ESR Test (Erythrocyte Sedimentation Rate)

What is an ESR test?

ESR (Erythrocyte Sedimentation Rate) measures how fast red blood cells fall to the bottom of a test tube in one hour. When inflammation or infection is present, proteins in the blood cause red cells to clump together and sink faster. ESR is one of the oldest blood tests and is still widely used because it's cheap, simple and a good screening tool for hidden disease. However, ESR alone cannot diagnose a condition: it only signals that something needs further investigation.

ESR Normal Range (Westergren Method)

What does HIGH ESR mean?

What does a NORMAL ESR mean with symptoms?

ESR vs CRP: which is better?

Questions to ask your doctor

• Should I also check CRP and other inflammatory markers?
• Do I need a chest X-ray to rule out TB?
• Is this ESR level consistent with my symptoms?
• How often should I monitor ESR for my condition?

References

The clinical information on this page is drawn from peer-reviewed sources indexed by the US National Library of Medicine. Links go to the source so you can read it yourself.

1. Erythrocyte Sedimentation Rate. In: StatPearls. Treasure Island (FL): StatPearls Publishing. NCBI Bookshelf NBK557485

References

Sources cited on this page. PubMed links open the original abstract.

1. Sox HC, Liang MH. The erythrocyte sedimentation rate: guidelines for rational use. Ann Intern Med. 1986;104(4):515–523. PMID 3518393 · doi:10.7326/0003-4819-104-4-515

How ESR is measured and why it rises

The erythrocyte sedimentation rate (ESR) measures how quickly red blood cells settle to the bottom of a vertical tube of blood over one hour. Normally, red cells fall slowly because they carry negative surface charges that cause mutual repulsion. In inflammation, the liver produces acute phase proteins – particularly fibrinogen, α-2 macroglobulin, and immunoglobulins – that coat red cells and neutralise their negative charges. The cells then aggregate into "rouleaux" (stacks like coins), become heavier, and settle faster.

Normal ESR: approximately 0–15 mm/hr in men and 0–20 mm/hr in women (both ranges increase with age – a rough rule of thumb: ESR up to age ÷ 2 in men, age ÷ 2 + 5 in women). ESR above 100 mm/hr is a "panic value" that demands urgent investigation.

ESR versus CRP – when to use each

Both ESR and CRP are non-specific inflammatory markers, but they behave differently and complement each other:

• Speed of response: CRP rises within 4–12 hours of an inflammatory stimulus; ESR lags by 24–48 hours. CRP is a better marker of acute illness; ESR is more useful for monitoring prolonged inflammatory conditions.
• Return to normal: CRP normalises within days of resolving inflammation; ESR can remain elevated for weeks even after the stimulus resolves. ESR may mislead by suggesting ongoing disease when the inflammation has cleared.
• Clinical uses of ESR: Particularly elevated in: multiple myeloma (ESR often above 100 – paraprotein directly increases rouleaux formation); giant cell arteritis / polymyalgia rheumatica (ESR above 50, often above 100 – an ESR above 40 in the clinical context is part of the diagnostic criteria); chronic infections (TB, subacute bacterial endocarditis); and autoimmune diseases (RA, SLE, Sjögren's).
• Clinical uses of CRP: Better for monitoring treatment response in RA (falls with effective therapy); guides antibiotic decisions in pneumonia (CRP above 100 mg/L supports bacterial cause); used alongside Wells score and D-dimer in DVT/PE workup.

Causes of a very high ESR (above 100 mm/hr)

An ESR above 100 mm/hr has a specific differential diagnosis that should always be considered and investigated:

• Multiple myeloma or Waldenström's macroglobulinaemia (paraprotein)
• Giant cell arteritis / polymyalgia rheumatica
• Active systemic lupus erythematosus
• Severe bacterial infection or sepsis
• Active tuberculosis
• Nephrotic syndrome (low albumin, high fibrinogen)
• Metastatic malignancy