Blood tests for psoriatic arthritis


Blood tests for psoriatic arthritis 

Blood tests can help to diagnose psoriatic arthritis (PsA) or to rule out other conditions that cause similar symptoms. Regular blood tests are also used to:

  • monitor disease activity
  • check if your PsA treatment is working
  • check for side effects from your medicines.

Types of blood tests 

Erythrocyte Sedimentation Rate (ESR): ESR tests measure the level of inflammation in the body. However, the test does not show exactly where in the body the inflammation is or what is causing it. ESR can also be affected by other conditions, so it is used alongside other tests to help determine if you have PsA.

C-Reactive Protein (CRP): CRP is a substance that the liver makes in response to inflammation. CRP tests measure the level of inflammation in the body by measuring the amount of C-reactive protein in the blood. The test is not specific enough to diagnose a particular type of arthritis or disease, so it is used alongside other tests.

Rheumatoid Factor (RF): RF is a protein made by your immune system.  The RF test is commonly used to help diagnose rheumatoid arthritis (RA).  RA and PsA often have similar symptoms.  However, people with RA tend to have a high amount of RF in their blood while people with PsA are almost always RF-negative. So, RF can be used to help rule out RA, along with other tests, to help reach a PsA diagnosis.

Anti-Cyclic Citrullinated Peptide antibody (anti-CCP):  Like RF, the anti-CCP antibodies (proteins made by the body’s immune system) are commonly present in people with RA. This test can help rule out RA.

Antinuclear Antibody (ANA): Like RF, ANA is a protein produced by the immune system. The ANA test screens the amount of ANA in the body. A large amount may suggest an autoimmune disorder, such as PsA. Further testing, along with the patient’s symptoms and signs, is usually needed to make a final diagnosis.

HLA-B27: A gene called HLA-B27 is linked to PsA. Your doctor may suggest you have a blood test to find out if you have this gene. However, there are many people who have this gene and do not get PsA. 


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 don’t 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.