Psoriatic arthritis (PsA) is a type of rheumatic or inflammatory arthritis affecting approximately 1.5 million Americans. It affects males and females equally. It is commonly diagnosed in patients with psoriasis, but it is possible to have PsA without the typical skin changes of psoriasis. Up to 30% of individuals with psoriasis develop PsA.

A functional medicine approach to PsA helps address underlying conditions and promote overall well-being and symptom relief.

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What is Psoriatic Arthritis

Psoriatic arthritis (PsA) is an inflammatory arthritis associated with psoriasis. Not everyone with psoriasis will develop PsA, and not everyone with PsA will have psoriasis. Usually, psoriasis appears before PsA, but both can develop simultaneously, or arthritis can appear before psoriasis.

Certain psoriasis skin conditions, such as scalp lesions, nail lesions, and lesions around the anus, are more likely to be associated with developing PsA.

PsA is referred to as seronegative arthritis because, unlike rheumatoid arthritis, there are no definitive antibodies specific to PsA. PsA can be a serious, chronic condition progressing to joint deformity and loss of mobility due to bone and cartilage erosion.

There are different types of PsA and conventional treatments are specific to the type of arthritis.

Different Types of PsA Can Affect:

• Large and small joints
• One to four joints (oligoarticular)
• Five or more joints (polyarticular)
• Tendons and ligaments, especially the bottom of the feet and Achilles’ tendon (enthesitis)
• The spine and neck (spondylitis)
• Fingers and toes (dactylitis)

PsA also puts you at higher risk for conditions that are not typically thought of as being associated with “arthritis.”

Comorbidities Associated with PsA:

• Increased risk of cardiovascular disease (heart attack or stroke)
• Metabolic syndrome
• Diabetes
• Crohn’s disease (a type of inflammatory bowel disease)
• Non-alcoholic fatty liver disease
• Elevated uric acid levels
• Anxiety
• Depression

Psoriatic Arthritis Possible Causes

It’s unclear precisely what causes PsA, but genetics and environmental factors have roles.

Genetics

Some genes related to autoimmunity and inflammation that may be involved are HLA-B27, IL-23A, and TNF.

Environmental Factors

• HIV infection
• Previous infection with Streptococcal bacteria (i.e., group A strep, Strep throat)
• Skin trauma like a sunburn (referred to as the Koebner phenomenon)

Weight

Obesity is a significant risk factor for PsA.  

Altered Gut Flora

Dysbiosis is observed in patients with PsA. Specific gut flora alterations include:

• Fewer Akkermansia, Ruminococcus, and Pseudobutyrivibrio species in patients with PsA
• Less diverse microbial community
• Reduced levels of medium chain fatty acids

Leaky Gut

Altered intestinal permeability or “leaky gut” is associated with psoriasis and systemic inflammation. Some of the leading causes of leaky gut include inflammatory bowel diseases, celiac disease, overuse of alcohol or NSAIDs, food allergies, chemotherapy, and a low-fiber diet.

Psoriatic Arthritis Signs & Symptoms

Since PsA is often seen in individuals who already have psoriasis, an introduction to this condition is warranted.

There are several types of psoriasis, but the most common is plaque psoriasis. It is a scaly plaque that occurs most often on the elbows, knees, and scalp. On average, it takes an estimated 40 to 56 days for your epidermis to completely turn over, but with psoriasis, this skin cell turnover happens in just days and cannot be adequately shed leading to a build up.

Less common forms of psoriasis include guttate, pustular, inverse, and erythrodermic.

The nails can also be affected in psoriasis leading to disorders such as nail pitting, red or white spots in the nail, crumbling nails, and separation of the nail from the underlying skin.

In contrast to the skin manifestations of psoriasis, PsA most commonly affects the following areas:

• fingers and toes
• axial skeleton (spine)
• areas of ligament of tendon attachment to bones and soft tissue (entheses)
• less commonly: knees, ankles, elbows, and shoulders

Common Signs and Symptoms of PsA Include:

• Pain and/or swelling in affected joint(s)
• The distal finger joints are commonly affected
• The spine is commonly affected (especially sacroiliitis)
• Joint pain is often asymmetrical
• Plantar fasciitis or Achilles’ tendon involvement
• Joint stiffness is usually worse in AM and lasts more than 30 minutes
• Stiffness that gets worse with rest and improves with activity
• Fatigue
• Evidence of new bone development in imaging studies

Why Does Psoriatic Arthritis Attack the Skin & Joints?

There is not a clear understanding of exactly why the skin and joints are attacked in psoriasis and PsA. However, there are a variety of immune cells and chemical mediators that are associated with both conditions. These dysregulated cells appear to infiltrate into the skin and joint tissues.

• T cells are increased in the surrounding fluid of joints (synovial fluid) in PsA patients.
• Monocytes are contributors to inflammation in the skin, synovium, and entheses. It has been shown that monocytes from patients with PsA may be more likely to migrate out of blood vessels and into joints, leading to inflammation.
• Inflammatory mediators called cytokines are present in the synovium of patients with PsA.
• Inflammation at the sites where tendons, ligaments, and joint capsules attach to the bone (enthesitis) is also very common in PsA. This phenomenon is thought to be caused by stress forces on the tendon and the surrounding tissues that trigger an inflammatory response in susceptible individuals.

How is Psoriatic Arthritis Diagnosed?

There can be an overlap in signs and symptoms between PsA and other types of arthritis, including gout, rheumatoid arthritis, and osteoarthritis. This can lead to misdiagnosis or delayed diagnosis of PsA, especially when the patient doesn’t have the classic skin or nail changes of psoriasis.

A thorough history, family history, and physical exam are essential.

