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Psoriatic arthritis tests and diagnosis

If you think you have psoriatic arthritis, it is important to see a doctor as soon as possible. Psoriatic arthritis can damage joints if not controlled, so the earlier you receive a diagnosis and appropriate treatment, the better.

The diagnosis of psoriatic arthritis is largely based on your medical history and a physical exam, and laboratory tests may be used to rule out other conditions. During an appointment, your doctor will likely ask you questions about specific joint symptoms and your overall well-being.

Medical history

At your doctor appointment, be prepared to answer questions regarding your medical history as accurately as possible. Some of the questions your doctor may ask you will likely include the following:

Joint pains

Which joints hurt?

Common affected joints include:

  • Wrists
  • Ankles
  • Knees
  • Joints at the end of fingers and toes
Severe pain

When is your pain most severe?

People with psoriatic arthritis typically experience the most joint pain and stiffness when they wake up in the morning.

Psoriasis in family

Does anyone in your family have psoriasis?

About 40% of people who have psoriatic arthritis have a family member with psoriatic arthritis, psoriasis, or arthritis, which suggests that a genetic component is a factor in who gets psoriatic arthritis.

It is important to note that psoriatic arthritis can occur in people without psoriasis on the skin, especially in people who have family members with psoriasis or psoriatic arthritis. It's also important to know that psoriatic arthritis can sometimes be misdiagnosed as rheumatoid arthritis, osteoarthritis, or gout.

Physical exam

During a physical exam, your doctor will look for several symptoms that are typical to psoriatic arthritis:

  • Tender, painful, or swollen joints
  • Pain in your feet, ankles, and lower back
  • An indication of psoriasis
  • Separation of the nail from the nail bed; pitting of the fingernails and toenails
  • Dactylitis (swollen fingers and toes)
  • Enthesitis (a condition in which ligaments and tendons become tender where they join onto bones, resulting in pain in the heel, in the sole of the foot, and in areas such as the elbows)

Laboratory tests and imaging procedures

Your doctor may order tests and procedures to help rule out other diseases or confirm your diagnosis. Some of these tests may include:

  • Signs of inflammation
    • Erythrocyte sedimentation rate: Measures how fast red blood cells form sedimentation in a test tube; elevated rate indicates inflammation
    • C-reactive protein: A measure of inflammation
  • X-rays: May show changes in the bone and cartilage that may indicate arthritis

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