A new study has found that erythrocyte sedimentation rate (ESR) samples measured by photometric rheology on innovative new analysers remained accurate for up to 28 hours at room temperature and 48 hours refrigerated, seven times longer than the traditional Westergren method's four-hour room-temperature limit.
For a hundred years, a sample to be tested for ESR - relied upon by doctors to diagnose and monitor infections, autoimmune conditions and other diseases – had to be tested or refrigerated within four hours for its result to be trusted. A new peer-reviewed study published in Diagnostics says that deadline belongs to the past.
The study found that ESR samples measured by photometric rheology on ALCOR Scientific's iSED analysers remained accurate for up to 28 hours at room temperature and 48 hours refrigerated. As clinical laboratories contend with scattered blood collection sites, longer courier routes and staffing shortages, the extended sample stability could deliver immediate benefits to laboratories and the patients they serve.
ESR is one of the oldest tests in medicine, and one of the most widely ordered, with millions performed every year. It's a fast and affordable marker of inflammation that helps detect and monitor a range of conditions, from infections and autoimmune diseases like rheumatoid arthritis to inflammatory conditions like giant cell arteritis, as well as certain cancers. Unlike tests that measure a specific molecule, ESR measures a behaviour: how quickly red blood cells aggregate and settle in a tube, which makes it acutely vulnerable to time and temperature.
But with laboratories consolidating into centralised, high-volume centres, they're navigating growing blood collection sites and staffing shortages. Between the needle and the analyser sits a courier network that batches specimens onto multi-stop routes, often carrying them for hours in vehicles with no meaningful temperature control. Meeting a strict four-hour clock across that chain is often impossible. Worse, the failure is invisible because a degraded sample doesn't arrive flagged. It arrives looking perfectly normal, and its result gets reported and acted on like any other.
The iSED analyser takes a fundamentally different approach to ESR testing. Using photometric rheology technology, it optically captures red blood cell aggregation, the earliest and most critical step of erythrocyte sedimentation, inside a temperature-controlled flow cell, generating a result in less than 20 seconds. Because it reads the very beginning of the aggregation process in a controlled environment, the iSED analyser is largely insulated from the time-sensitive changes that undermine traditional readings, extending sample stability seven times longer than traditional testing.
Jim Post, CEO at Alcor Scientific commented: "For decades, labs have been forced to build their entire ESR workflow around limited sample stability. Extending room temperature stability by an additional 24 hours is a game changer, not only improving logistics but truly improving patient care by ensuring reliable results. Giving labs a full day of reliable stability isn't a convenience. It's better medicine."
- Koshy T, Lamazares Y, Evans S, Jortani S. Measuring Erythrocyte Sedimentation Rate Using Photometric Rheology Technology Demonstrates Superior Sample Stability as Compared to the Westergren Method. Diagnostics (Basel). 2026;16(16):2648. doi:10.3390/diagnostics16162648