Final answer:
Rheumatoid arthritis (RA) is a systemic autoimmune disease causing chronic inflammation, joint pain, erosions, and systemic complications. It's diagnosed through a combination of symptoms, blood tests, and imaging. While the exact cause is unknown, it involves a hypersensitivity reaction and chronic inflammation.
Step-by-step explanation:
Rheumatoid Arthritis
Rheumatoid arthritis (RA) is a chronic systemic autoimmune disorder that predominantly impacts synovial joints. The characteristic symptoms of RA include joint swelling, stiffness, and pain. Although it's clear that RA is an autoimmune condition, whereby one's immune system mistakenly targets healthy tissue, the precise cause of RA is still a mystery. Over time, the inflammatory process in RA can lead to erosions – the wearing away of bones within the joint – as well as a narrow joint space observable via diagnostic imaging. Symptoms, blood tests measuring levels of rheumatoid factor (RF) and antibodies such as anti-CCP, along with imaging studies like X-rays, ultrasound, and MRI, are used for diagnosis. RA is systemic since it can cause muscle loss and fat gain, enhancing atherosclerosis risks, thus it doesn't only affect joints but can have widespread bodily effects.
Known triggers for RA include genetic predispositions and environmental factors, but detailed causes remain to be fully understood. It is a type III hypersensitivity reaction involving CD4 T cells that release inflammatory cytokines such as IL-1, IL-6, and TNF-α. This contributes to the chronic inflammation, systemic symptoms, and the joint damage that RA is known for. Treatment focuses on symptom relief, using a range of methods from medication to surgery, since RA is incurable.