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No, CRP alone is adequate as the initial test
In a 2006 publication on ESR/CRP, bpacnz recommended that both CRP and ESR should be tested simultaneously
for patients in whom temporal arteritis was suspected.1 However, this is no longer regarded as best practice
and in October 2009, an update was published recommending CRP alone as the initial test.2
The use of ESR in the initial diagnosis of temporal arteritis is largely based on its inclusion in the 1990 American
College of Rheumatology criteria for classification of temporal arteritis.3 However, this reference is now
over 20 years old and the role of ESR as a routine test of the inflammatory response has since been questioned.
ESR and CRP results will sometimes appear discordant when investigating temporal arteritis. In most cases this will
be a normal ESR with an elevated CRP, but an elevated ESR and a normal CRP, while unusual, is also consistent with temporal
arteritis. In a study which examined the sensitivity of CRP and ESR, it was determined that elevated ESR had a sensitivity
of 76% to 86% for temporal arteritis, while an elevated CRP had a sensitivity of 97.5%. When using the criteria of an
elevated ESR or CRP, or both, the sensitivity was 99.2%.4
Applying this to a clinical context, it is considered that the 1.7% increase in sensitivity gained by using both ESR
and CRP compared to the use of CRP alone is not clinically relevant. Any patient with a strong clinical history should
have a temporal artery biopsy or empirical treatment irrespective of the results of laboratory tests.
- bpacnz. CRP vs ESR: Assessing and measuring the inflammatory response. bpacnz, July 2005.
- bpacnz. Report: CRP ESR & Thyroid function testing. bpacnz, October 2009.
- Hunder GG, Bloch DA, Michel BA, et al. The American College of Rheumatology 1990 criteria for the classification
of giant cell arteritis. Arthritis Rheum 1990;33(8):1122-8.
- Parikh M, Miller N, Lee A, et al. Prevalence of a normal C-reactive protein with an elevated erythrocyte sedimentation
rate in biopsy-proven giant cell arteritis. Ophthalmology 2006;113(10):1842-5.