Don’t order an erythrocyte sedimentation rate (ESR) to screen asymptomatic patients or as a general test to look for inflammation in patients with undiagnosed conditions.

ESR is a non-specific inflammation marker influenced by various factors including anemia, pregnancy, and smoking. C-reactive protein (CRP) is a less expensive and more sensitive and specific reflection of the acute phase of inflammation, hence should be used for this purpose. In the first 24 hours of a disease process, the CRP will be elevated, while the ESR may be normal. If the source of inflammation is removed, CRP will normalize within a day or so, while ESR will remain elevated for days. Only CRP should be used as a measure of systemic inflammation.
For more information:

Assasi N, Blackhouse G, Campbell K, Hopkins RB, Levine M, Richter T,Budden A. Comparative Value of Erythrocyte Sedimentation Rate (ESR) and C-Reactive Protein (CRP) Testing in Combination Versus Individually for the Diagnosis of Undifferentiated Patients With Suspected Inflammatory Disease or Serious Infection: A Systematic Review and Economic Analysis. Ottawa: Canadian Agency for Drugs and Technologies in Health; 2015 Nov. (CADTH no.140). [Internet].

Brigden ML. Clinical utility of the erythrocyte sedimentation rate. Am Fam Physician. 1999 Oct 1;60(5):1443-50. PMID: 10524488.

Buttgereit F, Dejaco C, Matteson EL, Dasgupta B. Polymyalgia Rheumatica and Giant Cell Arteritis: A Systematic Review. JAMA. 2016 Jun 14;315(22):2442-58. PMID: 27299619.

Harrison M. Erythrocyte sedimentation rate and C-reactive protein. Harrison M1. Aust Prescr. 2015 Jun;38(3):93-4. PMID: 26648629.

Mönig H, Marquardt D, Arendt T and Kloehn S. Limited value of elevated erythrocyte sedimentation rate as an indicator of malignancy. Family Practice 2002 Oct;19(5):436-8. PMID: 12356689.