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Diseases > Psoriatic Arthritis | PsA > Diagnosis | Psoriatic Arthritis | PsA

What is Psoriatic Arthritis (PsA)?

Psoriatic arthritis is one of 100 different types of arthritis. It is in a family of related conditions called spondyloarthropathies. Other members of this family include ankylosing spondylitis, reactive arthritis and arthritis associated with inflammatory bowel disease.

What causes PsA?

Psoriatic arthritis is a long-term (chronic) disease. It occurs when the body’s immune system begins to attack its own joints as well as the skin. The reason for this is not well understood. The attack causes inflammation of the joints. The word inflammation comes from the Latin word inflammare which means to light on fire. In people with PsA, inflammation causes the joints to become warm, swollen, painful, and sometimes red. In other words, the joints can feel like they’re “on fire.”

Psoriatic arthritis tends to run in families. In other words, it is thought that genetics plays a role in who gets PsA. People who have family members affected by PsA have a higher chance of having PsA themselves. Sometimes, a whole family can be affected by PsA.

Think of it like this. Psoriatic arthritis is like a fire burning in the joints and the skin. To make a fire you need wood and something to light it with. Let’s think of the wood like it’s your genes. You need the right type of wood (nice and dry) to light a fire. Researchers have found that you need the right type of genes to light the fire of PsA. But that’s not the end of the story. You also need something to light the fire with. We’re not entirely sure what lights the fire of PsA. It might be the chemicals from cigarette smoke or a virus in the environment. Several triggers might be needed to light the fire. We just don’t know and it’s like looking for a needle in a haystack.

Who gets PsA?

It is estimated that PsA affects between 1 and 2 people in every 1000. That means that in a town of 10,000 people, you could expect between 10 and 20 people to have PsA. You can see that it’s not all that uncommon: you might know someone else who has it. Some famous people who have or have had PsA include pro golfer Phil Mickelson, and guitarist Shawn Lane. Psoriatic arthritis is just as likely to affect men as it is to affect women.

In about 7 out of 10 people with PsA, the skin is affected before the joints. In the other 3 out of 10 people who develop PsA, the skin and joints may be affected at the same time or the skin is affected after the joints. To be diagnosed with PsA you don’t even need to have psoriasis. In fact, a first degree relative (mom, dad, brother, sister, or child) with psoriasis counts as well!

The signs and symptoms of PsA usually start in adults aged 30 to 50 years old. It affects between about 30% of people with psoriasis. In other words, people with psoriasis have a 1 in 3 chance of developing PsA. You can also look at it from the opposite perspective: someone with psoriasis has a 2 in 3 chance of never developing PsA.

How is PsA diagnosed?

Psoriatic arthritis is best diagnosed by a rheumatologist.  A rheumatologist is a specialist in arthritis and autoimmune diseases. The rheumatologist will take a complete history and perform a thorough physical examination.  This is usually followed by blood tests and x-rays.

What tests are done to diagnose PsA?

Blood tests can be done to help diagnose PsA. However, in some people these blood tests can be normal and yet the person might still have PsA. A blood test alone cannot diagnose PsA. Tests that can help make a diagnosis include:

  1. Complete Blood Count (CBC)
  2. Erythrocyte Sedimentation Rate (ESR)
  3. C-Reactive Protein (CRP)

X-rays of the joints can also be helpful in diagnosing psoriatic arthritis.

Read more – Symptoms of Psoriatic Arthritis