Makindo Medical Notes

Related Subjects: |Ferritin |CEA |ESR |CRP |ALP |LDH |HbA1c |Alpha Fetoprotein |Anti-Hu ab |Biochemical Lab values

CRP (C-reactive protein) is an acute phase protein made in the liver, driven mainly by IL-6. It rises rapidly in acute inflammation but is poorly reliable in certain diseases: SLE, Scleroderma, Ulcerative Colitis, Leukaemia. 👉 Remember SLUL mnemonic. In these, ESR or disease-specific markers are more informative.

🧾 Overview

• CRP rises within 6–8 hours of a trigger, peaks by 48 hours, half-life ~19 hours.
• Falls quickly once inflammation resolves (unlike ESR).
• Acts as an opsonin, activates complement, and signals to immune cells.
• Useful for infection, post-operative complications, and cardiovascular risk prediction (hs-CRP).

🔬 Why CRP is Unhelpful in Some Diseases

• SLE 🦋: Type I interferon suppresses CRP production. ESR more reliable.
• Scleroderma: Fibrotic process with minimal acute-phase response.
• Ulcerative Colitis: CRP correlates poorly with flare severity (Crohn’s > UC for CRP).
• Leukaemia: Cytokine signalling is disrupted → blunted CRP response.

⚠️ Causes of Very High CRP

📊 CRP vs ESR

🔑 Clinical Pearls

• Normal CRP does not exclude flare in SLE, UC, scleroderma, leukaemia.
• CRP rises/falls rapidly → best for monitoring infection & treatment response.
• CRP >100 mg/L usually bacterial, <50 more often viral (but overlap exists).
• ESR + CRP together: ESR for chronic autoimmunity, CRP for acute infection.

📚 References

• NICE NG51: Sepsis
• BSR Biomarkers in Rheumatology