<s>[INST] <<SYS>> This is a medical question of type : exams and tests <</SYS>> How to diagnose Gout ? [/INST] To confirm a diagnosis of gout, the doctor inserts a needle into the inflamed joint and draws a sample of synovial fluid, the substance that lubricates a joint. A laboratory technician places some of the fluid on a slide and looks for uric acid crystals under a microscope. If uric acid crystals are found in the fluid surrounding the joint, the person usually has gout. </s>