Symmetric psoriatic arthritis (PsA) is an autoimmune condition that causes symptoms like pain, swelling, and stiffness to joints on both sides of your body. Treatment options range from medication to surgery.

Symmetric PsA is a severe subtype of PsA that affects joints on both sides of your body at the same time. It’s also known as symmetric polyarthritis. “Polyarthritis” means that it affects five or more joints.

Keep reading to learn more about symmetric PsA, including its symptoms, causes, treatment options, and overall outlook.

Types of psoriatic arthritis

There are five main types of PsA:

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The symptoms of symmetric PsA are similar to other forms, with joint stiffness and swelling prominent.

What sets symmetric polyarthritis apart from other PsA subtypes is that the same joints develop symptoms on both sides of your body. For example, this can include joints in both feet, hands, and sides of your knees.

Symmetric PsA also usually affects small joints. Symptoms are most likely to develop within the joints of your hands and feet.

As with other subtypes, symmetric PsA can also cause other symptoms throughout your body. These include:

Symmetric PsA is an autoimmune disease. The underlying inflammation and resulting symptoms develop when your immune system overreacts and mistakenly attacks healthy tissues and joints.

Like other autoimmune conditions, the exact causes are not clear. However, experts think a combination of genetic and environmental factors plays a role.

People who develop symmetric PsA may have asymmetric forms first.

PsA, including symmetric forms, may also occur in people who already have psoriasis, with most cases developing within 7–10 years of the onset of psoriasis. However, not everyone with PsA has psoriasis first.

Risk factors for PsA include:

  • family history of psoriasis, PsA, or any other autoimmune condition
  • smoking
  • obesity
  • serious infections or injuries

And while anyone can develop symmetric PsA, your risk increases with age. Most cases of PsA generally develop in adults over 30 years of age. Females are also more likely to develop this form of PsA than males.

To diagnose symmetric PsA, a healthcare professional might order or perform:

  • a physical exam to check for symptoms
  • a review of your family medical history
  • blood tests to look for inflammatory markers associated with PsA
  • imaging tests, such as X-rays, CT scans, or ultrasounds, which can help detect joint damage

Differential diagnosis

Symmetric PsA can sometimes resemble other inflammatory conditions, like rheumatoid arthritis (RA).

RA also tends to affect your joints symmetrically. Receiving the correct diagnosis is important, as this will influence your treatment plan.

A doctor will carefully distinguish symmetric PsA from RA by considering your symptoms and lab test results. About 80% of people with RA have positive rheumatoid factor (RF) and cyclic citrullinated peptide (CCP) antibodies. People with PsA may or may not have these.

Symmetric vs. asymmetric psoriatic arthritis

Most cases of PsA are asymmetric, meaning it affects joints on one side of your body only. Experts estimate that 60% of PsA cases are asymmetric.

Asymmetric PsA tends to affect fewer than five joints and is more common in people assigned male at birth. It’s also more likely to affect larger joints.

However, most cases of PsA progress to symmetric polyarthritis over time.

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Treatment for symmetric PsA involves a combination of medications that:

  • help reduce underlying inflammation
  • prevent immune system reactivity
  • alleviate your symptoms

Options may include:

Additionally, a doctor may refer you to both physical and occupational therapy. A physical therapist can help teach you flexibility and strengthening exercises, while an occupational therapist will teach you ways to increase mobility, including with assistive devices.

In severe cases of symmetric PsA, a doctor may consider joint replacement surgery. Doctors typically reserve these procedures for when medications fail to prevent further disease progression and specific joints are damaged to the point where the pain and stiffness affect your quality of life.

There’s currently no cure for symmetric PsA or any other PsA subtype. While all types of PsA require prompt treatment, symmetric subtypes are among the most severe and may require aggressive treatment.

The goal of treatment is to help reduce the underlying inflammation while decreasing your symptoms. Treatments can also decrease the risk of progression, which is common in PsA.

Having symmetric PsA may also mean you’re at an increased risk of future complications, especially if the condition is left untreated. As such, a doctor will likely monitor you for:

Symmetric PsA, aka symmetric polyarthritis, is a severe type of PsA that typically involves more than five joints and affects both sides of your body. This can significantly affect your mobility and overall quality of life.

Milder, asymmetric forms of PsA may progress to symmetric PsA.

Treatment for symmetric PsA aims to reduce symptoms and prevent joint damage. While there’s currently no cure for PsA, researchers are continuously discovering more effective diagnostic techniques and treatment options.