A positive “autoimmune” blood test can be alarming, but it does not automatically mean you have an autoimmune disease. These tests are clues that only make sense alongside your symptoms and an examination.
Imagine aching hands and morning stiffness that lasts over an hour. Your blood test comes back with a positive rheumatoid factor and a positive ANA. You start reading about lupus and rheumatoid arthritis and fear the worst.
What autoimmune tests look for
In autoimmune diseases, the immune system mistakenly attacks the body’s own tissues. Some of these conditions produce antibodies, called autoantibodies, that can be measured in the blood. Testing for them can support a diagnosis, help predict how a condition might behave and guide treatment.
Rheumatoid factor (RF)
Rheumatoid factor is found in many people with rheumatoid arthritis, but not all. It can also be positive in other autoimmune conditions, some infections, liver disease and in a proportion of healthy people, especially older adults.,A negative RF does not rule out rheumatoid arthritis. Some people with the condition never have a positive result.
Anti-CCP antibodies
Anti-cyclic citrullinated peptide (anti-CCP) antibodies are more specific to rheumatoid arthritis than rheumatoid factor. A positive result, especially with joint symptoms, makes rheumatoid arthritis more likely. It can sometimes be positive years before joint symptoms start, and higher levels are linked to more aggressive disease.
Antinuclear antibodies (ANA)
ANA tests look for antibodies against parts of the cell nucleus. A positive ANA is found in almost all people with systemic lupus erythematosus (lupus) and is common in other conditions such as Sjögren’s syndrome, scleroderma and autoimmune liver or thyroid disease.,However, a positive ANA at a low level is also common in healthy people, particularly women and older adults. This is why ANA tests are usually only ordered when symptoms suggest an autoimmune connective tissue disease, and why a positive result on its own does not mean you have lupus.
Understanding ANA results
- Titre: how diluted the sample can be while still testing positive, for example 1:80 or 1:640; higher titres are more likely to be significant
- Pattern: such as homogeneous, speckled or nucleolar, which can hint at particular conditions
- Follow-up tests: such as anti-dsDNA and ENA antibodies, which are more specific for certain diseases
Symptoms that may suggest autoimmune disease
- Swollen, painful joints, especially small joints of the hands and feet, with morning stiffness lasting more than 30 minutes
- A rash on the face or one triggered by sunlight
- Mouth ulcers
- Fingers turning white or blue in the cold (Raynaud’s phenomenon)
- Dry eyes and mouth
- Unexplained fevers, tiredness or weight loss
- Hair loss
Other tests often done alongside
- CRP and ESR to measure inflammation
- Full blood count, kidney and liver tests
- Urine tests to check for kidney involvement
- X-rays or ultrasound of affected joints
- Complement levels in suspected lupus
Why early referral matters in inflammatory arthritis
In rheumatoid arthritis, starting treatment early, ideally within a few months of symptoms beginning, can prevent joint damage and improve long-term outcomes. If you have persistent swollen joints, ask your healthcare provider about referral to a rheumatology team, even if your blood tests are negative.
Questions to ask about your results
- Which tests were positive, and at what level?
- How do these results fit with my symptoms?
- Do I need further tests or a specialist referral?
- What symptoms should I watch for?
Frequently asked questions
Can a positive ANA become negative?
It can fluctuate, but ANA is not usually used to monitor disease activity.
Do I need to fast for these tests?
No.
Can these tests diagnose fibromyalgia?
No. Fibromyalgia is diagnosed based on symptoms, and these tests are usually normal.
But I have a positive ANA. Does that mean I have lupus?
Not necessarily. Many people with a positive ANA never develop an autoimmune disease. Your healthcare provider will look at your symptoms and other tests before making any diagnosis.
Your next step: If your hands or feet are swollen and stiff for more than 30 minutes each morning, ask your healthcare provider about inflammatory arthritis.
Related: Osteoarthritis vs rheumatoid arthritis · CRP blood test
Sources: Versus Arthritis, American College of Rheumatology, British Society for Rheumatology, Lab Tests Online UK, National Institute for Health and Care Excellence (NG100).
Leave a Reply