Psoriatic arthritis tests and diagnosis
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 skin and joint symptoms and your overall well-being. When evaluating PsA, some doctors may use an index called MDA (Minimal Disease Activity) to assess symptoms. This index is a tool for PsA specialists like rheumatologists and dermatologists to gauge how the disease is affecting you across several key measurements, including joint pain and swelling, skin symptoms, ability to do daily tasks, and more.
Psoriatic arthritis can damage joints over time if not controlled, so the earlier you receive a diagnosis and appropriate treatment, the better. If you’re currently seeing a dermatologist for psoriasis, and you are experiencing joint pain, tell your doctor. They may refer you to a rheumatologist. If any of these symptoms seem familiar, talk to your doctor.
What to expect when getting diagnosed with PsA
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:
- Which joints hurt?
Common affected joints include:
- Joints at the ends of fingers and toes
- When is your joint pain most severe?
People with psoriatic arthritis typically experience the most joint pain and stiffness when they wake up in the morning or after a prolonged period of sitting.
- 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.
During a physical exam, your doctor will look for several symptoms that are commonly associated with 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 are used to look for joint damage that may indicate arthritis
Watch This 15-Second Video – Then Take the PsA Symptom Quiz
Find out if your skin and joint symptoms could have something in common: psoriatic arthritis.
Sources: 1. C-reactive protein (CRP) Test. MedlinePlus. Accessed August 10, 2020. https://medlineplus.gov/lab-tests/c-reactive-protein-crp-test/. 2. Erythrocyte sedimentation rate (ESR). MedlinePlus. Accessed August 10, 2020. https://medlineplus.gov/lab-tests/erythrocyte-sedimentation-rate-esr/. 3. Gottlieb A, Merola JF. Psoriatic arthritis for dermatologists. J Dermatolog Treat. 2019;1-18. doi: 10.1080/09546634.2019.1605142. 4. Psoriatic arthritis. American College of Rheumatology. Updated March 2019. Accessed August 10, 2020. https://www.rheumatology.org/I-Am-A/Patient-Caregiver/Diseases-Conditions/Psoriatic-Arthritis. 5. Psoriatic arthritis. Arthritis Foundation. Accessed August 10, 2020. https://www.arthritis.org/diseases/psoriatic-arthritis.