If you have thumb pain you may have heard the word rhizarthrosis. This is a kind of arthritis at the base of the thumb. But thumb pain can also be a sign of other health problems.
A recent study looked at over 1,000 people with hand pain. The doctors wanted to see who had autoimmune diseases and who had other problems. They found some important clues to help doctors tell the causes apart.
Here are three key points from this research:
- About 1 in 10 people with hand pain had a systemic autoimmune disease
- Certain blood tests and imaging tests can help find the cause of thumb and hand pain
- Rhizarthrosis showed up differently on ultrasound than autoimmune diseases
Key Findings at a Glance
- Research shows that 9.6% of patients with hand pain had systemic autoimmune rheumatic diseases (SARD)
- Among those with autoimmune diseases, lupus was the most common at 47%
- People with rhizarthrosis had specific patterns on ultrasound that were different from autoimmune diseases
- Blood tests like ANA (antinuclear antibody) showed positive in 82% of autoimmune disease cases
- Ultrasound was helpful for telling the difference between autoimmune inflammation and regular arthritis
What did this study find?
Researchers followed 1,053 people who were at least 18 years old. All of these people had hand pain. The doctors checked them using blood tests, ultrasound pictures, and X-rays. Then they watched to see what diagnosis each person ended up with.
You may be wondering why this matters.
According to this study, out of all those people, 101 patients (9.6%) had systemic autoimmune rheumatic diseases. These are conditions where the body’s defense system attacks its own tissues. Almost half of these people had lupus, which is also called SLE.
What are autoimmune diseases?
Your body has an immune system. This is like a security team that protects you from germs. Sometimes this security team makes a mistake. It starts attacking your own body instead of just fighting germs.
When this happens, we call it an autoimmune disease. There are many types. They can affect your joints, skin, kidneys, and other parts of your body.
Here is where it gets interesting.
Studies indicate that autoimmune diseases can show up first as hand pain. This is why doctors need to look carefully at what is causing your pain.
How is thumb arthritis different from autoimmune pain?
The researchers put people into three groups. One group had autoimmune diseases. Another group had non-inflammatory arthralgia. This means pain without swelling or immune system problems. The third group had rheumatoid arthritis, which is a specific type of autoimmune joint disease.
Research shows that people with autoimmune diseases had different signs compared to people with regular thumb arthritis. Let us look closer.
What did the ultrasound show?
Ultrasound is a test that uses sound waves to make pictures of the inside of your body. It does not hurt and it does not use radiation.
According to this study, people with autoimmune diseases showed something called power Doppler on ultrasound. This means there was active inflammation happening inside the joints. The blood was flowing faster because of swelling.
People with regular thumb arthritis (rhizarthrosis) did not show this same pattern. Instead, they showed wear and tear of the joint. In fact, when the ultrasound did NOT find rhizarthrosis, it was a clue that the person might have an autoimmune disease instead.
What did the blood tests show?
The researchers checked several things in the blood. One important test was CRP. This stands for C-reactive protein. It goes up when there is inflammation in your body.
Studies indicate that people with autoimmune diseases had higher CRP levels than people with non-inflammatory pain. When CRP was above 2.5 mg/L, it helped suggest there might be an autoimmune problem.
Another blood test looked for something called ANA. This stands for antinuclear antibodies. These are proteins that your immune system makes when it is attacking your own body.
Research shows that 82% of people with autoimmune diseases tested positive for ANA. This was much higher than in people with regular arthritis.
What tests help doctors tell the difference?
You may be wondering what tools doctors can use to figure out what is causing your pain.
According to this study, several tests worked well together:
| Test | What It Measures | How Helpful It Was |
|---|---|---|
| ANA blood test | Antibodies attacking your own cells | Found in 82% of autoimmune cases |
| Ultrasound for rhizarthrosis | Wear and tear of thumb joint | When NOT found, suggested autoimmune disease |
| CRP blood test | General inflammation level | Higher in autoimmune diseases |
| Power Doppler ultrasound | Active inflammation in joints | More common in autoimmune diseases |
When doctors compared autoimmune diseases to rheumatoid arthritis specifically, they found other differences too. People with autoimmune diseases had different pain patterns. They had fewer swollen joints. They also had less involvement of the knuckles at the base of the fingers.
What do these numbers mean?
Medical studies talk about sensitivity and specificity. These are ways to measure how good a test is.
Sensitivity means how often the test finds a problem when it is really there. Specificity means how often the test is normal when there is no problem.
Research shows that the ANA test had 82% sensitivity for autoimmune diseases when compared to non-inflammatory pain. This means it found 82 out of every 100 cases. But it only had 34% specificity. This means it also turned positive in many people who did not have autoimmune diseases.
The absence of rhizarthrosis on ultrasound had 66% sensitivity but 85% specificity. This means when the ultrasound did NOT show thumb arthritis, it was a pretty strong clue that something else was going on.
About this site
We know that medical research can be confusing. That is why this site exists. We read scientific studies about thumb pain and rhizarthrosis. Then we explain them in simple language that anyone can understand.
Every article is based only on real published research. We do not make things up or guess. We just make the science easier to read.
Feel free to explore more articles on this site. You will find helpful information about diagnosis, treatment, and living with thumb arthritis.
Frequently asked questions
Should I be worried that my thumb pain is an autoimmune disease?
According to this study, about 1 in 10 people with hand pain had an autoimmune disease. Most people had other causes like regular arthritis or non-inflammatory pain. If you have concerns, talk to your doctor. They can order blood tests and imaging to check.
What is the difference between rhizarthrosis and autoimmune arthritis?
Rhizarthrosis is wear and tear of the cartilage at the base of your thumb. It happens over time as you use your hands. Autoimmune arthritis happens when your immune system attacks your joints. Research shows that these look different on ultrasound and blood tests.
Can a blood test tell me why my thumb hurts?
Studies indicate that blood tests like ANA and CRP can give important clues. But no single test gives all the answers. Doctors use blood tests together with your symptoms, physical exam, and imaging to figure out what is causing your pain.
Is ultrasound better than X-ray for hand pain?
According to this study, ultrasound was very helpful for seeing inflammation and telling different types of arthritis apart. Ultrasound can show active swelling that X-rays might miss. Both tests give different information. Your doctor might use both.
What does this mean for you?
If you are dealing with thumb pain or pain in other parts of your hand, it is important to find out the cause. This research reminds us that not all hand pain is the same.
Researchers say that your doctor can use a mix of blood tests and ultrasound to figure out what is happening. If you have rhizarthrosis, the ultrasound will likely show wear and tear at the base of your thumb. If you have an autoimmune disease, blood tests might show certain antibodies and ultrasound might show active inflammation.
The good news is that accurate diagnosis leads to better treatment. When doctors know exactly what is causing your pain, they can recommend the right therapy for you.
If you have not already talked to your doctor about your thumb pain, now is a good time. Bring your questions. Ask about the tests mentioned in this article. Your health is worth understanding.
Important information
This article is for educational purposes only. It is not medical advice. It should not replace talking to your doctor or other healthcare provider.
Every person is different. What works for one person may not work for another. Always discuss your symptoms and treatment options with a qualified medical professional who knows your health history.
If you have severe pain, sudden swelling, or other concerning symptoms, seek medical care right away.
Research source
This article is based on research published by Sebastian, M., Jonatan, M., Alvaro, R., Santiago, R., Facundo, S., Ramiro, G., and Rodrigo, G. S. in the International Journal of Rheumatic Diseases in 2024.