Test

C-Reactive Protein / CRP Test

CRP test explained: what C-reactive protein measures, normal vs high levels, hs-CRP for heart risk, when to get tested, and online booking.

Key Takeaways

What you need to know at a glance

CRP is a non-specific inflammation marker that rises rapidly with infection, injury, or autoimmune disease.
hs-CRP (high-sensitivity) is used to assess cardiovascular risk — above 3.0 mg/L indicates high risk.
No fasting is required for standard CRP; hs-CRP may need a fasting sample.
CRP must be interpreted in clinical context — it shows inflammation exists but not the specific cause.
Full Article

What It Measures#

The CRP (C-Reactive Protein) test measures the level of C-reactive protein in your blood — a protein produced by the liver in response to inflammation. CRP rises rapidly within hours of an infection, injury, or inflammatory process and drops quickly once the cause resolves.

There are two versions of the test:

  • Standard CRP — measures higher levels of inflammation; used to detect and monitor infections, autoimmune conditions, and acute inflammatory diseases.
  • hs-CRP (High-Sensitivity CRP) — detects much lower levels; primarily used to assess cardiovascular risk. Even mildly elevated hs-CRP is associated with increased risk of heart attack and stroke.

CRP is a non-specific marker — it tells you that inflammation exists but does not pinpoint the cause. It must be interpreted alongside symptoms and other investigations.

Who Should Get Tested#

  • Anyone with signs of infection: fever, pain, swelling, redness.
  • Patients with autoimmune conditions (rheumatoid arthritis, lupus, inflammatory bowel disease) — to monitor disease activity.
  • Post-surgery — to detect early infection.
  • hs-CRP: Adults at intermediate cardiovascular risk — to refine heart-disease risk assessment alongside lipid profile.
  • Patients with diabetes or metabolic syndrome — inflammation plays a role in insulin resistance.

How to Prepare#

  • No fasting required for standard CRP.
  • For hs-CRP (cardiovascular risk), some labs prefer a fasting sample for best accuracy.
  • Avoid strenuous exercise 24 hours before, as it can temporarily raise CRP.
  • Inform your doctor about recent infections, injuries, or surgeries, as these will elevate CRP independently of chronic conditions.

Understanding Your Results#

Standard CRP:

| CRP Level | Interpretation | |-----------|---------------| | Below 10 mg/L | Normal or mild inflammation | | 10–40 mg/L | Moderate inflammation (viral infection, mild bacterial infection) | | 40–200 mg/L | Active bacterial infection, autoimmune flare | | Above 200 mg/L | Severe infection, sepsis, major trauma |

hs-CRP (Cardiovascular Risk):

| hs-CRP Level | Heart-Disease Risk | |--------------|-------------------| | Below 1.0 mg/L | Low risk | | 1.0–3.0 mg/L | Average risk | | Above 3.0 mg/L | High risk |

An elevated hs-CRP combined with high LDL cholesterol significantly increases the risk of a cardiac event. Lifestyle modifications and statins can lower hs-CRP.

Related Tests#

  • CBC — WBC count helps identify infections causing raised CRP.
  • Lipid Profile — combined with hs-CRP for cardiovascular risk assessment.
  • Blood Sugar Fasting — metabolic syndrome link.
  • Urine Routine — to rule out UTI as a cause of raised CRP.

Booking & Home Collection#

Book a CRP test on PingMeDoc with home collection. No fasting typically needed. Results within 12–24 hours.

Frequently Asked Questions

5 questions answered by our medical team

1
What is the difference between CRP and hs-CRP?

Standard CRP measures higher levels of inflammation (useful for infections and autoimmune diseases). hs-CRP measures very low levels and is used specifically to assess cardiovascular risk.

2
Can stress raise CRP levels?

Yes, chronic psychological stress can mildly elevate CRP levels through systemic low-grade inflammation. Acute stress alone is less likely to cause a significant rise.

3
What should I do if my hs-CRP is high?

An elevated hs-CRP should be evaluated alongside your lipid profile, blood pressure, and other cardiovascular risk factors. Lifestyle changes (exercise, healthy diet, weight loss, quitting smoking) and statins can help lower hs-CRP.

4
How quickly does CRP rise and fall?

CRP can rise within 6–8 hours of an acute stimulus and peak at 48 hours. Once the cause resolves (e.g., infection treated with antibiotics), CRP falls rapidly with a half-life of about 19 hours.

5
Is CRP elevated in COVID-19?

Yes, CRP is commonly elevated in COVID-19 and has been used as a marker of disease severity. Very high CRP levels (> 100 mg/L) in COVID patients were associated with more severe outcomes.

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References & Sources

2 cited sources

  1. 1

    C-Reactive Protein Test

    Mayo Clinic2024View source
  2. 2

    hs-CRP and Cardiovascular Risk — AHA Scientific Statement

    American Heart Association2023

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