Is it gout, or is it psoriatic arthritis?
If you have psoriasis and develop joint pain, your doctor should consider gout, as well as psoriatic arthritis. Not only can the symptoms of gout and psoriatic arthritis be similar, but having psoriasis and/or psoriatic arthritis raises your risk of developing gout, according to a recent study.
"When a patient presents with symptoms of joint disease, sometimes it's easy to tell which it is, and sometimes it's not," said Dr. Joseph Merola, co-director of the Center for Skin and Related Musculoskeletal Diseases at Brigham and Women's Hospital in Boston and a member of the National Psoriasis Foundation Medical Board.
Differences in symptoms, diagnosis
Dr. Doug Lienesch, a rheumatologist at the University of Pittsburgh Medical Center, said that gout usually presents in a single joint that goes from being normal to very inflamed in just a few hours. While the big toe is the most likely area to become inflamed, gout also can occur in feet, ankles, knees, hands and wrists, which can complicate the diagnosis.
Gout results from uric acid, which is produced both when your body's cells break down and from the foods you eat. The kidneys filter uric acid, which leaves the body when you urinate. Gout occurs when high levels of uric acid form crystals in the joints. The pain is likely to be severe the first day or two before gradually subsiding, but there can be lingering discomfort for several days to a few weeks. And over time, you may suffer more frequent attacks that last longer and affect more joints, Lienesch said.
Likewise, psoriatic arthritis can affect many joints, causing them to become painful, stiff and swollen. It can attack hand and foot joints that are closest to the nail, as well as the lower back, wrists, knees and ankles, and can also affect tendons, leading to tendonitis, Merola said.
There is no medical test to diagnose psoriatic arthritis.
"Psoriatic arthritis may show on X-rays, but it may not, especially if it's early in the course of the disease," Lienesch said.
However, there are tests that can help diagnose gout; your doctor can draw fluid from the affected joint to determine whether it contains uric acid crystals. A blood test also can confirm high levels of uric acid in your blood, but this test can be misleading, especially if you're in the throes of a flare, Merola said.
"Ultimately, it comes down to a clinical diagnosis by the rheumatologist," he said.
Increased risk of gout
In March, Merola and colleagues published a study in the British Medical Journal that found nearly double the risk for gout among those with self-reported psoriasis and nearly a five-fold increase in risk for those reporting psoriatic arthritis and psoriasis. The risk was greater for men than for women.
Researchers aren't sure why the conditions co-exist. Merola said one possible theory is that in people with psoriasis, skin cells turn over rapidly, and the uric acid that causes gout is a byproduct of cell turnover. In addition, an earlier study from Japan suggests that injured skin cells release uric acid crystals, which cause inflammation.
Whatever the cause of the pain and swelling, it is important to get the correct diagnosis so you can be treated appropriately. Some treatments overlap, but there are differences in treatment between gout and psoriatic arthritis, Merola said. For both, you may be given nonsteroidal anti-inflammatory drugs (NSAIDs) to control inflammation and pain. For gout, your doctor may recommend steroids.
"However, we try to avoid giving steroids to people with psoriasis because they can cause your skin to flare," Merola said.
Other drugs used to treat gout include medications that improve your kidneys' ability to remove uric acid from your body. PsA is also treated with disease-modifying anti-rheumatic drugs (DMARDS) such as sulfasalazine or methotrexate to stop joint damage and the progression of the disease. If those medications are unsuccessful, your doctor may prescribe biologics by injection or IV infusion. Recently, the FDA approved a new oral drug, apremalist, for PsA that selectively targets molecules inside immune cells.
Symptoms of gout
- There is a joint that goes from normal to red and inflamed in a few hours.
- Typically starts with the big toe.
- Intense pain can occur in feet, ankles, knees, hands and wrists.
- Over time, attacks may be more frequent and affect more joints.
Treatment of gout
- Nonsteroidal anti-inflammatory drugs (NSAIDs)
Symptoms of PsA
- Fingers and toes are stiff and painful, digits look like sausages.
- Joints of the hand closest to the nail are affected.
- Lower back, wrists, knees and ankles can be stiff and painful.
- Tendons, especially where they insert into bone, can be inflamed and tender.
Treatment of PsA
- Nonsteroidal anti-inflammatory drugs (NSAIDs)
- Disease-modifying anti-rheumatic drugs (DMARDS) such as methotrexate.
- Biologic drugs or biologics to stop joint damage, given by infusion or injection.
- New oral treatment Otezla (apremilast), which targets molecules inside immune cells.
- Alternative therapies including acupressure, acupuncture, massage and Reiki.
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