Rheumatoid arthritis, also known as RA, affects an estimated 1.3 million people in the United States.

Beyond this staggering statistic lies a complex reality: each person's experience with RA is uniquely their own.

Symptoms of the disease can widely differ among patients, and they can sometimes be challenging to identify.

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Whether you are seeking information for yourself or a loved one, read on to learn more about the disease and how to better understand its signs and symptoms.

Rheumatoid arthritis is an inflammatory autoimmune disease that causes the immune system to mistakenly attack its own healthy cells, according to Dr. Jason Liebowitz, assistant professor of medicine in the Division of Rheumatology at Columbia University.

The immune system is meant to fight invaders, such as outside bacteria and viruses. However, with RA, the immune system misidentifies the body's own cells for foreign entities and releases inflammatory chemicals to target them.

This often causes painful swelling in the affected parts of the body. RA commonly impacts the hands, knees or ankles, but the disease can also cause problems in the eyes, heart, circulatory system or lungs, Liebowitz said.

RA has a tendency to be mistaken for a different, more common type of arthritis, and he said it's crucial to differentiate the two.

"People colloquially use the term rheumatoid arthritis, but they often mean osteoarthritis," Liebowitz told Fox News Digital. 

"That's a very important distinction. The way you can try to separate that, is nowadays, most people with rheumatoid arthritis are seeing a rheumatologist, and they're on specific immunosuppressant medications."

In contrast, osteoarthritis is a degenerative joint disease caused by the breakdown of cartilage.

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RA can lead to joint deformity and disability if not managed effectively, whereas osteoarthritis may cause similar symptoms of joint stiffness and pain but generally does not lead to systemic complications.

Signs of rheumatoid arthritis are visible indications such as joint swelling, redness and warmth, Liebowitz said.

RA causes the body's immune system to attack the body's own cells, leading to inflammation. This causes the production of excess fluid, which accumulates in the joint cavity and swells.

Inflammation results in increased blood flow to the area, causing the skin to appear red or flushed.

Joint warmth is also a sign of active inflammation. When the immune system attacks, it triggers an inflammatory response, leading to increased blood flow to that area. 

This increased blood flow can cause the joint to feel warm to the touch.

Symptoms that may act as indicators of RA are joint pain, tenderness, swelling or stiffness that lasts for six weeks or longer. Another indicator is feeling stiff for at least 30 minutes in the morning, Liebowitz said.

"Rheumatoid arthritis is when your immune system mistakenly attacks your own body," Liebowitz said. "It causes those symptoms: stiffness, pain, swelling, and it affects specific joints. The most common would be small joints in the hands, like the first and second row of knuckles, wrists, ankles and toes."

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The disease typically affects small joints such as the wrists and those in the hands and feet.

In addition, it often affects the same joints on both sides of the body. If someone with RA experiences pain and swelling in their right wrist, they are likely to feel similar symptoms in their left wrist as well. The symmetry is a common characteristic of the condition.

Many people with RA also experience fatigue or low grade fevers on a regular basis.

While genetics play a role in the development of rheumatoid arthritis, it is not necessarily caused by a genetic mutation, Liebowitz said.

"It's not genetic in that sense," Liebowitz told Fox News Digital. "It varies, but data shows that people with a first-degree relative, meaning a parent or sibling with rheumatoid arthritis, may have about a four times increased risk of developing rheumatoid arthritis themselves."

Although it increases susceptibility, having a genetic predisposition does not guarantee that someone will develop RA.

People who have a family history of the disease but no symptoms or signs do not need to get tested, Liebowitz said.

A doctor with specialized training in treating rheumatoid arthritis, called a rheumatologist, is the best person to make a correct diagnosis using medical history, a physical exam and lab tests.

Rheumatologists are specialized physicians in internal medicine with experience treating various conditions affecting the joints, muscles and bones. This includes inflammatory and autoimmune diseases like RA.

During a physical exam, the doctor will look for joint tenderness, swelling, warmth, painful or limited movement, bumps under the skin or a low-grade fever.

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A rheumatologist would most likely conduct blood tests for inflammation and blood antibodies linked to RA, in addition to taking X-ray scans.

"There is testing that often involves lab work," Liebowitz told Fox News Digital. 

"There are two antibodies. One is called rheumatoid factor, and another one called CCP. That's the type of testing that we would get, as well as two inflammatory markers. One is called ESR, and one is called CRP. Those are some of the basic tests that look specifically for rheumatoid arthritis. We also do X-rays frequently."

Liebowitz said other inflammatory diseases such as psoriatic arthritis and lupus can mimic RA, which is why it is essential to have a trained medical professional differentiate between them.

There is currently no definitive cure for rheumatoid arthritis. As a result, treatment strategies primarily focus on achieving remission.

Liebowitz said he would advise someone who suspects that they might have RA, as well as those who have been diagnosed, to seek care with a rheumatologist.

"Different treatment options include a wide range of medications that have been around for several decades," Liebowitz said. "Starting in the 1980s and '90s, and then more recently, since the early 2000s, biologics have emerged, which are also used to treat rheumatoid arthritis."

The first targeted biologic for RA, which is a drug that targets specific parts of the immune system to treat diseases, was approved by the U.S. Food and Drug Administration in 1998, according to the National Library of Medicine.

Since then, several biologic medications have become commercially available, which have been designed to reduce the signs and symptoms of RA, Liebowitz told Fox News.

Scientists have maintained this momentum, continually working toward treatments and potential cures, fueled by a growing understanding of the disease's complexities.

With each breakthrough, there is renewed optimism for improved outcomes and a better quality of living for those with RA.

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