The erythrocyte sedimentation rate, or ESR for short, is a classic test in laboratory medicine that has been used for over 100 years. It measures how quickly the red blood cells in a tube sink. It may sound unspectacular, but this simple value can tell doctors a lot about whether something is wrong in the body – especially in the case of inflammation, infections or other diseases. In Germany, the ESR is one of the standard tests that can be carried out quickly and inexpensively.

How is the BSG measured?

The erythrocyte sedimentation rate is determined using a blood sample, which is usually taken from a vein. This sample is placed in a thin, upright tube containing a substance called citrate. The citrate prevents the blood from clotting so that the red blood cells can sink freely. You then wait an hour and measure how many millimeters the red blood cells have sunk during this time. The result is given in millimeters per hour (mm/h). There is also a two-hour method, but the one-hour measurement is the most common in Germany.

The method that is most commonly used is called the “Westergren method” – after the Swedish doctor who developed it. It is simple, does not require expensive equipment and still provides reliable indications when something is wrong in the body.

What happens in the blood?

Normally, the red blood cells sink rather slowly because they do not stick together. But when an inflammation or other disease is active in the body, the blood plasma – the liquid part of the blood – changes. It then contains more proteins, so-called acute-phase proteins such as C-reactive protein (CRP) or fibrinogen. These proteins make the red blood cells “stickier”, causing them to pile up into small towers that sink faster. A high ESR often shows that something is going on in the body – but it doesn’t tell you exactly what.

What do the values mean?

The normal values of the ESR depend on age and gender. In men under 50 years of age, it is usually below 15 mm/h, in women below 20 mm/h. It rises slightly with age; in people over 50, up to 20 mm/h (men) or 30 mm/h (women) can still be normal. If the ESR is higher, this could indicate inflammation (e.g. rheumatism), an infection (such as pneumonia) or even cancer. It can also rise during pregnancy or after surgery without there being anything serious behind it.

A very low ESR is rarer and usually less noticeable. However, it can occur if there are problems with the red blood cells, such as in certain anemias.

The importance in laboratory medicine

In laboratory medicine, the ESR is a real all-rounder. It is not a specific test – it does not tell you exactly what disease is present – but it is a great indicator. Doctors often use it as a first step to check whether there is anything wrong in the body. If the ESR is elevated, they usually carry out further tests, such as a blood count analysis or measurement of the CRP, to find the cause. The ESR is an important indicator, particularly in the case of chronic diseases such as rheumatism or unclear symptoms such as fever. It is also used to monitor the progression of a disease: If the ESR drops again, this is often a sign that the inflammation is receding.

What influences the BSG?

The erythrocyte sedimentation rate can be altered by many things. Inflammation is the main reason for an increase, but other factors also play a role. For example, it increases naturally in women during menstruation or pregnancy. Medication such as cortisone can lower it, while a poor diet or being very overweight can increase it. Even the temperature in the laboratory or if the tube is stored at an angle can distort the result – which is why in Germany great care is taken to ensure that everything is standardized.

Limits of the BSG

The ESR has its weaknesses. It is not particularly accurate and can also be elevated in healthy people without there being anything serious behind it. In addition, it sometimes reacts with a delay: an inflammation can subside while the ESR is still high. This is why it is now often used in conjunction with more modern tests such as CRP, which reacts faster and more specifically to inflammation. Nevertheless, the ESR remains a tried and tested tool because it is so simple and inexpensive.

Conclusion

The erythrocyte sedimentation rate is a bit like an early warning system in laboratory medicine. It shows that something is happening in the body without revealing exactly what. In Germany, it is an integral part of many examinations because it is done quickly and often gives the first indication of inflammation or disease. Even if it is no longer the latest test, it remains useful – a simple look into the blood that helps doctors plan the next step.

Editorial office: X-Press Journalistenbüro GbR

Gender note. The personal designations used in this text always refer equally to female, male and diverse persons. Double/triple references and gendered designations are avoided for the sake of better readability ected.