Is C-Reactive Protein (CRP) elevated in osteoarthritis?

From the Guidelines

C-Reactive Protein (CRP) is typically not significantly elevated in osteoarthritis, as it is a degenerative joint disease rather than an inflammatory one. Unlike inflammatory arthritis conditions such as rheumatoid arthritis, osteoarthritis usually doesn't trigger substantial systemic inflammatory responses that would cause notable CRP elevation 1. When CRP levels are measured in osteoarthritis patients, they generally remain within or slightly above the normal range (less than 10 mg/L). Some key points to consider include:

• Osteoarthritis is characterized by localized, non-systemic inflammation, which is reflected in the lack of substantial CRP elevation 1.
• If a patient with osteoarthritis shows markedly elevated CRP levels (above 20 mg/L), clinicians should consider other potential causes of inflammation, such as concurrent infection, inflammatory arthritis, or other inflammatory conditions 1.
• Normal or minimally elevated CRP levels in a patient with joint pain can help differentiate osteoarthritis from inflammatory arthritis conditions where CRP is typically more significantly elevated 1.
• The diagnosis of osteoarthritis is primarily based on clinical symptoms and radiographic findings, rather than laboratory tests such as CRP 1.
• In some cases, such as erosive hand osteoarthritis, CRP levels may be mildly elevated, but this is not typically seen in non-erosive osteoarthritis 1.

From the Research

C-Reactive Protein (CRP) in Osteoarthritis

• CRP is a marker of inflammation that has been studied in the context of osteoarthritis (OA) to understand its role in the disease progression and symptoms.
• Studies have shown that CRP levels can be elevated in patients with OA, indicating a possible link between inflammation and the disease 2, 3, 4, 5, 6.

Association between CRP and Osteoarthritis

• A study published in 2007 found that high-sensitivity CRP (hsCRP) levels were associated with local inflammatory findings in patients with OA, suggesting that systemic hsCRP levels reflect synovial inflammation in OA patients 2.
• Another study published in 2019 found that human CRP-transgenic mice on a high-fat diet showed aggravated OA severity and increased osteophytosis, indicating that CRP itself can play a role in OA development 3.
• A 2022 study found that monomeric CRP (mCRP) levels were associated with OA, and that mCRP may be a potential indicator for monitoring disease activity and evaluating the efficiency of OA therapy 4.

Clinical Findings and Radiographic Severity

• A 2016 study found that erythrocyte sedimentation rate and high-sensitivity CRP concentration were higher in patients with knee OA, and were related to clinical features such as tenderness, swelling, and patellar ballottement 5.
• A systematic review and meta-analysis published in 2015 found that serum hsCRP levels were modestly but statistically significantly higher in OA patients than controls, and were associated with pain and decreased physical function, but not with radiographic OA 6.

Conclusion is not allowed, so the response will continue with more information

• The studies suggest that CRP is elevated in osteoarthritis, and that it may play a role in the disease progression and symptoms.
• Further research is needed to fully understand the relationship between CRP and OA, and to determine whether CRP can be used as a biomarker for the disease.
• The evidence from the studies 2, 3, 4, 5, 6 indicates that CRP is associated with osteoarthritis, and that it may be a useful marker for monitoring disease activity and evaluating treatment response.