Thursday, July 18, 2024

What Blood Test For Psoriatic Arthritis

Tests To Diagnose Psoriatic Arthritis

Why are regular blood tests necessary for Psoriatic Arthritis?

Blood Tests

These tests can help confirm psoriatic arthritis and rule out other conditions, like rheumatoid arthritis.

  • Erythrocyte sedimentation rate : 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 and anti-CCP antibody: These tests can rule out rheumatoid arthritis. People with that condition may have higher levels of these in their blood.
  • HLA-B27: More than half of people who have psoriatic arthritis with spine inflammation will have this genetic marker. You can get tested to find out if you do.
  • Iron tests: People with psoriatic arthritis may have mild anemia, or not enough healthy red blood cells.


These can show cartilage changes or bone and joint damage that suggests arthritis in your spine, hands, or feet. Psoriatic arthritis usually looks different on X-rays than rheumatoid arthritis does.

Bone Density Scan

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.

Joint Fluid Test

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Assessing The Immune System

While biologic DMARDs can be very effective at slowing joint damage progression and treating the symptoms of PsA, they also suppress the immune system, which can increase the likelihood of infection.

If you are prescribed a biologic to treat your PsA, in addition to liver enzyme testing, your doctor will likely monitor you for tuberculosis and take frequent complete blood count panels to assess your risk of infection.

Depending on which biologic you are prescribed, additional monitoring may be required.8

Blood Tests For Psoriatic Arthritis

Diagnosing psoriatic arthritis can be a complicated process. In some cases, a doctor can make an initial diagnosis based on medical history and a physical exam. If a person already has the skin symptoms associated with psoriasis and begins experiencing joint pain, the odds that they have PsA are relatively high. But identifying psoriatic arthritis isnt always simple. And while PsA usually starts about a decade after psoriasis, it has been found to appear before the skin condition in about 15 percent of cases. When this occurs, doctors will need to run blood tests to rule out other types of arthritis and inflammatory conditions before making a psoriatic arthritis diagnosis.

Related: Blood and imaging tests for diagnosing psoriatic arthritis

When you attend your diagnostic appointment, your rheumatologist will likely draw some blood and conduct routine tests to make a PsA diagnosis. A few of the most common blood-based screenings are listed below.

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Who Is At Risk For Psoriatic Arthritis

Psoriasis affects 2-3 percent of the population or approximately 7 million people in the U.S. and up to 30% of these people can develop psoriatic arthritis. Psoriatic arthritis occurs most commonly in adults between the ages of 35 and 55 however, it can develop at any age. Psoriatic arthritis affects men and women equally.

It is possible to develop psoriatic arthritis with only a family history of psoriasis and while less common, psoriatic arthritis can occur before psoriasis appears. Children of parents with psoriasis are three times more likely to have psoriasis and are at greater risk for developing psoriatic arthritis. The most typical age of juvenile onset is 9-11 years of age.

Symptoms Of Psoriatic Arthritis

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The severity of the condition can vary considerably from person to person. Some people may have severe problems affecting many joints, whereas others may only notice mild symptoms in 1 or 2 joints.

There may be times when your symptoms improve and periods when they get worse .

Relapses can be very difficult to predict, but can often be managed with medicine when they do occur.

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When To Seek A Diagnosis

Aches and pains in your joints may be a sign of psoriatic arthritis . This is a chronic inflammatory condition that benefits from early diagnosis and treatment. You should see your doctor if you have symptoms of PsA. There are no specific tests to confirm PsA, but your doctor can use several diagnostic methods to determine your condition.

Symptoms of PsA include:

  • pain and inflammation in the joints
  • stiffness and tiredness, particularly in the morning

Psoriatic Arthritis Blood Test: Anemia

When you have psoriatic arthritis, ongoing inflammation may cause anemia, a decrease in healthy red blood cells that can lead to dizziness, shortness of breath, and exhaustion, says Cadet.

By measuring your blood levels of hemoglobin , your doctor can determine if you have anemia. A normal reading for women is 12 to 16 grams of hemoglobin per deciliter of blood 14 to 18 grams is normal for men, according to the Mayo Clinic.

