Synovial Fluid for Crystals
This test analyzes synovial fluid, the lubricating fluid found in joints, to detect the presence of crystals. The most common types of crystals tested for are uric acid crystals (which can indicate gout) and calcium pyrophosphate dihydrate (CPPD) crystals (which are associated with pseudogout). The presence of these crystals in the synovial fluid helps in diagnosing certain types of arthritis, especially inflammatory conditions like gout and pseudogout. The test is performed by aspirating fluid from an affected joint, typically using a needle, and examining it under a microscope.