General information

Serum Amyloid A (SAA) is an acute-phase protein, meaning it’s produced by the liver in response to inflammation, infection, or trauma. It plays an important role in the body's immune response.

• Inflammation marker: SAA levels rise very quickly—within 6 to 12 hours—after an inflammatory trigger. It can rise even faster and higher than CRP (C-reactive protein).

• Diagnostic use: SAA helps detect and monitor infections, autoimmune diseases, and certain cancers. When combined with other tests like CRP and blood counts, it can help distinguish between bacterial, viral, or mixed infections.

• Amyloidosis: In cases of chronic inflammation, excess SAA can deposit in tissues as amyloid fibers, leading to organ damage—a condition known as secondary amyloidosis.

• Feature	SAA (Serum Amyloid A)	CRP (C-Reactive Protein)	Procalcitonin (PCT)
  Onset of Increase	6–12 hours after inflammation	6–8 hours after inflammation	2–4 hours after bacterial infection
  Peak Concentration	24–48 hours	24–48 hours	6–24 hours
  Sensitivity	High for inflammation and autoimmune diseases	High for general inflammation	High for bacterial infections and sepsis
  Specificity	Low — rises in viral and non-infectious cases	Moderate — rises in many inflammatory states	High — rarely elevated in viral infections
  Best Use Case	Chronic inflammation, autoimmune disease, amyloidosis	General screening and monitoring of inflammation	Diagnosing bacterial infections and sepsis

   

  • SAA is the most sensitive to early and chronic inflammation, but not very specific — it can rise in viral infections, autoimmune flares, or even trauma.

  • CRP is a reliable, widely used marker for general inflammation but doesn’t distinguish well between causes.

  • PCT is your go-to when you need to know if an infection is bacterial — especially in cases of suspected sepsis or when deciding on antibiotic use.

  Sampling: venous blood