ESR Blood Test: What Your Sed Rate Result Means

ESR is an old, simple blood test that is still widely used. A high result suggests inflammation, but on its own it rarely gives a diagnosis.

Imagine your 70-year-old mother being told her ESR is 35. Her friend’s was 12. Does that mean something is wrong? Not necessarily: ESR rises naturally with age.

What ESR measures

The erythrocyte sedimentation rate measures how fast red blood cells settle at the bottom of a tube in one hour. Inflammation makes them clump and fall faster, giving a higher number.

Typical normal values

• Normal values rise with age and are usually higher in women
• A rough rule of thumb for the upper limit: age divided by 2 for men, and (age + 10) divided by 2 for women, in mm/hr
• Your report will show your lab’s range

What can raise ESR

• Infections
• Inflammatory and autoimmune conditions
• Anaemia and pregnancy
• Some cancers, such as myeloma
• Kidney disease

Very high ESR

Very high ESR, often above 100 mm/hr, can be linked to serious infection, myeloma or conditions such as giant cell arteritis or polymyalgia rheumatica, and needs medical review.

ESR vs CRP

• CRP rises and falls within hours to days
• ESR changes more slowly, over days to weeks
• Doctors often use both together

Lab ranges vary

Reference ranges differ between laboratories and countries, and some use different units. Always compare your result with the range printed on your report and discuss it with your healthcare provider.

Frequently asked questions

Can ESR be low?

Low ESR is rarely a concern, though it can occur with some blood disorders.

Is ESR used to monitor illness?

Yes, for conditions such as polymyalgia rheumatica and some autoimmune diseases.

But what if I have a headache and a high ESR?

If you are over 50 and have a new headache, scalp tenderness, jaw pain when chewing or vision changes, seek urgent medical help, as this can be giant cell arteritis.

Related: Full blood count explained · Normal lab values cheat sheet

Sources: Lab Tests Online UK, NHS, MedlinePlus, British Society for Rheumatology.