How do I interpret an elevated serum C-reactive protein (CRP) and normal erythrocyte sedimentation rate (ESR) or vice-versa?

Discordance between serum CRP and ESR is not uncommon (1,2). This phenomenon may be due to a variety of factors including the fact that the kinetics of these two tests is quite different, as discussed under “Should I order C-reactive protein (CRP) or erythrocyte sedimentation (ESR) on patients suspected of having a new infection?” in this blog. In a study of CRP/ESR discordance (defined as results differing by 2 or 3 quartiles) in adults, a high CRP/low ESR profile was more likely to be associated with  urinary, GI, blood stream, and pulmonary infections, myocardial infarction, and venous thromboembolism and less likely to be associated with bone and joint infections (1). In the same study, a high ESR/low CRP was associated with connective tissue diseases, such as systemic lupus erythematosus and strokes (1).

1. Feldman M, Aziz B, Kang GN, et al. C-reactive protein and erythrocyte sedimentation rate discordance: frequency and causes in adults. Translational Research 2013;161:37-43.

2. Colombet I, Pouchot J, Kronz V. Agreement between erythrocyte sedimentation rate and C-reactive protein in hospital practice. Am J Med 2010;123:864.e7-863.e13.

How do I interpret an elevated serum C-reactive protein (CRP) and normal erythrocyte sedimentation rate (ESR) or vice-versa?

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