If blood work reveals anemia, your doctor will give you an exam and other blood tests to find the cause. In people with psoriatic arthritis, treatments that reduce inflammation also help with anemia, explains Cadet.

Frequency of Testing Doctors may order tests to be done several times a year to see if the anemia has worsened or improved.

Additional reporting by .

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Treatment For Psoriatic Arthritis

Treatment for psoriatic arthritis aims to:

  • relieve symptoms
  • slow the conditions progression
  • improve quality of life

This usually involves trying a number of different medicines, some of which can also treat the psoriasis. If possible, you should take 1 medicine to treat both your psoriasis and psoriatic arthritis.

The main medicines used to treat psoriatic arthritis are:

  • non-steroidal anti-inflammatory drugs

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Treatment Options For Ra And Psa

Psoriatic or Rheumatoid Arthritis

Because of the differences in disease pathogenesis, clinical manifestations and response to therapy between RA and PsA, treatment strategies may differ. provides a summary of current Food and Drug Administration -approved treatments for RA and PsA. Agents targeting more upstream factors are effective in both PsA and RA, while agents targeting more downstream cytokines are more disease-specific, demonstrating significant efficacy in either RA or PsA , but not in both diseases.

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Psoriatic Arthritis Diagnostic Criteria

It isnât easy to diagnose psoriatic arthritis — many of the symptoms are similar to other conditions. Your doctor has a set of things to look for called criteria. These include:

Classification of Psoriatic Arthritis

This method uses a points system to scale your symptoms. At least 3 points indicates psoriatic arthritis:

  • You have it now = 2 points
  • You had it = 1 point
  • You have a family history = 1 point
  • Nail lesions = 1 point
  • Dactylitis = 1 point
  • Negative rheumatoid factor: You donât test positive for this blood protein that signals rheumatoid arthritis = 1 point
  • Juxta-articular bone formation that shows up on X-ray and isnât bone spurs = 1 point
  • Psoriatic Arthritis Blood Test: Rheumatoid Factor

    Rheumatoid factor , a protein produced by the immune system that attacks healthy tissue, is an indication of systemic inflammation.

    Although RF is mostly associated with rheumatoid arthritis, it can also occur in a small percentage of people with psoriatic arthritis, says Rubenstein. To distinguish the two conditions, doctors will look at RF levels in the context of other factors, such as a certain pattern of joint involvement and symptoms of psoriasis, which can accompany psoriatic arthritis.

    Frequency of Testing This is usually done only at the initial diagnostic appointment, says Rubenstein.

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    Is Psoriatic Arthritis Genetic

    There is no single gene that causes psoriatic arthritis to develop, but experts believe there is probably a genetic component9, 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 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 arthritis10. 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.

    Inflammation And Other Forms Of Arthritis

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    Some infections can lead to joint destruction and this occurs much quicker than with other forms of arthritis. It is crucial to rule out an infection when arthritis affects a single joint.

    Gout: A common and painful condition that affects the joints and tendons. Small crystals of uric acid form in and around the joint which causes inflammation, pain and swelling. An attack of gout usually comes on very quickly, often overnight. The joint becomes red, swollen and painful. It often affects one joint at a time, such as the big toe.

    Inflammation: A localised physical condition in which part of the body becomes reddened, swollen, hot, and often painful. Inflammation is a common symptom of arthritis, and is the cause and the result of all forms of arthritis.

    This info sheet was reviewed and updated by Prof. Susanna Proudman, Medical Director, Arthritis Australia and Dr Stephen Adelstein, Pathology Awareness Australia ambassador.

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    Clinical Characteristics Of Ra And Psa

    For RA, the American College of Rheumatology /European League Against Rheumatism classification criteria were designed for patient characterisation and use in clinical trials. The key clinical characteristic is the confirmation of definite, persistent, clinical synovitis in at least one joint. The criteria include the number of joints involved, duration of symptoms, and the demonstration of serological markers and an elevated acute-phase reactant. For PsA, the Classification Criteria for Psoriatic Arthritis help categorise patients with inflammatory articular disease for clinical trials. Key clinical characteristics include a personal or family history of psoriasis, psoriatic nail dystrophy and dactylitis. Neither classification criteria should be confused as diagnostic criteria.

