Which Tests Are Used to Diagnose Psoriatic Arthritis?

Medically reviewed by Natalie Butler, RD, LD on March 16, 2017Written by Natalie Silver on March 16, 2017

Overview

There isn’t one single test that diagnoses psoriatic arthritis (PsA). Still, your doctor can perform a variety of tests to determine your condition and also rule out other joint-related, inflammatory conditions.

Your doctor will first ask about your medical history and perform a physical exam. During your physical exam, your doctor will look for:

  • swollen joints
  • patterns of pain or tenderness
  • pitting or rash on your skin and nails

Other diagnostic tests may include imaging tests, lab tests, and other evaluations. Your doctor may conduct tests to rule out conditions that have similar symptoms to PsA, such as:

Imaging tests

Imaging tests allow your doctor to examine your joints and bones closely. Imaging tests used to diagnose PsA include:

Your doctor may notice certain changes to your body that are specific to PsA through an X-ray. A MRI may allow your doctor to look at other parts of your body, such as tendons and other tissues, that may show signs of PsA.

Your doctor will give you specific instructions before your imaging tests. This information will help you come to your appointment prepared. You will undergo these tests at your doctor’s office or another medical center.

Blood and other lab tests

Laboratory tests are also useful for diagnosing PsA. Your doctor can look for certain clues from these tests to determine your condition. Generally, lab tests will be conducted at your doctor’s office or another medical center. These tests include:

Skin test: Your doctor may take a biopsy of your skin to diagnosis psoriasis.

Fluid test: Your doctor can take fluid from a joint with suspected PsA to determine your condition.

Blood test: Most blood tests will not diagnose PsA, but they may point to a different condition. Your doctor may look for certain factors in the blood, such as the rheumatoid factor. This factor indicates rheumatoid arthritis. If it’s present in your blood, you do not have PsA.

Your doctor may also look for signs of inflammation in your blood. People with PsA often have normal levels, though. Your doctor may also look for a genetic marker related to PsA, but finding it doesn’t necessarily diagnose the condition.

Other tests for psoriatic arthritis

Researchers in a 2014 study concluded that three screening tools can help doctors determine whether you may have PsA. These included the Psoriasis and Arthritis Screening Questionnaire (PASQ), Psoriasis Epidemiology Screening Tool (PEST), and Toronto Arthritis Screen (ToPAS).

These screenings require you to complete a questionnaire. Based on your answers, your doctor will determine if you need further care.

Your doctor may refer you to a rheumatologist if they can’t make a diagnosis. A rheumatologist is a doctor who specializes in musculoskeletal conditions such as psoriatic arthritis.

When to seek a diagnosis

Aches and pains in your joints may be a sign of psoriatic arthritis (PsA). This is a chronic inflammatory condition that benefits from early diagnosis and treatment. You should see your doctor if you have symptoms of PsA. There are no specific tests to confirm PsA, but your doctor can use several diagnostic methods to determine your condition.

Symptoms of PsA include:

  • pain and inflammation in the joints
  • tiredness
  • swollen fingers and toes
  • stiffness and tiredness, particularly in the morning
  • mood swings
  • changes to the nails
  • eye irritation, such as redness or pain
  • limited motion in the joints

PsA may be experienced in the:

  • hands
  • wrists
  • elbows
  • neck
  • lower back
  • knees
  • ankles
  • feet
  • places where tendons meet joints, like the spine, pelvis, ribs, Achilles heel, and bottoms of the feet

Who develops psoriatic arthritis?

You may experience PsA after you develop psoriasis. About 30 percent of people with psoriasis go on to develop PsA. And it’s estimated that 85 percent of people with PsA developed psoriasis first.

Keep in mind that while the two conditions are linked, your experience with each can be quite different. For example, you may have limited psoriasis symptoms but severe PsA.

Psoriasis and PsA are both autoimmune conditions. It isn’t known what specifically leads to psoriasis or PsA. One factor could be genetics. About 40 percent of people with these conditions have a family member with the same condition.

Other risk factors include certain age and infections that trigger the immune system. Most people diagnosed with the condition are in their 30s or 40s.

Treatment options for psoriatic arthritis

You may be diagnosed with PsA after testing. Then, your doctor will determine a treatment plan for your level of PsA based on your test results, symptoms, and overall physical health.

Your treatment plan may include one or more of the following:

  • nonsteroidal anti-inflammatory drugs
  • disease-modifying antirheumatic drugs
  • biologics
  • newly developed oral treatments
  • complementary alternative therapies
  • steroids injected in the joints
  • surgery to replace joints
  • physical or occupational therapy

Learn more: Treatment options for psoriatic arthritis »

You may also consider lifestyle changes to help ease symptoms of PsA. Try the following tips:

Easing PsA symptoms

  • Practice healthy eating habits, such as a Mediterranean or gluten-free diet.
  • Exercise regularly to help lose weight or maintain a healthy weight. Extra weight is inflammatory to the body and can put unnecessary pressure on your joints.
  • Get adequate rest.
  • Avoid engaging in strenuous activities that can put pressure on your joints, such as high-impact sports.

Learn more: Natural remedies for psoriatic arthritis »

Outlook

PsA is chronic and will not go away on its own, so you need to seek treatment for it. The longer you wait to diagnose and treat PsA, the more damage it can do to your joints. See your doctor regularly to discuss your PsA. They can help alleviate symptoms and prevent the condition from getting worse. You can help improve your condition by reducing your calorie intake, increasing your physical activity, and eating more fruits, vegetables, and healthy fats.

Additionally, PsA is linked to other conditions that are influenced by inflammation, such as:

  • obesity
  • diabetes
  • cardiovascular disease

Treatment for PsA can lower your risk of these related conditions, as well.

Be sure to contact your doctor if your existing symptoms worsen or if you develop new symptoms.

Keep reading: Why managing your pain isn’t the same thing as managing your disease »

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