American Board of Internal Medicine (ABIM) Certification Practice Exam

Which clinical finding would indicate chronic gout in synovial fluid analysis?

1. Presence of neutrophils

2. Extracellular crystals

3. Leukocyte count >100,000 cells/mL

4. Inflammatory cytokines

The correct answer is: Extracellular crystals

The presence of extracellular crystals in synovial fluid is a key indicator of chronic gout and points towards the diagnosis of this condition. In chronic gout, the joint fluid may exhibit monosodium urate crystals that can be visualized under polarized light microscopy. These needle-shaped or rod-like crystals are characteristic of gout and form due to hyperuricemia, which leads to the deposition of urate crystals in the joints. In contrast, other findings such as the presence of neutrophils or a leukocyte count greater than 100,000 cells/mL are typically associated with acute inflammatory responses, where neutrophil infiltration is common. While inflammation can occur in gout, especially during acute attacks, the chronic phase is more commonly associated with the presence of these specific crystals rather than solely inflammatory cells or cytokines. Inflammatory cytokines may be present as a consequence of the ongoing inflammatory process, but the definitive finding indicating chronic gout remains the extracellular crystals.