Erythrocyte Sedimentation Rate (ESR)

One of the oldest and most frequently requested blood tests is ESR. It has not changed fundamentally in the way it is carried out since Westergren described it in 1921. In 2011, the International Council for Standardization in Hematology (ICSH) and the Clinical and Laboratory Standards Institute (CLSI) defined the Reference Method for ESR to be the Westergren Method; the Gold Standard. The objective of ESR testing is to measure inflammatory state. The Westergren Method measures both infections related to infectious diseases and chronic inflammatory conditions. In addition to being very reliable, the Westergren Sedimentation Method is also amongst the cheapest laboratory tests available.

Wikipedia ESR