Contact with glass interferes with the Erythrocyte Sedimentation Rate (ESR)

The sedimentation rate (sed rate), also called, the Erythrocyte Sedimentation Rate (ESR) is a blood test for inflammation in the body. If it is elevated, then there is an inflammatory process in the body which can be monitored. The test is broad and non-specific; however, it may determine the effectiveness of therapy for the inflammatory condition. We performed studies on human citrated whole blood by adding 100 microlitres of 1% of MethylCellulose to each of glass and plastic tubes with the blood. The samples (n=12) were incubated at 37° for 10 minutes. Later, the blood from each of the tubes were placed in pipettes, sealed and left undisturbed for an hour. The ESR was measured, and it was found that the sedimentation rate of the blood in plastic settled at a higher rate than the one in glass.