ESR (erythrocyte sedimentation rate): what it is, what it tells you and when it’s tested

ESR measures how fast your red blood cells settle to the bottom of a tube in one hour. With inflammation, certain proteins in your blood rise and make them fall faster. That is why a high ESR is a sign of inflammation, but it does not say where it is or why.

When it’s tested

Doctors order it when they are looking for inflammation: a fever with no clear cause, joint pain, tiredness and weight loss. It is most useful for a few specific conditions, such as polymyalgia rheumatica and giant cell arteritis, and for following them over time.

It is not a good test for people who feel well. It rises with age, anaemia and pregnancy, and a slightly high ESR without symptoms rarely leads to a diagnosis.

That is why Rosa does not test it. Instead it measures high-sensitivity CRP, which picks up inflammation more precisely and more quickly, along with white blood cells and haemoglobin.

What it tells you, and what it does not

If it is high, there is probably inflammation somewhere in your body. It can come from an infection, an autoimmune disease, a kidney problem or, less often, a cancer.

It does not say where the inflammation is or what is causing it. It also changes slowly: it rises and falls over days or weeks.

If it is normal, significant inflammation is less likely, but not ruled out.

That is why it is read together with other tests:

• High-sensitivity CRP: It picks up inflammation sooner and more precisely
• Haemoglobin: Anaemia alone raises the ESR
• White blood cells: If they are high, an infection is more likely
• Fibrinogen: It is one of the proteins that push it up

Normal ESR levels

The lab decides what is normal. Many lab reports give up to 15 mm/h for men and up to 20 for women, under age 50.

After 50 the limit goes up: many reports give up to 20 mm/h for men and up to 30 for women. A rule of thumb for older people: the limit for men is about their age divided by two; for women, their age plus ten, divided by two.

It is a little higher in women, and it rises in pregnancy.

What your result means

Find the row for your result, in mm/h. Which values need a doctor? Above the limit on your report; from 50, soon.

• Women: up to 20, Men: up to 15: Normal. No sign of significant inflammation, at any age. Nothing to do.
• Women: above 20, up to 30, Men: above 15, up to 20: Slightly high. Before 50 it is slightly high. After 50, many lab reports still call it normal. Anaemia and pregnancy push it up too. If you feel well, your doctor usually just rechecks it later.
• Women: above 30, below 50, Men: above 20, below 50: High. Often there is inflammation or an infection, sometimes one that has already passed. In older people it can rise without any disease. Show your report to your doctor. They usually look at CRP too.
• 50 to 100: Very high. There is usually a cause to find: an infection, an inflammatory disease, sometimes something else. Talk to your doctor soon.
• Above 100: Extremely high. There is almost always a cause: an infection, kidney disease, an inflammatory disease or a cancer. See your doctor within a few days.

If your ESR is high or low

• High ESR: Usually there is inflammation or an infection. How high it is, and whether you have symptoms, both matter.
• Low ESR: Almost never a problem. It happens with many red blood cells or little fibrinogen.

What can skew the result

A few things change it without any disease.

• Age: It creeps up over the years. A normal value at 70 can be high at 30.
• Anaemia: With fewer red cells, the ones left settle faster. ESR goes up.
• Pregnancy: ESR rises on its own in pregnancy. It usually means nothing.
• A recent infection: After flu or a cold it can stay high for a few weeks, even when you feel well.

When to worry

Talk to your doctor if:

• Your ESR is above the limit on your report and you have symptoms, such as fever, pain or weight loss.
• It is 50 or more: see your doctor soon, the cause needs to be found.
• It stays high over several checks, even if you feel well.
• You are over 50 and have a new headache, pain at your temple or in your jaw when you chew: see your doctor the same day.
• You see double or lose your sight, even briefly: call 112 or go to the emergency department.

Frequently asked questions

What are normal ESR levels? Many lab reports give up to 15 mm/h for men and up to 20 for women, under age 50. After 50, up to 20 and up to 30. The range on your own report is what counts.

What is the difference between ESR and CRP? Both show whether there is inflammation. CRP rises and falls quickly, within a day or two. ESR is slower and is affected by age, anaemia and pregnancy. That is why doctors often look at both.

Do I need to fast for an ESR test? Usually not. If you have other tests at the same time, such as glucose or cholesterol, follow the instructions for those.

Does a high ESR mean cancer? Rarely. The most common causes are infections and inflammation. A very high value, above 100, always needs an explanation, and your doctor looks for the cause calmly and with the right tests.

Does Rosa test ESR? No. Rosa measures high-sensitivity CRP, white blood cells and haemoglobin, which say a lot about inflammation and anaemia. If your doctor wants an ESR, they order it separately.

Sources

• Brigden, clinical utility of the erythrocyte sedimentation rate. American Family Physician, 1999. PMID 10524488
• Miller and colleagues, simple rule for calculating normal erythrocyte sedimentation rate. British Medical Journal, 1983. PMID 6402065
• Hunder and colleagues, the American College of Rheumatology 1990 criteria for the classification of giant cell arteritis. Arthritis and Rheumatism, 1990. PMID 2202311
• Fincher and Page, clinical significance of extreme elevation of the erythrocyte sedimentation rate. Archives of Internal Medicine, 1986. PMID 3729639