Undifferentiated connective tissue disease (UCTD) is a type of autoimmune disease. It can cause symptoms like joint pain and swelling, skin symptoms, and more.

The exact prevalence of UCTD is unknown, but it’s believed to be one of the more common conditions seen in rheumatology clinics. In fact, it may account for 10% to 20% of referrals to rheumatology specialists.

Making a diagnosis of UCTD is difficult due to its overlap with other conditions.

Below, we’ll go over more details on UCTD, the types of symptoms that can occur, as well as how it’s diagnosed and treated.

UCTD is an autoimmune disease. This is when your immune system mistakenly attacks healthy organs and tissues in your body.

In UCTD, it’s the body’s connective tissue that’s primarily affected. Connective tissue is found throughout your body. It’s important for supporting your organs and helping to maintain their structure. While UCTD will affect connective tissue, it can also involve other parts of the immune system as well as other body structures.

There are many different types of connective tissue diseases (CTDs) that can happen due to autoimmune activity. These include:

Each of the conditions above has a specific set of diagnostic criteria. When your condition doesn’t meet the criteria for any other CTDs, UCTD is diagnosed.

The exact cause of autoimmune diseases like UCTD is unknown. However, it’s likely that it occurs due to a combination of genetic and environmental factors.

The symptoms of UCTD happen when your immune system begins to attack healthy connective tissue in your body. This leads to increases in inflammation that may lead to tissue damage.

UCTD overwhelmingly impacts people who are female. It’s estimated that up to 90% of people with diagnosed UCTD are female. Many of these individuals receive the diagnosis in their 30s or 40s.

Initial symptoms of UCTD can be nonspecific and can include things like:

Overall, the symptoms of UCTD can vary greatly between individuals. However, some of the more common symptoms include:

Other potential findings can be:

When to see a doctor

The symptoms of UCTD can overlap with a variety of other health conditions, especially other autoimmune diseases. If you develop any of the symptoms above, make an appointment with a doctor.

It’s especially important to see a doctor if you have symptoms that:

  • are severe
  • are persistent
  • recur frequently
  • get worse with at-home care
  • can’t be explained by another health condition
  • affect your quality of life

The diagnosis of UCTD disease requires a careful evaluation by a doctor. This is because the symptoms of UCTD overlap with those of several other autoimmune diseases, increasing the risk of a misdiagnosis.

The diagnosis is one of exclusion. This means that other conditions need to be ruled out before arriving at a diagnosis of UCTD.

A doctor will consider your symptoms and the results of various tests to see if your condition fits into any of the defined diagnostic criteria for other CTDs. If not, UCTD will be diagnosed.

Diagnostic tests that a doctor may use

Blood tests are very important in the diagnostic process. After taking your medical history and doing a physical examination, a doctor may order the following blood tests:

  • Autoantibody tests: Autoantibodies are often present in autoimmune diseases. These are antibodies that attack healthy tissues and can be markers for certain conditions. Some examples of autoantibodies a doctor will test for are:
    • rheumatoid factor (RF), an autoantibody that’s often associated with RA but can also be found in other autoimmune diseases
    • anticyclic citrullinated peptide (anti-CCP), an autoantibody present in most people with RA
    • anti-Ro/SSA, an autoantibody that’s typically associated with Sjögren’s disease but can be also found with other autoimmune diseases
    • anti-U1-RNP, a type of autoantibody associated with MCTD
  • Complete blood count (CBC): A CBC measures the levels of different types of blood cells in your body.
  • Tests for inflammation: Autoimmune diseases are associated with increases in inflammation. Some tests, such as C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) tests, can be used to look for signs of inflammation in the body.
  • Metabolic panel: A metabolic panel is used to assess your overall health. It can measure things like liver and kidney function, blood sugar, and levels of different electrolytes in the blood.
  • Urinalysis: This test looks for elevated levels of proteins and red or white blood cells.

It’s possible that additional more specialized blood tests will also be ordered as a doctor tries to determine the cause of your symptoms. Other types of tests that may also be helpful include:

Treatment isn’t always needed for UCTD. If symptoms are mild, many cases are followed over time to see if they develop into a more specific autoimmune disease. If treatment is needed, it focuses on reducing immune system activity. This helps prevent your immune system from continuing to attack healthy connective tissue.


Some examples of medications that may be used include:

Lifestyle remedies

Along with taking your medications as directed by a doctor, there are also things that you can do in your daily life to help with UCTD. These include:

Many people with UCTD have only mild symptoms. However, the exact course of the disease depends on how many areas of the body are affected.

When major organs like the lungs, heart, and kidneys are impacted, complications can occur. For example, interstitial pneumonia can cause scarring in the lungs, while heart involvement can lead to enlargement of the heart.

Many people with UCTD continue to have UCTD. However, the condition can also progress into another defined type of CTD, such as RA or SLE. This happens in between 20% and 40% of people.

The likelihood of progression is highest in the first 5 years after your symptoms start. After this, progression is still possible but is less likely.

It’s also important that pregnant people with UCTD be carefully monitored. This is because individuals with detectable disease activity have a higher risk of flare-ups, progression to a defined CTD, and poor pregnancy outcomes.

UCTD is an autoimmune disease. It’s diagnosed when your symptoms don’t fit with those of a defined connective tissue disorder like SLE or RA.

The symptoms of UCTD can vary greatly from person to person. They can also overlap with symptoms of other CTDs, making UCTD particularly challenging to diagnose.

Most of the time, UCTD is mild, although it may progress to a defined CTD in some situations. Be sure to see a doctor if you have unexplained, persistent, or recurring symptoms that are consistent with an autoimmune disease like UCTD.