be evaluated for occult infection 3.
• However, in the absence of suggestive signs and symptoms, an infectious cause is seldom found, and continuing vigilance is recommended 3.