What Is Psoriatic Arthritis?
Psoriatic arthritis is a type of arthritis that develops in people who have psoriasis. Psoriasis is a skin condition that causes patches of red, dry skin. Psoriatic arthritis can begin suddenly or develop over time. Symptoms include fatigue, joint swelling and tenderness, and reduced range of motion. Sometimes fingernails appear to be infected. Psoriatic arthritis can also develop after a joint injury and can lead to bursitis or tendonitis.
Why You Need a Rheumatologist
There’s no single test for psoriatic arthritis. It may take time to reach a diagnosis. If you have notable symptoms, your doctor or dermatologist may refer you to a rheumatologist. A rheumatologist is a doctor who specializes in diagnosing and treating arthritis. The rheumatologist will conduct a physical exam. Be prepared to list all your symptoms and give a complete medical history. Tell your doctor if you’ve been diagnosed with psoriasis. Symptoms, including joint swelling and fatigue, can mimic other conditions. Your doctor may perform tests to rule out gout, rheumatoid arthritis (RA), and reactive arthritis.
People with arthritis can experience periods of increased disease activity called flare-ups. Symptoms of a flare-up include muscle and joint pain and swelling. You may also have tendonitis and bursitis. In psoriatic arthritis, fingers and toes may swell up (dactylitis). Pain and swelling in your wrists, knees, ankles, or lower back is also possible. Repeated flare-ups can help your doctor make a psoriatic arthritis diagnosis.
According to The National Psoriasis Foundation, the skin disease comes before the joint disease in 85 percent of patients. If you have psoriasis and develop joint aches, pains, or swelling, consult with your doctor. The mildness or severity of your psoriasis doesn’t necessarily relate to the level of severity of the arthritis. If you have active psoriasis at the same time you have inflamed joints, your doctor will likely be able to make the diagnosis of psoriatic arthritis.
Psoriatic arthritis cannot be diagnosed with a blood test. But because symptoms are similar to those of RA, your doctor will probably order a blood test to rule out RA. The test will determine if your blood is positive for rheumatoid factor (RF), an antibody found in the blood of people with RA. Blood tests can also help rule out gout and osteoarthritis. If you have psoriatic arthritis, your blood work may show high levels of inflammation or mild anemia.
X-rays are not always useful in diagnosing early stage psoriatic arthritis. But as the disease progresses, your doctor may use imaging tests to see changes in the joints that are characteristic of this type of arthritis. Magnetic resonance imaging (MRI) alone can’t diagnose psoriatic arthritis, but it may help detect problems with your tendons and ligaments. CT scans and ultrasound can also be useful in determining progression or changes.
Joint Fluid Tests
People with psoriatic arthritis can be misdiagnosed with gout, a form of arthritis caused by too much uric acid in the body. Gout usually affects the big toes. Your doctor can take fluid from an affected joint to determine if it contains uric acid crystals. Depending on the results, your doctor can also rule out, or diagnose, gout through this test. It’s possible to have gout, psoriasis, and psoriatic arthritis at the same time.
Other Signs of Psoriatic Arthritis
Diagnosing psoriatic arthritis can be like solving a mystery. Additional signs include an elevated sedimentation rate, which indicates some amount of inflammation. An elevated C-reactive protein means there is acute inflammation. Some people with psoriatic arthritis also have mild anemia. None of these signs and symptoms alone can confirm psoriatic arthritis. Your doctor must examine all the evidence to confirm the diagnosis.