Which of the following lab findings is commonly elevated in rheumatoid arthritis?

In rheumatoid arthritis, it is common to see an elevated erythrocyte sedimentation rate (ESR). The ESR is a non-specific marker of inflammation in the body. In conditions characterized by inflammatory processes, such as rheumatoid arthritis, the body produces specific proteins that increase the tendency of red blood cells to clump together, which increases the rate at which they settle at the bottom of a test tube. An elevated ESR indicates an active inflammatory process, which aligns with the pathophysiology of rheumatoid arthritis, where the immune system attacks the joints, leading to inflammation and pain.

The other options would not be consistent with the typical laboratory findings in rheumatoid arthritis. A low ESR would suggest a lack of inflammation, which is not typical in this disease. High vitamin D levels may not correlate specifically with rheumatoid arthritis and can occur for various reasons. A normal C-reactive protein (CRP) level would indicate that inflammation is not present when, in fact, one would expect to see elevated CRP levels in response to the systemic inflammation associated with rheumatoid arthritis. Thus, elevated ESR is a significant indicator of the inflammatory nature of this autoimmune condition.