Quick answer: Arthritis is diagnosed by putting together your symptoms, an examination of your joints and, when needed, blood tests and scans. Osteoarthritis can often be diagnosed without any tests if you are over 45 with typical symptoms. Inflammatory types, such as rheumatoid arthritis, usually need blood tests like CRP, ESR, rheumatoid factor and anti-CCP, plus a specialist assessment. No single test confirms most types of arthritis.
The first step: your story
The most useful part of diagnosing arthritis is often the conversation. Your GP, physiotherapist or first contact practitioner will want to know which joints hurt, when the pain started, what makes it better or worse, and how it affects your daily life. Some patterns point strongly towards one type of arthritis rather than another.
- Stiffness that lasts more than about half an hour in the morning, with swollen, warm joints, suggests inflammation, as in rheumatoid arthritis or psoriatic arthritis.
- Pain that gets worse with use and eases with rest, with short-lived stiffness, is more typical of osteoarthritis.
- Sudden, very painful attacks in one joint, often the big toe, suggest gout.
- Back pain and stiffness that improve with movement and wake you in the second half of the night may point to axial spondyloarthritis.
It helps to bring notes: when symptoms started, which joints are affected, photos of any swelling or rashes, family history of arthritis or psoriasis, and a list of your medicines. Our guide to early signs of rheumatoid arthritis may help you describe what you have noticed.
The examination
The clinician will look at and feel your joints, checking for swelling, warmth, tenderness, creaking, and how far each joint moves. They may look at your skin and nails for signs of psoriasis, check your spine, and ask you to walk, squat or grip. Swollen joints that feel soft or "boggy" are an important sign of inflammation and usually lead to an urgent referral to rheumatology.
Blood tests
Blood tests can support a diagnosis, rule out other causes and give a baseline before treatment. None of them is perfect. Some people with arthritis have normal results, and some people without arthritis have abnormal ones. The most common tests include:
- CRP (C-reactive protein) and ESR (erythrocyte sedimentation rate): general markers of inflammation. They rise in inflammatory arthritis but also with infections and many other conditions. They are often normal in osteoarthritis.
- Rheumatoid factor (RF): an antibody found in many, but not all, people with rheumatoid arthritis. It can also be positive in healthy people, particularly as they get older, and in some other conditions.
- Anti-CCP antibodies: more specific for rheumatoid arthritis than rheumatoid factor. A positive result makes rheumatoid arthritis more likely.
- ANA (antinuclear antibodies): used when lupus or a related condition is suspected. A positive ANA is common in healthy people, so it is interpreted alongside symptoms and other tests.
- Urate (uric acid): helps in assessing gout, although levels can be normal during an attack.
- HLA-B27: a genetic marker linked to axial spondyloarthritis. Many people with it never develop the condition.
- Full blood count, kidney and liver function, thyroid tests and vitamin D: to check general health, look for other causes of symptoms, and provide a baseline before medicines are started.
If a test is "negative" it does not always rule arthritis out. For example, some people have seronegative rheumatoid arthritis, where RF and anti-CCP are both negative. That is why examination and specialist opinion matter so much.
Scans and imaging
- X-rays show bones and the space between them, which narrows when cartilage thins in osteoarthritis. Early inflammatory arthritis may not show on X-ray at all. X-rays are also used as a baseline to track any joint damage over time.
- Ultrasound can show inflammation in the joint lining and tendons, even when it is hard to feel. Many rheumatology departments use it in clinic.
- MRI gives detailed pictures of bone, cartilage and soft tissues. It is especially useful for the spine and sacroiliac joints when axial spondyloarthritis is suspected.
- CT and DEXA scans are used in specific situations, such as looking at complex joints or measuring bone density for osteoporosis.
NICE guidance advises that osteoarthritis can usually be diagnosed clinically, without imaging, in people aged 45 or over with activity-related joint pain and short-lived morning stiffness. Scans are kept for when symptoms are unusual or when the result would change what happens next.
Joint fluid tests
If a joint is swollen, a doctor may draw off some fluid with a needle. Looking at the fluid under a microscope can show crystals, which confirm gout or pseudogout, and testing it can show whether there is infection. A hot, swollen, very painful joint with fever needs same-day assessment, as it could be septic arthritis.
Seeing a rheumatologist
If your GP suspects inflammatory arthritis, NICE recommends urgent referral to a specialist rheumatology service, because early treatment improves long-term outcomes. The GP should not wait for blood test results before referring if you have persistent swollen joints. At the rheumatology clinic you will have a fuller assessment and may have further tests or an ultrasound on the day.
If you are waiting for an appointment and your symptoms get much worse, contact your GP or the rheumatology department. Our newly diagnosed guide covers what to expect next.
Understanding your results
- You can usually see your blood test results in the NHS App or ask your GP practice for a copy.
- Reference ranges vary between laboratories. A result just outside the range may not mean anything significant.
- Results are always interpreted alongside your symptoms and examination. Ask your clinician what each result means for you.
- If you are told your tests are normal but you still have symptoms, it is reasonable to ask what else could explain them and what the plan is.
Getting a clear diagnosis can take time
Some conditions develop gradually, and the picture becomes clearer over months. You may be told you have "undifferentiated" or "early" inflammatory arthritis at first. This can feel frustrating, but it does not mean nothing can be done. Treatment for symptoms can often start while the diagnosis is confirmed. Keep a symptom diary and keep in touch with your team.
Frequently asked questions
Can a blood test show arthritis?
Blood tests can support a diagnosis of some types of arthritis, such as rheumatoid arthritis, but no single test confirms or rules out most types. Results are combined with your symptoms and an examination.
Do I need an X-ray to diagnose osteoarthritis?
Often not. If you are 45 or over with typical symptoms, osteoarthritis can usually be diagnosed from your history and an examination.
What does a raised CRP mean?
CRP rises with inflammation, which can be caused by inflammatory arthritis, infection or many other conditions. Your clinician will interpret it alongside your symptoms.
Can you have rheumatoid arthritis with a negative rheumatoid factor?
Yes. Some people have seronegative rheumatoid arthritis. Anti-CCP, examination and scans help in diagnosis.
How long does it take to see a rheumatologist?
It varies by area. NICE recommends urgent referral for suspected persistent inflammatory arthritis. If symptoms worsen while you wait, contact your GP or the rheumatology department.
Should I ask for a copy of my test results?
Yes, it can help you understand your condition. Many results are available in the NHS App.
Sources and further reading
- NHS: Rheumatoid arthritis diagnosis
- NICE NG100: Rheumatoid arthritis in adults
- NICE NG226: Osteoarthritis in over 16s
- NHS: Blood tests
This guide is for general education and is not a substitute for personal medical advice. Everyone's situation is different, so always follow the advice of your own GP, pharmacist or rheumatology team. If you feel very unwell, call 999 or go to A&E. For urgent advice, contact NHS 111.