A doctor will want to rule out other possible conditions that can cause symptoms similar to gout, such as septic arthritis and pseudogout. A patient exam and interview along with a lab test(s) can confirm or disprove a gout diagnosis:
Physical exam. A doctor will examine the patient's affected joint, noting swelling, pain points, and range of motion. The doctor will also look for the presence of white or yellowish bumps under the skin. These are collections of uric acid crystals (monosodium urate crystals) called tophi. Tophi are a strong indicator that a person suffers from chronic gout.
Patient interview. A doctor will ask a patient about family history and to describe the onset and pattern of his or her symptoms.
Joint fluid analysis. The most dependable way to diagnose gout is by examining the joint fluid under a microscope and looking for uric acid crystals. To obtain a joint fluid sample, a doctor will use a needle and syringe to draw a fluid from the affected joint. If uric acid crystals are found in the fluid sample, then gout is confirmed.
A small percentage of people have gout but do not have uric acid crystals in the joint fluid during analysis. For these people, additional tests must be done to rule out other possibilities, such as septic arthritis (infectious arthritis).
See Septic Bursitis
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Blood or urine test. A doctor may test a blood or urine sample for uric acid levels. Abnormally high uric acid levels, called hyperuricemia, indicate gout may be present. However, it is possible for the levels of uric acid in the blood to return to normal once a gout attack strikes, so absence of hyperuricemia does not completely rule out a diagnosis of gout.
Synovial biopsy. During a biopsy a doctor will arthroscopically remove a part of the membrane that encapsulates the affected joint, called the synovial membrane. The synovial membrane can be tested and examined for uric acid crystals and signs of gout.
X-rays. An X-ray of the joint may show the deposition of uric acid crystals. However, X-rays can be normal even when gout is present.
Most gout cases are diagnosed with a joint fluid analysis. An accurate diagnosis is important to long-term treatment and health.