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The History of ESR

The observation that blood cells settle at different rates depending on a person's health dates back centuries, but the modern test traces to Swedish physiologist Robin Fahraeus, who in 1918 systematically demonstrated that red blood cells settled unusually fast in pregnant women and in patients with certain diseases, establishing the underlying scientific principle. His countryman Alf Westergren refined this observation into a standardized, reproducible clinical procedure in 1921, diluting blood with an anticoagulant and measuring how far red cells fell in a vertical tube over exactly one hour, a method that still bears his name today. The Westergren method spread rapidly through European and American laboratories over the following decades and, despite the arrival of newer inflammatory markers, remains one of the oldest continuously used blood tests still ordered routinely in modern medicine.

What ESR Actually Is

Erythrocyte sedimentation rate measures how quickly red blood cells settle to the bottom of a vertical tube of blood over one hour, a simple physical phenomenon that speeds up considerably whenever inflammation is present anywhere in the body. Inflammation causes the liver to produce more fibrinogen and other proteins, which coat red blood cells and cause them to clump together into stacked formations called rouleaux; these heavier clumps fall faster than individual cells would on their own, so a higher ESR simply reflects that this clumping is occurring due to inflammatory activity. Because ESR responds to so many different inflammatory conditions rather than any single specific disease, it functions as a broad, nonspecific screening tool that must always be interpreted together with symptoms and other more targeted laboratory findings.

How ESR Is Measured

The classic Westergren method draws blood into a long, thin, calibrated glass tube held perfectly vertical, and a laboratory technician simply reads off the distance the red blood cells have fallen after exactly sixty minutes have elapsed, reported in millimeters per hour. Modern automated ESR analyzers now use optical or centrifugal methods to estimate the same sedimentation behavior in just minutes rather than a full hour, though many laboratories still validate these faster instruments directly against the traditional Westergren reference method to ensure consistent accuracy. Because temperature, tube tilt, and even how long blood sits before testing can all meaningfully affect the result, careful, standardized sample handling remains essential for reliable ESR reporting in any clinical laboratory setting.

Scientists Behind the Science

Robin Fahraeus deserves credit for the original 1918 scientific insight connecting sedimentation behavior to underlying disease states, a discovery he made while investigating why pregnant women's blood behaved so differently under the microscope than that of other patients. Alf Westergren then transformed that raw scientific observation into the practical, standardized clinical test still used worldwide today, publishing his refined dilution and tube-based method in 1921 in a form so effective that it required remarkably little modification over the following century of continuous clinical use. Together, this Swedish duo gave medicine one of its earliest reliable inflammatory markers, a genuinely humble glass-tube test that nonetheless remains clinically relevant even now, in an age of far more sophisticated and expensive laboratory technology.