Gout is a form of inflammatory arthritis caused by the deposition of monosodium urate (MSU) crystals in joints and surrounding tissues, which occurs due to high levels of uric acid (hyperuricemia). Leukocytosis is an elevated white blood cell (WBC) count, a common response to inflammation or infection. An acute gout flare is a powerful inflammatory event that causes a measurable increase in the WBC count.
The Inflammatory Mechanism Linking Gout and Leukocytosis
An acute gout attack is a sterile inflammatory response, meaning it is not caused by infection. The process begins when monosodium urate crystals are deposited in the joint space. Resident immune cells, primarily macrophages, recognize these microparticles and attempt to engulf them (phagocytosis).
The crystals inside the macrophages trigger the activation of the specialized protein complex known as the NLRP3 inflammasome. This activation leads to the cleavage of an inactive precursor protein into its mature form, Interleukin-1 beta (IL-1ß). IL-1ß drives the pain, redness, and swelling characteristic of a gout flare.
IL-1ß and other signaling molecules (chemokines) travel through the bloodstream and act on local blood vessels. This causes vessel walls to express adhesion molecules, which recruit circulating white blood cells. These signals specifically recruit neutrophils, a type of WBC, to emigrate from the blood into the joint space. This systemic mobilization of neutrophils into the circulation causes the measured leukocytosis.
Interpreting White Blood Cell Counts During an Acute Gout Flare
During an acute gout flare, a complete blood count test often reveals a mild to moderate elevation in the total white blood cell count. In a typical acute flare, the systemic WBC count frequently ranges between 10,000 and 15,000 cells per cubic millimeter of blood. The extent of this WBC elevation generally correlates with the intensity and duration of the inflammatory attack. A significant elevation can occur from gout alone, without the presence of infection.
To interpret the cause of the leukocytosis, medical professionals rely on the differential count, which breaks down the total WBC count into specific cell types. Leukocytosis caused by gout is predominantly a neutrophilia, meaning the majority of the increase is due to the surge of neutrophils.
When an Elevated WBC Count Signals More Than Just Gout
While leukocytosis is expected in a gout flare, certain results and clinical signs raise suspicion for a more serious underlying condition. The most important diagnosis to exclude is septic arthritis, a bacterial infection within the joint space that requires immediate treatment.
A systemic WBC count significantly exceeding 15,000 to 20,000 cells/mm³ is often a red flag, suggesting a possible co-existing infection. Clinically, high fever, shaking chills, or severe sickness disproportionate to the joint pain also suggest an infectious cause. Elevated inflammatory markers, such as C-reactive protein (CRP), are not solely diagnostic since they are also high in gout.
The most definitive way to distinguish between sterile gout and septic arthritis is through joint aspiration, where fluid is drawn for analysis. If the WBC count in the joint fluid is over 50,000 cells/µL, it is highly suspicious for septic arthritis. However, gout alone can occasionally produce synovial fluid counts that are just as high, making crystal identification and bacterial culture necessary for an accurate diagnosis.