By Sara Gaynes Levy; Medically reviewed by Olga Petryna, M.D., FACR
Psoriatic arthritis is a lifelong inflammatory condition that can be challenging to manage, especially if you also have to manage psoriasis symptoms (another chronic condition that people with psoriatic arthritis commonly develop). In some cases, psoriatic arthritis can be debilitating and damage joints when it is left untreated. That’s why a prompt psoriatic arthritis diagnosis is important so you can get proper care and minimize the likelihood of this happening. Understanding more about the condition, including risk factors for psoriatic arthritis and psoriatic arthritis symptoms, can help you determine if you want to talk to your doctor about pursuing a psoriatic arthritis diagnosis and workup. Beyond that, the following information can help you better anticipate the process involved with a psoriatic arthritis diagnosis.
What is psoriatic arthritis?
Psoriatic arthritis is an autoimmune disorder, meaning the immune system misreads healthy joint, tendon, pelvic joints, or spine as a potential threat that needs to be attacked. This process can cause inflammation, pain, swelling, and/or stiffness, most commonly in the hands, feet, ankles, wrists, or knees. One of the major risk factors of developing psoriatic arthritis is having psoriasis, a skin condition most commonly characterized by patches of scaly skin that has dead skin cells on top. Of the approximately 7.5 million people in the U.S. who have psoriasis, between 20 and 30 percent will go on to develop psoriatic arthritis. That said, psoriasis does not cause psoriatic arthritis, and having the skin condition doesn’t mean you’ll automatically develop psoriatic arthritis.
Psoriatic arthritis usually shows up after about 7 to 10 years of living with psoriasis, although a small minority of patients will develop psoriatic arthritis before ever seeing any skin evidence of psoriasis. And the severity of someone’s psoriasis doesn’t determine whether they will develop psoriatic arthritis. “Someone can have a horrible skin disease, but no joint problems, and vice versa,” Samar Gupta, M.D., an associate professor at the University of Michigan Medical School and the chief of VA clinical rheumatology and medical education, tells SELF.
We don’t know why the two conditions are connected, but there are certain types of psoriasis more closely linked to psoriatic arthritis, Dr. Gupta explains. “If someone has, for example, scalp psoriasis, we find that it is more associated with psoriatic arthritis,” he says.
Other psoriatic arthritis risk factors include:
- Tissue damage related to injuries
- Severe infections
- Family history of psoriasis or psoriatic arthritis
Is psoriatic arthritis genetic?
There is no single gene that causes psoriatic arthritis to develop, but experts believe there is probably a genetic component, as nearly half of those who develop the condition have a family history of either psoriasis or psoriatic arthritis. A family of genes known as the human leukocyte antigen (HLA) complex may be involved. HLA genes help the immune system know which proteins to attack, and variations in this group of genes may alter your risk of getting psoriatic arthritis. However, there is still a lot of research to be done. Some people with psoriatic arthritis test positive for the HLA antigen, but a positive test is not a requirement for a psoriatic arthritis diagnosis.
Psoriatic arthritis symptoms
Psoriatic arthritis can be mild, moderate, or severe, depending on how intense the experiences of pain, swelling, tenderness, or stiffness are. Hallmark psoriatic arthritis symptoms commonly include:
Joint pain, aching, or tenderness (often in the feet, ankles, knees, wrists, or hands)
Depending on the location and the severity of the inflammation, these symptoms can change from person to person, and not everyone will experience all symptoms. (Symptoms can also flare up and go into remission intermittently. Trauma to the joints, such as from an injury, may cause flares.)
Psoriatic arthritis diagnosis
You’ll most likely be referred to a rheumatologist for an official psoriatic arthritis diagnosis, explains Dr. Gupta. (Although dermatologists sometimes diagnose psoriatic arthritis when they’ve already been treating someone for psoriasis.) “Most patients get referred to [rheumatology] when they start having joint pain, after having had psoriasis for years,” Dr. Gupta says.
Tests for psoriatic arthritis
Unfortunately, no single test exists for diagnosing psoriatic arthritis. Physicians may use a combination of tests, in conjunction with a person’s medical history and a physical exam, to assess whether someone has psoriatic arthritis.
Physical exam
During the exam, your doctor will examine your joints and tendons for tenderness and swelling, check your fingernails for pulling and pitting, and look for other uncomfortable areas. If you’ve never been diagnosed with psoriasis, your physician may also check your scalp as psoriasis can hide there without being terribly bothersome (not to mention this type of psoriasis is also commonly associated with psoriatic arthritis).
Medical history
Your rheumatologist will want to know if you have previously been diagnosed with psoriasis, as this can help distinguish psoriatic arthritis from other conditions. Your doctor will also ask about a family history of both psoriatic arthritis and psoriasis. This is helpful in the event that you don’t also have psoriasis since a family history of either condition makes it more likely that your symptoms are caused by psoriatic arthritis. About 40 percent of people who have psoriatic arthritis have at least one first-degree relative who also has it, so make sure you are aware whether any of your siblings or parents have been diagnosed with psoriasis or psoriatic arthritis.
Imaging tests for psoriatic arthritis
To further evaluate your condition, including learning how far along your psoriatic arthritis may be, your doctor needs to look for signs of inflammation or joint damage inside your body, which is done via imaging tests. X-rays are the most common initial imaging tests used to diagnose psoriatic arthritis. Magnetic resonance imaging (MRI) is sometimes used to assess your tendons and ligaments in the feet and is frequently used to assess for inflammation in the lower back where x-ray can be less informative.
