Having psoriasis makes you more likely to have certain other diseases. Find out about the connection.
Despite its very visible appearance on your skin, psoriasis is fundamentally an autoimmune condition, not a skin woe.
Autoimmune diseases share certain traits. With all autoimmune diseases, your body’s internal protection system misfires, and your body essentially begins attacking itself.
If you have psoriasis, you’re more likely to develop one or more other autoimmune diseases. A study published in November 2012 in the Journal of the American Academy of Dermatology concluded that people with psoriasis are nearly twice as likely as people without psoriasis to develop additional autoimmune diseases.
Of the 21 autoimmune diseases studied, 17 were found to be linked to psoriasis, including alopecia areata, celiac disease, scleroderma, lupus, and Sjogren’s syndrome. The autoimmune disease most strongly associated with psoriasis was rheumatoid arthritis (RA).
If you have psoriasis and psoriatic arthritis (PsA), your risk for an additional autoimmune disease increases even more. The study concluded that there may be a genetic or environmental cause that is shared across the spectrum of autoimmune diseases.
Psoriatic Arthritis or Rheumatoid Arthritis?
If you have psoriasis and consistently experience joint pains and aches, you should see your health care provider. PsA and RA are both very real possibilities for people with psoriasis.
Determining the type of arthritis you have can be challenging, but making the distinction is important, says Natalie E. Azar, MD, an assistant clinical professor of medicine and rheumatology at the New York University Langone Medical Center in New York City.
Although rheumatoid arthritis and psoriatic arthritis share many similar clinical features — for example, joint pain, stiffness, and swelling — it’s important to distinguish which condition you have in order to manage it well and know what to expect, Dr. Azar says.
In the last several years, Azar explains, physicians have come to understand more about PsA’s association with other health concerns already known to be linked to RA, such as uveitis, osteoporosis, metabolic syndrome, and increased cardiovascular risk, to name a few.
“Although treatment options can be strikingly similar,” Azar says, “significant advances have been made in the development and discovery of new biologic therapies very specific for PsA.”
Psoriatic arthritis occurs in as many as 30 percent of people who have psoriasis, but there is no single specific diagnostic test for the condition, says Azar. Your doctor may begin to suspect you have PsA if you’re experiencing changes to your skin and nails. Bring any such changes you notice to your doctor’s attention in case further testing is needed.
Your doctor may suspect rheumatoid arthritis from the presence of autoantibodies in your bloodstream known collectively as the rheumatoid factor. These antibodies are less typical in people with psoriatic arthritis.
Determining which kind of arthritis you have frequently depends on looking closely at how your joints are affected, Azar says. “RA involves the joints in a symmetrical fashion, and often, when rheumatoid factor is very high, there may be nodules under the skin. But PsA can present in a variety of different ways, from a large joint in asymmetric arthritis, to one, small finger joint of the hand.”
Another notable difference between the two diseases is the type of joint inflammation.
“RA is characterized by bone loss or erosion near the joint, while PsA is characterized by both erosion and new bone formation,” Azar says. RA affects mainly the joints, while PsA may also involve the entheses — the areas where muscles, ligaments, and tendons attach to the bone. People with PsA often experience recurrent bouts of tendinitis and plantar fasciitis. PsA can even involve the spine, resulting in spondylitis or sacroiliitis, painful conditions that tend to be absent in RA.
Signs and Symptoms to Watch For
There are more than 100 autoimmune diseases in all, and the list is growing, notes Amber L. Champion, MD, an endocrinologist who practices in North Platte, Nebraska.
“They are a diverse group of diseases and affect nearly every organ system of the body,” Dr. Champion says. She recommends talking with your doctor if you notice joint pain, patchy hair loss, skin tightening, frequent hives, or blood in your stool.
“Other symptoms might include unintended weight loss, abdominal pain, dry eyes and mouth, change in color inside the mouth, and headaches,” she adds. “Of course, these symptoms can be very nonspecific, so a thorough investigation is indicated if a symptom occurs.”