ESR and CRP in one minute
| Test | What it is | Behaviour |
|---|---|---|
| ESR | How fast red blood cells settle in a tube | Rises slowly and falls slowly; affected by age, anaemia, pregnancy and kidney disease |
| CRP | A protein made by the liver during inflammation | Rises within hours and falls within days — good for tracking flares and infections |
Check the unit on your CRP report. 10 mg/L and 10 mg/dL are very different — the second is ten times higher. The lab unit converter helps.
Common causes of a raised ESR or CRP
- Infections — by far the most common cause of a high CRP
- Inflammatory arthritis, polymyalgia rheumatica, vasculitis
- Anaemia, kidney disease, pregnancy and older age (ESR especially)
- Recent injury or surgery
- Obesity (mild rises)
- Some cancers (less commonly)
A very high ESR (above about 100 mm/hr) has a narrower list of causes and should always be explained.
Normal results don't rule out arthritis
Some people with active rheumatoid arthritis, psoriatic arthritis or ankylosing spondylitis have normal ESR and CRP. Symptoms and examination come first.
What to do next
- Raised with joint swelling, morning stiffness, or shoulder and hip stiffness after 50? See a rheumatologist.
- Raised with fever? Infection needs to be excluded first.
- Mildly raised, no symptoms? Often repeated after a few weeks; usually settles.
Common questions
What is a normal ESR?+
It varies by age and sex. A rough upper limit is age ÷ 2 for men and (age + 10) ÷ 2 for women, in mm/hr. Your lab's reference range applies.
Can stress cause a high ESR?+
Not directly. ESR is raised by inflammation, infection, anaemia, pregnancy, kidney disease and older age.
Is CRP better than ESR?+
They complement each other. CRP changes quickly and is better for tracking infections and flares; ESR changes slowly and is influenced by more factors.
Have a result you're worried about?
Bring the report — results only make sense alongside your symptoms and an examination. Walk-in, no appointment needed.
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