    Joint involvement is predominantly symmetric in RA and often, but not always, asymmetric in PsA. In both RA and PsA, most patients have polyarthritis , although joint involvement can be oligoarticular or polyarticular. Monoarticular disease is less common in PsA however, 5%10% of patients may present with isolated distal joint involvement. In PsA, prognosis worsens and symmetry of joint involvement tends to increase as the number of affected joints increases.

    Rheumatoid Factor Blood Test

    Rheumatoid factor is a type of protein known as an autoantibody. Because RF targets the bodys own healthy tissues, elevated levels of the substance in the blood often indicate the presence of an autoimmune disease.

    As its name suggests, a rheumatoid factor blood test is often used to screen for rheumatoid arthritis . During this test, your doctor will draw a small sample of blood usually from a vein in your arm and send it off for laboratory testing. Lab technicians will assess the levels of rheumatoid factor in your blood.

    Positive RF test results indicate that your body is producing more rheumatoid factor antibodies than it normally would. Generally, the normal range for RF is between 0 IU/mL and 15 IU/mL. Mild elevation in the upper teens and 20s isnt usually a cause for concern. However, significantly higher rheumatoid factor results may indicate unusual autoimmune activity.

    While doctors frequently order rheumatoid factor blood tests to confirm RA, the test can also indicate other RF-elevating diseases, such as cancer, Sjogrens syndrome, systemic lupus erythematosus , and sarcoidosis. That said, the test isnt perfect. According to the The United Kingdoms National Health Service, about one in 20 people without RA still receive positive RF results. Some may have one of the diseases mentioned above, while others may be healthy and simply have a high rheumatoid factor.

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    Early Warning Signs You Have Psoriatic Arthritis

    Autoimmune disorders can be difficult to diagnose, especially in the earlier stages, and psoriatic arthritis is no different. Because there is no definitive blood test that can identify this form of arthritis and the similarities in symptoms it shares with rheumatoid arthritis, diagnosing can be tricky.

    Research suggests that more than half of people with psoriatic arthritis must wait at least two years for a diagnosis, so it can be helpful to recognize the symptoms early on. Keep reading to learn about the early signs of psoriatic arthritis and how to find someone who can help provide you some relief.

    Key Points About Psoriatic Arthritis

    Psoriatic Arthritis Diagnosis | Johns Hopkins Medicine
    • Psoriatic arthritis is a form of arthritis with a skin rash.
    • Psoriasis is a chronic skin and nail disease. It causes red, scaly rashes and thick, pitted fingernails. The rash may come before or after the arthritis symptoms.
    • Psoriatic arthritis causes inflamed, swollen, and painful joints. It happens most often in the fingers and toes. It can lead to deformed joints.
    • Treatment may include medicines, heat and cold, splints, exercise, physical therapy, and surgery.

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    Radiographic Features Of Ra And Psa

    Use of imaging can provide important information to help practitioners identify and differentiate between types of inflammatory arthritis. Conventional radiography can be used to identify juxta-articular bony proliferations, which can be used to help discern PsA from other types of inflammatory arthritis, and to visualise osteodestructive lesions characteristic of RA. Other characteristic radiographic changes observed in patients with severe PsA are bone resorption, pencil-in-cup deformities and ankylosis. However, conventional radiographs are not as sensitive as ultrasound or MRI for detection of bone erosions and may not help clinicians detect soft-tissue changes well. Additionally, in our experience, radiologists will often report changes consistent with osteoarthritis in patients with PsA, and it is necessary for rheumatologists to interpret these findings in the proper clinical context.

    Ultrasound imaging can be used to identify characteristic features of inflammatory arthritis, including enthesitis, cortical bone erosions, cartilage lesions, synovitis and tenosynovitis. Bone erosions are an important diagnostic criterion of RA that can be identified based on intra-articular discontinuity of the bone surface. Ultrasound evaluations of bone erosions are more reliable for joints that are easily accessible than for carpal or tarsal bones, which cannot be viewed circumferentially.

