Photometric Rheology: A New Gold Standard for ESR?

Richa Bedi, PhD, MHA, MS, MLT(ASCP) and Jane M. Caldwell, PhD

Introduction

Erythrocyte Sedimentation Rate (ESR) is one of the most well-known and widely used laboratory tests in the world. This inexpensive, nonspecific test allows for the assessment of inflammation in the body and is routinely used to screen and monitor patients with subclinical, acute, and chronic inflammatory diseases. Although ESR remains a clinically relevant indicator, its measurement was usually laborious and required strict limitations on sample stability (no more than 4 hours at room temperature).

Evolution of ESR

Westergren's reference method, developed in 1921, is based on complete sedimentation of erythrocytes within 60 minutes. New automated measurement technologies use photometric rheology. This is a unique method that evaluates only the aggregation of erythrocytes (the formation of "coin columns"), which represents the first phase of the sedimentation process.

Since photometric rheology only evaluates aggregation, it is independent of many physical factors (time, ambient temperature, table vibration, tube angle) that significantly distort the results of the manual method.

Integrity and reliability of the sample

A 2025 study initiated by ALCOR Scientific evaluated sample stability in the iSED series ESR photometric rheology analyzers. The results showed the stability of measurements up to 28 hours at room temperature and up to 48 hours under cooling, which is almost 7 times longer than for the Westergren method. This greatly simplifies the transportation of samples to the central laboratory and prevents repeated blood sampling.

Transformation of ESR for modern laboratories

In conditions of a significant shortage of personnel in medical laboratories, the automation of ESR is critical. iSED® ESR analyzers from ALCOR® Scientific reduce laboratory technician hands-on time by 96% and total analysis time by 87% (only 10 minutes for 20 samples versus 81.9 minutes for the manual method). The devices work directly with primary EDTA tubes, eliminating the need to open the lids and minimizing biological risks to personnel.

Conclusion: advantages of the iSED platform

• Elimination of environmental exposure: the analysis is performed in a closed, thermostatic environment at 37°C.
• Automation: the entire process is controlled automatically, eliminating the subjectivity of the operator.
• Safety: work without uncorking the tubes and without additional disposable capillaries.

Educational support for this article was provided by ALCOR Scientific.