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Rheumatoid Arthritis and Psoriatic Arthritis, what are the differences?


I'd like to talk about psoriatic arthritis and the difference between rheumatoid arthritis and psoriatic arthritis. This question comes directly from Nora, so let's dive into it. Please note that this blog post is for educational purposes only and not medical advice, but I hope you'll find it informative and enjoyable.


What are the similarities?

First, let's remember that both psoriatic arthritis and rheumatoid arthritis are two types of inflammatory arthritis. Inflammatory pain has a few distinguishing features: It's usually worse in the morning and improves with exercise. It's also associated with swelling and morning stiffness, lasting for more than 30 minutes. In contrast, mechanical joint pain typically worsens towards the end of the day, isn't associated with significant morning stiffness, and may worsen with exercise.


The similarity between psoriatic arthritis and rheumatoid arthritis often leads to confusion, especially when psoriatic arthritis doesn't present with psoriasis or serological markers of Rheumatoid arthritis. Unlike rheumatoid arthritis, which can be diagnosed through positive rheumatoid factor and CCP antibodies, psoriatic arthritis lacks such serological markers. It's primarily a clinical diagnosis based on symptoms and examination or X-rays findings.


What differentiates RA and Psoriatic arthritis?

So how do we differentiate between rheumatoid arthritis and psoriatic arthritis? The presence of psoriasis is a strong indicator of psoriatic arthritis. However, there are cases where psoriasis is absent, but other symptoms point towards psoriatic arthritis. One key difference is that psoriatic arthritis tends to be asymmetric, meaning it affects one side of the body more than the other. Rheumatoid arthritis, on the other hand (pun not intended), typically affects both sides symmetrically.


Psoriatic arthritis may also cause a condition called dactylitis or "sausage finger," where an entire finger or toe becomes swollen and inflamed. This is different from rheumatoid arthritis, where only the metacarpophalangeal joints (MCPs) and proximal interphalangeal joints (PIPs) of the hands are affected. Additionally, psoriatic arthritis can lead to enthesitis, which is inflammation at tendon insertions. One common location is the Achilles tendon at the back of the foot.


Other symptoms of psoriatic arthritis include inflammatory back pain, which manifests as chronic inflammatory low back pain. Inflammation can also affect the eyes, urinary tract (causing painful urination or blood in urine), and gastrointestinal system (resulting in bloody diarrhea). If you experience any of these symptoms alongside inflammatory arthritis and are seronegative (negative for rheumatoid factor and CCP), it's advisable to get evaluated for psoriatic arthritis.


Psoriasis is usually a clear indicator of psoriatic arthritis, but it's important to thoroughly examine the skin, including less obvious areas like the scalp, ears, belly button, and nails. Nail abnormalities, such as pitting or punctures, are often associated with psoriatic arthritis.


Why is it important to differentiate between Rheumatoid Arthritis and Psoriatic Arthritis?

Proper diagnosis is essential because the treatment approaches for rheumatoid arthritis and psoriatic arthritis differ. While initial treatments may appear similar, long-term management requires distinct strategies to achieve full disease remission. Therefore, it's crucial to receive an accurate diagnosis and start appropriate treatment as soon as possible.


In conclusion:

Both Rheumatoid arthritis and Psoriatic are chronic inflammatory arthritis. While they can appear similar there are clues that can help differentiate both conditions. Treatments are targeting the inflammation. While they may be similar for both conditions, knowing exactly which type of arthritis will allow your rheumatologist to get you to remission faster by getting specific treatment.


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