Blood And Pathology Tests For Arthritis
Before any tests are done, the doctor will ask you about your symptoms and will often examine you for signs of arthritis or other autoimmune features. Then tests may be done.
Your symptoms and signs on physical examination are more important for making a diagnosis than the results of the tests.
What are blood tests and pathology tests used for?
- Confirming a diagnosis of arthritis or autoimmune disorder
- Monitoring disease activity and response to treatment
- Checking for side effects from medicines
Are all types of arthritis diagnosed by blood tests?
Most forms of arthritis can be diagnosed by blood tests. The doctor may use blood tests to provide support for the diagnosis made on the symptoms and signs, or to help rule out other types of arthritis or conditions that cause similar symptoms. No blood or pathology tests may be required to diagnose some conditions such as osteoarthritis or chronic back pain.
What If Your Bloodwork Is Normal
Often patients with PsA will have normal CRP and ESR levels. Similarly, while anti-CCP is typically an RA indicator, anti-CCP can be both negative or positive in PsA.
While bloodwork is certainly part of the diagnostic process, patient history and a physical examination are the most important factors to correctly diagnose PsA.4,9
Assessing The Immune System
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
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What Is A Rheumatologist
A rheumatologist is a specialist in the nonsurgical treatment of autoimmune, inflammatory, or other musculoskeletal conditions commonly referred to as rheumatic diseases.
Your rheumatologist is the best person to:
- Confirm your diagnosis after reviewing all test results and your medical history
- Direct you toward the best treatment depending on the severity of your psoriatic arthritis and whether the symptoms are mostly external , internal , or a combination of both.
Inflammation And Other Forms Of Arthritis
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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What Is A Uric Acid Test
Another test used to mainly rule out another condition similar to PsA is a uric acid test. Uric acid tests are often used to diagnose gout. Patients with gout typically have a build-up of uric acid in the joints and surrounding tissues, which can form crystals that cause swelling and pain.
Some doctors may continue to repeat uric acid tests after you have been diagnosed with PsA. There is some evidence that there could be a connection between gout and PsA when it comes to uric acid.
Studies have shown that the inflammation experienced in PsA can cause uric acid to build up, which can increase the risk of gout down the road.5
Having Psoriasis Isnt Always A Reliable Clue
Around 70 percent of people with psoriatic arthritis develop psoriasis first, but in the other 30 percent of the time, the arthritis and skin symptoms occur around the same time, people have psoriasis but dont realize it, or the psoriasis may develop later on after the arthritis-like symptoms show up. Some people can develop psoriatic arthritis without having psoriasis.
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What Other Tests Are Used To Diagnose Psoriatic Arthritis
While X-rays are important to help determine damage by arthritis, such imaging tests cant confirm PsA alone. Part of this is due to the fact that other types of arthritis, such as rheumatoid arthritis , may look similar on X-rays.
To distinguish PsA from other autoimmune conditions that affect the joints, your doctor will need to run other exams and tests to provide an accurate diagnosis. These include:
Psoriatic Arthritis Blood Test: C
C-reactive protein is a protein in the blood that indicates inflammation. If a blood test shows high CRP levels, you might have psoriatic arthritis, explains Dr. Husni.
Your doctor may use the test if your ESR is normal, since CRP is more accurate at detecting inflammation in some people, adds Cadet.
Again, different labs may have slightly different interpretations of readings.
Frequency of Testing CRP analysis may be done for diagnosis and then several times a year to assess whether inflammation has responded to treatment, notes 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.
Symptoms Of Psoriatic Arthritis
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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How Psoriatic Arthritis Is Diagnosed According To A Rheumatologist
Psoriatic arthritisan inflammatory and chronic type of arthritisaffects up to 30 percent of people with psoriasis, according to the National Psoriasis Foundation . If you have psoriasis, its a good idea to be aware of the symptoms of psoriatic arthritis , because catching it early, if it does develop, may improve treatment outcome.
If you do notice the telltale signs of PsA, such as pain and stiffness in the joints, whats the next step? Unfortunately, theres no single test that can diagnose PsA with a yes-or-no answer. Instead, a combination of different exams can help doctors form a PsA diagnosis, according to Leah Anon, MD, rheumatologist at Harlem Health Center and Queens Health Center in New York City.
Here are the factors doctors consider before diagnosing with PsA:
The patients symptoms, including when they started, where the stiffness is occurring, and how much it impacts daily life
Personal history of psoriasis
An X-ray or MRI to check for inflammation or damage to the joints
And blood tests to rule out other conditions.
Other Conditions to Rule Out
Many health conditions can cause joint pain, and psoriatic arthritis can mimic some of them. In particular, doctors need to rule out other types of arthritis like rheumatoid arthritis and gout, according to NPF. Many blood tests used to diagnose PsA are actually meant to rule out these similar conditions.
Although symptoms of the different conditions are similar, they have some key differences:
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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Complete Medical History For Diagnosing Psoriatic Arthritis
Your road to a psoriatic arthritis diagnosis starts with talking to your rheumatologist in order to share symptoms and identify risk factors. While symptoms like joint pain could suggest a number of conditions, in psoriatic arthritis, joint pain often has specific characteristics, including the following:
- Joint pain that gets better with use
- Joint redness and swelling
- Swelling of an entire finger or toe as opposed to just one joint, called dactylitis or sausage digits
- Morning stiffness that lasts more than 30 minutes
- Changes in the nails of your fingers or toes, such as holes, pitting, discoloration or softness, which occurs in 80 to 90 percent of PsA cases
When patients talk about these psoriatic arthritis symptoms, rheumatologists like Dr. Kumar hear a number of common concerns, such as My shoes dont fit, I feel stiff all over in the mornings, and I have trouble opening jars or door knobs.
