C-reactive protein and erythrocyte sedimentation rate: Continuing role for erythrocyte sedimentation rate

Background: Erythrocyte Sedimentation Rate (ESR) and C-reactive protein (CRP) tests are often done to detect or monitor patients with suspected inflammatory disorders. The objective of the study was to ascertain if the manual ESR test added value to the information available from automated CRP results alone. Methods: In this retrospective, observational study at a safety-net hospital, the ESR and CRP values were compared in 4527 instances when both tests were done. In 150 instances, involving 97 patients; when ESR was >60 mm/hr and CRP was ≤1.0 mg/dL, the medical records were reviewed to discern the cause of disparity between the ESR and CRP results and to assess the utility of continued use of the ESR test. Results: Review of medical records did not reveal an explanation for elevated ESR in 20 patients with normal CRP results. In the remaining 77 (79%) patients, an inflammatory disorder was noted despite a normal CRP value; in 27 (28%) patients, the disorder was osteomyelitis. Presence of skin necrosis was also a prominent factor in the discrepant results. Conclusions: ESR has value in detecting inflammatory disorders that may not be obvious by clinical examination or CRP results. ESR has a particularly useful role in patients with suspected bone lesions and osteomyelitis.