Gout - Causes

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Location of Tophi. Tophi generally form in the following locations:

• Curved ridge along the edge of the outer ear
• Forearms
• Elbow or knee
• Hands or feet -- older patients, particularly women, are more likely to have gout in the small joints of the fingers.
• Around the heart and spine (rare)

Tophi are generally painless. However, they can cause pain and stiffness in the affected joint. Eventually, they can also erode cartilage and bone, ultimately destroying the joint. Large tophi under the skin of the hands and feet can give rise to extreme deformities.

Complications

Uric Acid Nephrolithiasis (Kidney Stones). Persons who have kidney stones that formed from uric acid are more likely to have higher levels of uric acid in their blood than in their urine. This suggests that gout is responsible for this type of kidney stones. Uric acid stones and other forms of kidney stones are present in 10 - 25% of patients with primary gout, a rate of more than 1,000 times that of the general population. In gout caused by other conditions (called secondary gout), the reported rate reaches 42%.

Click the icon to see an image of nephrolithiasis.

Not all of the kidney stones in patients with gout are made of uric acid. Some are made from calcium oxalate, calcium phosphate, or substances combined with uric acid. Uric acid stones can also form when you do not have gout or hyperuricemia.

Chronic Uric Acid Interstitial Nephropathy. Chronic uric acid interstitial nephropathy occurs when crystals slowly form in the structures and tubes that carry fluid from the kidney. It is reversible and not likely to injure the kidneys.

Kidney Failure. Sudden overproduction of uric acid can occasionally block the kidneys and cause them to fail. This occurrence is very uncommon but can develop after any of the following:

• Chemotherapy for leukemia or lymphoma, particularly acute forms of the disease
• Other cancers, such as breast cancer and lung cancer
• Epileptic seizures
• Pregnancy related preeclampsia or eclampsia
• Use of medications to prevent kidney transplant rejection, such as cyclosporine

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).