Along with listening to your symptoms, your rheumatologist will want to hear about any possible risk factors for psoriatic arthritis. While this condition can affect patients of both genders at a range of ages, the following can increase your risk:
- Having psoriasis
- Having a family history of PsA, psoriasis, or associated conditions, including ankylosing spondylitis, Crohns disease, ulcerative colitis, autoimmune uveitis, and reactive arthritis
A Thorough Medical History
Your personal medical history is an important factor to consider when diagnosing PsA. Your doctor will ask questions about your symptoms, including their severity and when you first noticed them.
Additionally, your doctor will ask about any personal or family history of psoriasis, PsA, and other autoimmune conditions. Psoriasis may increase your chances of developing PsA, and both conditions can run in families.
Having a family history of autoimmune diseases may also increase your personal risk of developing PsA even if your parents or relatives have other types of autoimmune conditions.
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What Causes Psoriatic Arthritis
The cause of psoriatic arthritis is unknown. Researchers suspect that it develops from a combination of genetic and environmental factors. They also think that immune system problems, infection, obesity, and physical trauma play a role in determining who will develop the disease. Psoriasis itself is neither infectious nor contagious.
Recent research has shown that people with psoriatic arthritis have an increased level of tumor necrosis factor in their joints and affected skin areas. These increased levels can overwhelm the immune system, making it unable to control the inflammation associated with psoriatic arthritis.
Types Of Psoriatic Arthritis Tests
If your doctor suspects you may have psoriatic arthritis, a number of tests may be used to help diagnose psoriatic arthritis and rule out other conditions. Several tests are designed to detect antibodies, which are proteins that help coordinate immune responses. The table below lists tests that are often used during the process of diagnosing psoriatic arthritis:
|Tests Related to Diagnosing Psoriatic Arthritis|
|Detects and measures a number of substances in urine||Excess protein in the urine is common in PsA.|
Imaging tests are commonly used in the diagnosis of psoriatic arthritis. They can detect certain types of joint damage and deformity that are more common in psoriatic arthritis than in other joint diseases. X-rays are most typically used, but other tests like MRIs and CT scans may also be ordered.
Many doctors use the Classification of Psoriatic Arthritis criteria to make a diagnosis of psoriatic arthritis. This tool takes into account many typical features of psoriatic arthritis, such as skin psoriasis, nail lesions, swelling of the fingers or toes, a negative rheumatoid factor test, and new bone formation seen on imaging tests.
If psoriatic arthritis is diagnosed, your doctor may order additional lab tests before you begin treatment. Health issues such as heart disease, kidney or liver abnormalities, or infections may be taken into consideration when your treatment is planned. Sometimes, infections will be treated before treatment begins.
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The Role Of Psoriatic Arthritis Tests
Psoriatic arthritis testing is used to help diagnose the disease, to evaluate your suitability for certain treatments, and to monitor for treatment effects.
No single test can diagnose or rule out psoriatic arthritis. This disease is diagnosed by a physician who uses a range of information, including:
- Family and medical history
- Heel pain
- Swollen fingers or toes
If you have symptoms of psoriatic arthritis, it is a good idea to discuss your concerns with your doctor. Early diagnosis and treatment can help prevent the severe joint damage that may occur if the disease progresses.
Living With Psoriatic Arthritis
There is no cure for psoriatic arthritis. However, by understanding the disease and knowing what to expect, you can learn different ways to complete daily tasks or plan activities at times of the day when you are least bothered by its effects. Once you understand and learn to predict the ways in which your body responds to the disease, you can use exercise and therapy to help decrease discomfort, stress and fatigue.
There is a significant list of comorbidities related to PsA. These include these 11 conditions:
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Key Points About Psoriatic Arthritis
- 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.
Does Medicare Cover The Cost
The costs of different types of blood tests may vary. Medicare generally covers all or part of the cost for blood tests. Most blood tests are bulk billed, so you dont have to pay anything. Check with your doctor about how much the blood test will cost and whether Medicare will cover all or part of the amount.
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Psoriatic Arthritis Blood Test: Anti
Blood tests that look for the presence of anti-cylic citrullinated peptide antibodies , which are inflammatory, are commonly used to diagnose rheumatoid arthritis, but anti-CCPs can also indicate psoriatic arthritis.
Roughly 8 to 16 percent of people with psoriatic arthritis will test positive for anti-CCPs, says Rubenstein.
Frequency of Testing Some physicians will perform the test yearly, says Cadet.
Treatment For Psoriatic Arthritis
Treatment for psoriatic arthritis aims to:
- relieve symptoms
- slow the condition’s 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
- biological therapies
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Other Tests For Psoriatic Arthritis
You will likely also be required to take the following tests for your diagnostic examination to be considered complete:
- Bone density scans can check for joint damage or bone loss and look for other conditions like osteoporosis , osteopenia , and demineralized bones .
- Imaging tests like X-rays and MRIs are used to examine bones and joints in detail to see the level of damage or inflammation.
How Is Psoriatic Arthritis Treated
Treatment will depend on your symptoms, age, and general health. It will also depend on the severity of your condition.
Boththe skin condition and the joint inflammation are treated. Early diagnosis andtreatment helps prevent joint damage. Some medicines used to treat psoriatic arthritisinclude:
- Nonsteroidal anti-inflammatory medicines to ease symptoms
- Corticosteroids for inflammation
- Immunosuppressive medicines such as methotrexate to reduce inflammation if NSAIDs don’t work
- Biologic medicines to ease inflammation
- Vitamins and minerals such as calcium and vitamin D to slow bone deformation
Other treatment may include:
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