A procedure called arthrocentesis is performed. The health care provider uses a needle attached to a syringe to draw out fluid from the affected joint. This is called aspiration. Local anesthesia is not used because it can reduce the effectiveness of the procedure. However, the procedure is usually only mildly uncomfortable. Afterwards, there can be some minor discomfort in the area where the needle was inserted, but it usually goes away quickly.
The fluid sample is sent to a laboratory for analysis. Testing can reveal the presence of monosodium urate (MSU) crystals, which will nearly always confirm a diagnosis of gout. The laboratory can also test the sample for infection.
The procedure itself can cause infection, though this occurs in less than 0.1% of patients. Aspiration sometimes eases the patient's symptoms by reducing swelling and pressure on the tissue surrounding the joint.
Urine Tests
It is sometimes helpful to gauge the amount of uric acid found in a patient's urine, particularly if the patient is young and has pronounced hyperuricemia that might be related to a metabolic disorder. If uric acid in the urine exceeds a particular value, further tests for an enzyme defect or other identifiable cause of gout should be performed. Greater-than-normal amounts of uric acid in the urine also mean that the patient is more likely to develop uric acid kidney stones.
Typically, a 24-hour urine test is performed. The patient discards the first urination sample on the day of the test. Afterward all urine passed over the next 24 hours is collected into a special container, including the first urination on the morning of day two. The container is delivered to the patient's health care provider or sent directly to the laboratory.
The urine is collected between attacks, after the patient has been placed on a purine-reduced diet. The patient is also asked to temporarily stop using alcohol and any medications that can interfere with the test. The patient should not change any of his or her usual eating or drinking patterns when performing this test.
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Review Date: 01/04/2011
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine,
Harvard Medical School; Physician, Massachusetts General Hospital.
Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M.,
Inc.
A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)
