Gout, Uric Acid, and Lupus Nephritis

Sharp pains in the joints that seem to come and go at random. It sounds like lupus, but it could be a sign of gout.

The pain associated with gout has been documented for millennia. Galen, the celebrated Greco-Roman physician, described the condition in his medical writings and it even makes appearances in Roman literature. Gout is most common among older males — not the most common demographic of Lupus Warriors. However, people with lupus can get it, especially if they have kidney damage or lupus nephritis.

Gout is caused by a buildup of uric acid in the body. Usually, this substance gets filtered out by the kidneys. The built-up uric acid ends up crystallizing into sharp fragments in the joints. These crystal spikes cause pain, swelling, and inflammation. The most commonly affected joints are the:

• big toes
• ankles
• heels
• knees

3 Physical Mechanisms for Developing Gout

Diet

Gout has been historically blamed on a “rich diet,” or a diet rich in a substance called purines. Purines are a family of protein that, when broken down by the body, becomes uric acid. Purines are all over the place, even in our very DNA. But, the purines that contribute to gout are found in meat, seafood, and alcohol. The purines found in vegetables don’t appear to contribute to gout (which is great because caffeine is one of them!).

Kidney Damage

Kidney damage is also a known factor. Normally, kidneys filter out 70% of the uric acid from the bloodstream and flush it out in urine. The remaining uric acids leaves the body through the intestines as feces and the skin as sweat. When the kidneys aren’t working properly, uric acid builds up in the body.

Enzymes

In rare instances, there can be problems with the enzymes that the body uses to break down and clear out uric acid. Arthritis.org emphasizes this disorder, called hyperuremia, where the body produces too much uric acid and diet itself has little effect. 

When gout co-occurs with lupus or other autoimmune disease, the combination of kidney problems and diet is more likely the cause.

Linking to Lupus

Lupus nephritis, the form of lupus affecting the kidneys, is a risk factor for increased uric acid in the body. But, lupus can also increase the risk in other ways. The symptoms that go along with lupus, such as hypertension and cardiovascular disease, and medications, such as diuretics, can contribute to gout. 

The two conditions can also be part of an unfortunate cycle. Crystals trigger the body’s inflammatory response, leading to lupus flares; lupus flares can increase kidney damage making it harder for the body to clear uric acid. That is part of the reason why it is so important to detect and treat gout when it shows up with lupus.

Telling the Conditions Apart

The biggest issue with lupus and gout is that one can mask the other. If your doctor assumes that your joint pain is from lupus, the pain can get worse. On the other hand, if you have undiagnosed lupus and your doctor assumes gout, lupus can go untreated.

This association between the conditions has been known for decades. In a case study from 1988, the researchers concluded:

“Gout should be considered in the differential diagnosis of patients with SLE who present with acute arthritis and/or subcutaneous nodules particularly in those with longstanding stable nephritis who are receiving diuretics for concomitant hypertension.”

“Differential diagnosis” is the process clinicians use to distinguish one condition from another when there are similar features or symptoms.

Telling the difference between gout and lupus is tricky, but there are a few observable symptoms that help: 

• Lupus can impact joints throughout the body. It generally has less swelling and more variation in pain
• Gout will usually be in the feet and ankles, though it can spread to the hands. It causes swelling, redness, and intense pain.

Diagnosing Gout

If you have  swelling and redness, particularly in the feet, ankle, and especially in your big toe, your doctor may test for gout. Typically, this is a blood test for uric acid in the blood. A new test may also be able to diagnose it by looking at the microbiome. 

According to an article in Nature, two species of bacteria (Bacteroidies caccae and Bacteroides xylanisolvens) are more common in the guts of people with gout. The Microbial Index of Gout accurately diagnoses with 88.9% accuracy. Plus, microbiome tests are noninvasive as they only require a fecal sample. 

You can find out more about the microbiome and lupus here.

Treating Gout

The key to treating gout is to reduce the levels of uric acid in your bloodstream so that it doesn’t form crystals. While kidney damage and lupus nephritis can make treatment complicated, a strategic diet and various medications can help.   

Gout-friendly diets are low in meat and seafood and are high in plant-based foods. Fruits are important to this diet, since vitamin C, a well-known antioxidant, helps clear out crystals. If you need to go on a special diet, food planning and supplements can make sure that you are well-nourished. Be sure to talk to your lupus treatment team and consider adding a registered dietician to help.

Medications for gout include:

• allopurinol
  • A xanthine oxidase enzyme inhibitor reduces urate levels in the blood stream and stops the formation of crystals
  • Urate is a salt derived from uric acid
• NSAIDS (for pain and swelling)
• steroids and corticosteroids (including prednisone and colchicine
• anti-inflammatory drugs

Allopurinol shouldn’t be used during pregnancy. It is usually discontinued when urate levels are more manageable. Some doctors take a more direct approach and use vibrations to break down the urate crystals.

Looking to Learn More?

Check out these great health centers and organizations:

• Johns Hopkins Arthritis Center 
• Alliance for Gout Awareness 
• American College of Rheumatology 
• Arthritis Foundation 
• CDC