The “CASPAR criteria” is the most commonly used diagnostic tool for PsA. It is a series of 5 questions; if three or more are positive, a diagnosis of PsA is favored.  

Conventional Lab Tests

There are no specific laboratory tests for PsA, but conventional lab tests help demonstrate the severity of inflammation and response to treatment. These include:

• CBC with differential
• BUN, Cr, uric acid, urinalysis
• ESR & CRP
• RF, anti-CCP, ANA

Although PsA is considered a seronegative type of arthritis, some patients with PsA will have elevated RF, anti-CCP, and ANA antibodies, and this can lead to diagnostic confusion

• HLA-B27 testing
• testing of the synovial joint fluid
• X-rays or other imaging of affected joints

Functional Medicine Lab Tests

A functional medicine approach assesses underlying causes contributing to inflammation and intestinal permeability. These functional medicine tests can be considered:

Food Sensitivity Testing

Testing for food sensitivities ensures that no significant food or dietary triggers are promoting ongoing inflammation and altered intestinal permeability.

Altered Intestinal Permeability

• A comprehensive stool test can identify inflammatory markers in the stool.
• A zonulin marker can help identify leaky gut.
• If your patient prefers a blood test instead of a stool test, consider the Cyrex 2 Array.

Conventional Treatment for Psoriatic Arthritis

Conventional treatments help to control discomfort associated with PsA, minimize joint and tissue damage, and prevent disability. Many of the medications used to suppress the immune system have significant side effects, so be sure to discuss your personal medical history with your doctor before starting a new medication.

Conventional Treatments Include:

• Nonsteroidal anti-inflammatory drugs or NSAIDs (like ibuprofen or diclofenac). These help reduce inflammation and ease discomfort, but they have FDA black box warnings for being linked with heart attack, stroke, gastrointestinal bleeding, ulcerations, and perforation. These medications can also affect your kidneys.
• Immunosuppressive medications called disease-modifying anti-rheumatic drugs or DMARDs (like methotrexate) reduce inflammation and are used if NSAIDs are ineffective.
• Biologic DMARDs (like TNF inhibitors) reduce inflammation and are tried when medications like methotrexate are ineffective.
• Glucocorticoids (like prednisone or dexamethasone) may have a role in short-term use when other medications are not working. They are not commonly used because of their negative long-term side effects and the possible worsening of skin psoriasis.

Natural Remedies for Psoriatic Arthritis

Nutrition for Psoriatic Arthritis

In general, weight loss is beneficial for PsA as even a 5% reduction in weight can provide symptom relief. Another benefit of weight loss is that medications for psoriasis or PsA appear to work more effectively with weight reduction.

There is no specific diet that has been tested for PsA. However, it is recommended that you work with your doctor to rule out food allergies or sensitivities that can contribute to inflammation or leaky gut.

Eliminating pro-inflammatory foods and increasing the intake of anti-inflammatory foods are likely beneficial for symptom relief of PsA.

Pro-Inflammatory Foods to Avoid:

• Processed foods (usually pre-packaged and have multiple ingredients on the label)
• Fried foods
• Soda, including artificially sweetened beverages
• Processed seed oils, margarine, trans fats, hydrogenated oils
• Processed meats
• Dairy products
• Nightshade vegetables (tomatoes, eggplant, peppers, etc.) if you are sensitive or allergic

Anti-Inflammatory Foods to Include:

• Berries
• Citrus fruits and apples
• Dark leafy green vegetables like kale, spinach, dark lettuce, broccoli greens
• Nuts and seeds (especially walnuts, chia seeds, and hemp seeds)
• Whole grains
• Beans

Dead Sea Salt Therapy

Studies have reported that soaking in the Dead Sea (balneotherapy) is very effective for psoriasis and PsA.

Turmeric

Human immune and inflammatory cells were studied, and it was found that curcumin significantly decreased the production of inflammatory chemicals in patients with PsA and psoriasis.

Omega-3 Fatty Acids

Patients with PsA who were treated with omega-3 fatty acids used significantly less NSAID and acetaminophen than control groups.

Light Therapy for Psoriatic Arthritis

Studies show that Ultraviolet (UV) light effectively treats the skin symptoms of psoriasis and arthritis.

Two types of UV light are used to treat psoriasis: UVA and UVB.

According to The Arthritis Foundation, sunlight is the easiest way to get UV exposure. It’s recommended to use broad-spectrum sunscreen (SPF 15 or higher) and get 20 to 30 minutes of sun exposure around noon daily.

If you don’t live in a sunny climate or can’t get daily exposure to the natural sun, UVB light therapy at a doctor’s office or clinic is excellent. It is the gold standard for psoriasis and PsA treatment.

Tanning beds are not a substitute for natural sunlight or targeted PUVA or UVB therapies from a doctor’s office. Artificial tanning beds can prematurely age skin and have been linked with skin cancer, including melanoma.

Summary

Psoriatic arthritis is an autoimmune inflammatory arthritis caused by genetics and environmental factors. It is more commonly seen in people who already have a diagnosis of psoriasis. Joints, tendons, and ligaments can be affected in PsA, resulting in mild to severe pain that can be progressive and disabling.

PsA is also associated with various severe health conditions, such as cardiovascular disease, obesity, diabetes, depression, and anxiety.

A functional medicine approach can evaluate possible root causes of inflammation, dysbiosis, and immune system dysfunction.

Lifestyle changes, including weight loss and anti-inflammatory foods, can facilitate a better quality of life and symptom relief. These lifestyle changes will also help with cardiovascular health, obesity, and diabetes, comorbidities seen with PsA.

Specific supplements like turmeric and omega-3 fatty acids can also improve PsA symptoms.