X-rays
After your physical exam and medical history discussion, your doctor may order X-rays. “The [psoriatic arthritis] diagnosis basically comes from a good physical exam and X-rays,” Dr. Gupta says. The more advanced the psoriatic arthritis is, the more helpful an X-ray can be (there is not much to see early on in psoriatic arthritis.) On X-rays, doctors are looking for changes in the joints specific to psoriatic arthritis. One is described as “pencil-in-cup.” In pencil-in-cup, the end of a bone is reduced to a sharp point. “If psoriatic arthritis has advanced enough, we can see the bone damage in the joints which makes it look like a pencil in a cup,” says Dr. Gupta.
If there are no psoriatic arthritis findings present on the X-rays, your doctor can order additional tests to rule out other conditions, like rheumatoid arthritis and gout since both can cause joint pain and inflammation similarly to psoriatic arthritis. This is helpful in situations where people have less severe forms of psoriatic arthritis that aren’t easily detected on X-rays.
Lab tests
To rule out gout, your doctor can perform a joint fluid test. By using a needle to extract a small amount of fluid from a swollen, tender, or stiff joint, your doctor can look for the presence of uric acid crystals, which indicates that you may have gout.
Blood tests
Blood tests cannot positively identify psoriatic arthritis, but they can still be helpful for ruling out other types of inflammatory arthritis. Some blood tests can identify inflammation in the body, for example, one test looks for C-reactive protein, a blood marker of inflammation. The presence of C-reactive protein may help support a psoriatic arthritis diagnosis.
Rheumatoid factor
Nearly everyone who is evaluated for psoriatic arthritis will have their blood tested for rheumatoid factor (RF), a protein produced by the immune system that attacks healthy joints. People with rheumatoid arthritis will often test positive for the RF antibody. People with psoriatic arthritis generally test negative for the RF antibody. (It’s not a guarantee, though: about 20 percent of people who do have rheumatoid arthritis test negative for RF.) To test for RF, a health care worker will take a vial of blood using a small needle—you don’t have to do anything to prepare, and it usually only takes a few minutes.
Screening tests
Sometimes, physicians ask people to complete screening tests to assess the patient’s risk for developing psoriatic arthritis. For example, people with psoriasis may be asked to complete these tests, which are self-reported questionnaires covering topics like joint pain and morning stiffness. These can help physicians refer people to a rheumatologist for further psoriatic arthritis testing and possible diagnosis. Screening tests aren’t perfect— they’re most likely only moderately accurate—but they may help doctors identify early-stage disease, which is easier to treat.
Psoriatic arthritis diagnostic criteria
Finally, in order to confirm a psoriatic arthritis diagnosis, your doctor can use a criteria checklist. Since 2006, doctors have used a test designed by a group of rheumatologists known as the CASPAR—classification criteria of psoriatic arthritis— for this purpose. The CASPAR test assigns point values to different symptoms and signs, as follows:
- The presence of skin psoriasis (2 points, 1 point for having it previously or having a family history but not having it yourself)
- Nail lesions, pitting, or pulling away from the nail bed (1 point)
- Swollen toe or nail (1 point)
- RF negative (1 point)
- Juxta-articular bone formation (in other words, a bone formation near a joint) (1 point)
People who score at least three points are considered to have psoriatic arthritis.
Psoriatic arthritis treatment
Psoriatic arthritis treatment is highly variable, depending on the severity of your case, how many joints are affected by the condition, whether you have psoriasis, and your personal preferences. “The treatment is very individualized,” Dr. Gupta says. Treatment can both help ease the severity of symptoms and prevent the disease from getting worse. Usually, doctors will recommend medication combined with lifestyle treatment for the best symptom management.
Psoriatic arthritis medication
Psoriatic arthritis medication functions like a ladder: If the first treatment doesn’t combat your symptoms, you stop taking it and climb up to the next rung. People with mild cases of psoriatic arthritis might just treat symptoms as they occur. Then, if those don’t work, you may be prescribed a more powerful drug. Here are the commonly used psoriatic arthritis medications:
Nonsteroidal anti-inflammatory drugs (NSAIDs): These drugs treat symptoms by reducing inflammation and pain when it occurs. “If the disease is mild, we can sometimes get away with symptomatic treatment, like a prescription-strength Motrin,” Dr. Gupta says. NSAIDs can be both over-the-counter (aspirin, ibuprofen, naproxen) or prescription (celecoxib or prescription-strength Motrin). Side effects are generally mild and may include gas and an upset stomach.
Lifestyle therapy
Managing psoriatic arthritis often includes more than just taking medications. Your doctor may also recommend the following:
Exercise/physical therapy: This can help reduce stiffness and joint pain (and a lack of exercise can make joint instability worse). Range-of-motion exercises, strength training, and low-impact activities can help you better support and stabilize your joints. A physical therapist can help recommend specific exercises that work best for you and your abilities. They can also teach you proper body mechanics for everyday tasks like sitting, standing, and bending, in order to protect your joints. If possible, ask your physician for a referral to a PT.
Psoriatic arthritis is a lifelong condition, but getting an early psoriatic arthritis diagnosis can really help you avoid potential joint damage and pain. “We are lucky in this era,” Dr. Gupta says. “We have so many options that we can pick and choose the most appropriate treatment. And there are very, very effective therapies available.”
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