An accurate and early diagnosis of psoriatic arthritis will help you avoid the damage and deformity it can cause.
Your doctor will make a decision based on:
A physical exam
Your medical history and your family's
No single thing will diagnose psoriatic arthritis, but blood tests, imaging, and other tests can help your doctor. He may want to give you certain tests that check for rheumatoid arthritis, because it can look a lot like psoriatic arthritis.
Along with your symptoms, the most telling signs are the skin and nail changes you get with psoriasis, or specific changes in your X-rays.
Tenderness, pain, or swelling where tendons and ligaments attach to bones
Swollen fingers or toes
Patches of red, itchy skin
Thick silver or gray scaly areas on your skin
Changes or problems with your fingernails or toenails
Redness and swelling in your eye
Both psoriasis and psoriatic arthritis are related to your genes, so if you have a close family member with these skin or joint problems, you're more likely to have them, too.
Erythrocyte sedimentation rate (sed rate or ESR) gives a rough idea of how much inflammation is in your body, which could be caused by psoriatic arthritis. But higher levels can come from other autoimmune diseases, an infection, a tumor, liver disease, or pregnancy, too.
Rheumatoid factor (RF) and anti-CCP antibody tests can rule out rheumatoid arthritis. People with that condition may have higher levels of these in their blood.
More than half of people who have psoriatic arthritis with spine inflammation will have the genetic marker HLA-B27. You can get tested to find out if you do.
People with psoriatic arthritis may have mild anemia, or not enough healthy red blood cells.
These can show cartilage changes or bone injury that suggest arthritis in your spine and joints in your lower back and hands. Psoriatic arthritis usually looks different on X-rays than rheumatoid arthritis does.
Because psoriatic arthritis may lead to bone loss, your doctor may want to measure your bone strength. You could be at risk for osteoporosis and fractures.