CRP (C-Reactive Protein) Blood Test

What is Included In the CRP (C-Reactive Protein) Test?

• A Blood test
• 10-minute appointment
• No GP referral required
• Results sent electronically within 7 Working Days.

Please note: We only scan patients over the age of 18 years. For multiple pregnancies, there is an additional charge of £25

What is a CRP Blood Test?

A C-reactive protein (CRP) blood test measures the amount of CRP, which is a protein that’s produced by the liver when inflammation occurs anywhere in the body. Inflammation is part of the immune system’s defence mechanism. It can be triggered by infection, injury, autoimmune reaction, and chronic disease. CRP levels can rise dramatically within hours of the onset of inflammation and fall quickly once the main issue improves. That’s why it’s an effective short-term marker of active disease.

CRP circulates in the bloodstream and is measured in milligrams per litre (mg/L). A very low level is normal. Mild elevations may indicate low-grade inflammation, whereas significant rises may point to bacterial infection, systemic inflammation, and tissue damage.

Why might someone have a CRP test?

Clinicians order CRP tests when the patient’s symptoms suggest infection or inflammation (e.g., fever, pain, swelling, joint stiffness, unexplained tiredness). It is commonly used in conditions such as rheumatoid arthritis, inflammatory bowel disease, and lupus to monitor disease progress. It can also help determine whether antibiotics are necessary or whether treatment is working.

A specific version (the high-sensitivity CRP (hs-CRP) test) may be used to estimate cardiovascular risk. Persistently elevated CRP can signal low-grade vascular inflammation associated with heart disease.

Limitations of the CRP Test

CRP is a non-specific marker and does not identify where inflammation originates or what causes it. Levels may rise due to smoking, obesity, strenuous exercise, and minor infections. A normal result cannot completely exclude illness, especially in early or localised conditions. Therefore, interpretation must always consider the patient’s full clinical picture.

Preparation for the CRP Test

No fasting is needed. Patients may eat, drink, and take their usual medications unless advised otherwise. It’s recommended to stay hydrated before the appointment to make the blood draw easier and more comfortable.

When will my results become available?

Your results are usually available within 7 working days. Because CRP responds rapidly to change, repeat tests may be used to track progress. Doctors interpret results in context with symptoms, medical history, and other investigations. However, a one-time CRP test may be useful to see whether you have low-grade inflammation of unknown cause.