Send joint fluid for fluid analysis, including:

  • Cell count and differential,
  • Gram stain,
  • Culture and sensitivity, and
  • Microscopic analysis for crystals. If crystals are found, their shape and appearance under polarized light are diagnostic.

In gout, crystals of monosodium urate (MSU) appear as needle-shaped intracellular and extracellular crystals. Negatively birefringent urate crystals are seen under a polarizing light.

In pseudogout, we see calcium pyrophosphate (CPP) crystals, which appear shorter than MSU crystals and are often rhomboidal.

Related Condition: Olecranon Bursitis.

https://emedicine.medscape.com/article/329958-workup

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