Erythrocyte sedimentation rate

The erythrocyte sedimentation rate, also known as ESR, is one of the oldest and most common blood tests. It shows whether inflammation is present in the body, so doctors request it for persistent fatigue, fever, joint pain or monitoring rheumatic disease. It does not show where inflammation is or what caused it, but is a useful guide to further tests.

Who is this test for

• people with persistent fatigue, weight loss or fever of unknown cause;
• for pain, swelling or morning stiffness of joints and muscles, particularly the shoulders and hips in older people;
• for monitoring rheumatoid arthritis, polymyalgia rheumatica and other long-term inflammatory diseases;
• people over 50 with a new headache in the temples, particularly with pain when chewing or visual problems, who should contact a doctor the same day;
• during a comprehensive or preventive check-up, alongside a complete blood count and CRP.

What the test reveals

When blood stands undisturbed, red blood cells (erythrocytes) slowly sink. ESR measures how many millimetres they fall in one hour (mm/h). In inflammation, blood contains more fibrinogen and immunoglobulins, so red cells form stacks like piled coins that sink faster. This involves cells stacking together, not blood clotting.

A raised ESR means there is inflammation, infection or another change in blood proteins. ESR rises and falls more slowly than CRP, making it more useful in long-term inflammatory disease than acute infection. Read how inflammatory markers complement each other in the article on inflammatory parameters.

The test and preparation

The sample is venous blood, and collection takes a few minutes. Fasting is not required for ESR alone. If glucose or blood lipids are tested from the same sample, come fasting in the morning. Tell your doctor if you are pregnant or have recently had an infection, because these increase ESR.

What your results mean

• Normal ESR means there are no signs of more pronounced inflammation, but does not exclude disease. If symptoms persist, the doctor continues investigations.
• Mildly raised ESR often has no serious cause. It is higher in women and older people, during pregnancy, with anaemia and kidney disease, and after a recent infection. The doctor may repeat it or compare it with CRP.
• Markedly raised ESR suggests inflammation, infection or rheumatic disease. Values above 100 mm/h usually have a more serious cause, such as a severe infection, inflammatory disease or, less commonly, a blood disease such as multiple myeloma, and require investigation without delay.
• Low ESR rarely has particular significance. It may occur when the red blood cell count is high.

The reference interval depends on sex and age and is printed on the report. A doctor interprets the result alongside symptoms, examination, CRP and a complete blood count.

How to arrange testing

You can come for blood collection without an appointment or referral at one of our branches throughout Croatia (listed on the Contactpage). Prices for all tests and panels are listed in the price list. ESR is part of the Extended Preventive Panel, which also includes a complete blood count, glucose, blood lipids and liver and kidney tests.

Frequently asked questions

What is the difference between ESR and CRP?

Both tests show inflammation. CRP rises within a few hours and falls quickly when inflammation resolves, so it reflects acute changes better. ESR changes more slowly and is used more in long-term inflammatory diseases. Doctors often request them together.

Can ESR be raised without disease?

Yes. It is naturally higher in women and rises with age, and pregnancy and anaemia also increase it. A mildly raised ESR in someone without symptoms is therefore interpreted cautiously.

How long does ESR remain raised after an infection?

ESR normalises slowly and may remain raised for several weeks after you feel well. If tested soon after an illness, a doctor may repeat it later.

Do I need to fast for ESR?

No. Come fasting only if tests requiring it, such as glucose or lipids, are performed from the same blood collection.