    Psoriatic Arthritis Blood Test: Erythrocyte Sedimentation Rate

    Erythrocyte sedimentation rate, or ESR or sed rate, is a blood test that measures inflammation in the body, which helps determine a psoriatic arthritis diagnosis, explains Elaine Husni, MD, MPH, vice chair of rheumatology and director of the Arthritis and Musculoskeletal Center at the Cleveland Clinic.

    The test measures how many milliliters of red blood cells settle per hour in a vial of blood. When swelling and inflammation are present, the bloods proteins clump together and become heavier as a result, they will fall and settle faster at the bottom of the test tube, according to Johns Hopkins Medicine.

    As with many blood tests, labs each have their own, slightly different reading of what ESR numbers mean, which they interpret based on past results, explains Cadet. Age is also a factor. ESR can be elevated slightly in elderly patients and still be normal for that person, she says.

    Frequency of Testing In addition to diagnosis, Testing may be done several times a year to determine if theres ongoing inflammation, says Cadet.

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    Psoriatic Arthritis Imaging Test: Bone Mineral Density

    The most common bone mineral density test is called DXA , for dual-energy X-ray absorptiometry. This test uses X-rays to measure how many grams of calcium and other bone minerals are packed into a segment of bone. The denser the bones, the stronger and healthier they are.

    Unfortunately, common psoriatic arthritis medications such as prednisone, a corticosteroid can weaken bones over time and increase the risk of osteoporosis. And psoriatic arthritis itself is associated with a decrease in bone mineral density, notes Rubenstein.

    If youre diagnosed with osteopenia, a condition involving weakened bones that may lead to osteoporosis, your doctor will discuss medications that can slow or stop bone loss, and may recommend calcium and vitamin D supplements along with resistance exercise, says Rubenstein.

    Frequency of Testing Bone density screening is done during menopause and every one to two years after that, says Rubenstein. If a patient is on prednisone or other medications that decrease bone mineral density, the test may be done earlier and repeated every one to two years.

    Who Develops Psoriatic Arthritis

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    You may experience PsA after you develop psoriasis. About 30 percent of people with psoriasis go on to develop PsA. And its estimated that 85 percent of people with PsA developed psoriasis first.

    Keep in mind that while the two conditions are linked, your experience with each can be quite different. For example, you may have limited psoriasis symptoms but severe PsA.

    Psoriasis and PsA are both autoimmune conditions. It isnt known what specifically leads to psoriasis or PsA. One factor could be genetics. About 40 percent of people with these conditions have a family member with the same condition.

    Other risk factors include certain age and infections that trigger the immune system. Most people diagnosed with the condition are in their 30s or 40s.

    You may be diagnosed with PsA after testing. Then, your doctor will determine a treatment plan for your level of PsA based on your test results, symptoms, and overall physical health.

    Your treatment plan may include one or more of the following:

    • nonsteroidal anti-inflammatory drugs

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    How To Talk To Your Health Care Provider About Symptoms

    By taking this short screening assessment, the Psoriasis Epidemiology Screening Tool , you may help your health care provider make a diagnosis.

    Bring your quiz results and the diagram to your appointment. Circle all of the places on the diagram where your body feels tender or sore. This way, you wonât forget to mention important symptoms. Even if youâre not feeling them on the day of your appointment, you should still bring them up with your provider.

    Describe symptoms as precisely as possible. For example, instead of saying, âMy knee hurts,â say âThere is a sharp, piercing pain on the outside of my left knee, under the kneecap.â

    Prepare five main questions youâd like to ask your provider. Youâre probably wondering about many things concerning your health right now. Boiling them down to five main questions will help focus your conversation with your provider, and give your provider enough time to give you complete answers.

    For example, you could ask about:

    • Symptoms you are experiencing
    • New medications or dietary supplements
    • Information from other health care providers you see
    • Treatments you are interested in
    • How treatments might affect you

    Be specific, open and honest. If you donât understand anything your health care provider is saying, speak up. Also, if your provider is recommending a treatment that you donât think is right for you, say so. Itâs OK to ask about other treatment options.

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