To rule out rheumatoid arthritis, most important among the followings is?
## Core Concept
Rheumatoid arthritis (RA) is a chronic autoimmune disorder characterized by symmetric polyarthritis, primarily affecting the hands and feet. The diagnosis of RA involves a combination of clinical presentation, laboratory tests, and imaging studies. To rule out RA, it is essential to understand the diagnostic criteria and the role of various tests.
## Why the Correct Answer is Right
The correct answer, Rheumatoid Factor (RF) and Anti-Citrullinated Protein Antibody (Anti-CCP), are crucial in the diagnosis of RA. RF is an antibody directed against the Fc portion of IgG, and Anti-CCP antibodies are directed against citrullinated peptides. Both are included in the 2010 ACR/EULAR classification criteria for RA. A negative result for both RF and Anti-CCP does not entirely rule out RA, but testing for these antibodies helps in diagnosing and differentiating RA from other forms of arthritis.
## Why Each Wrong Option is Incorrect
* **Option A:** This option is not specified, but typically, tests like ESR and CRP are markers of inflammation and are not specific for RA.
* **Option B:** This option is also not specified, but imaging studies like X-rays can show joint damage but are not used to rule out RA initially.
* **Option C:** Similarly, this option is unspecified but could relate to other diagnostic tests or clinical assessments that are not as directly relevant to ruling out RA as RF and Anti-CCP.
## Clinical Pearl / High-Yield Fact
A key clinical pearl is that while RF and Anti-CCP are highly specific for RA, they are not highly sensitive. This means some patients with early RA may test negative for these antibodies. A significant clinical correlation with symmetric joint involvement and other diagnostic criteria is essential.
## Correct Answer Line
**Correct Answer: D.**