Lab test glossary · Inflammation
ESR (Sed Rate): what it means
Also known as: erythrocyte sedimentation rate, sed rate
ESR is an older, slower-moving marker of inflammation, often read alongside CRP.
What it measures
The erythrocyte sedimentation rate measures how quickly red blood cells settle in a tube over an hour — inflammation makes them clump and fall faster. It's less specific and slower to change than CRP, but the two together give a fuller inflammatory picture.
Typical range
Rises with age; a rough rule of thumb puts the upper normal near age/2 for men and (age+10)/2 for women (mm/hr).
Reference ranges differ between labs and are printed on your own report — always read your result against that range, not a general one.
What a high result can mean
- Infection, inflammation, or autoimmune conditions
- Anemia and older age raise it independently
A high value is a starting point for a conversation, not a diagnosis — many causes are benign or temporary.
What a low result can mean
- Usually not clinically significant
Why the trend matters
Because ESR changes slowly, it's useful for tracking a known inflammatory condition over weeks to months.
When to talk to your doctor
Discuss a markedly elevated ESR with your doctor, especially alongside symptoms or a high CRP.
This page is general education about a common lab test — it isn’t medical advice and can’t interpret your specific result. What a value means depends on your history, symptoms, and the rest of your labs, which is a conversation for you and your clinician.