- Pathophysiology
- Proteins whose concentrations change by >25% during inflammation, triggered by infection, trauma, or autoimmune conditions.
- Production is stimulated by pro-inflammatory cytokines (IL-6, IL-1, TNF-α) acting on the liver.
- Positive Reactants (Concentration ↑)
- C-Reactive Protein (CRP): Opsonin that activates complement. A rapid and sensitive marker of inflammation.
- Fibrinogen: Coagulation factor. Its elevation is the primary cause of an increased Erythrocyte Sedimentation Rate (ESR).
- Ferritin: An iron-binding protein that sequesters iron, making it unavailable to microbes. Contributes to Anemia of Chronic Disease.
- Hepcidin: Degrades ferroportin to trap iron in macrophages and reduce gut absorption. A key driver of Anemia of Chronic Disease.
- Serum Amyloid A (SAA): Chronic elevation can lead to secondary amyloidosis (AA amyloidosis).
- Procalcitonin: Levels rise significantly in bacterial infections and are used to differentiate bacterial from viral causes. t
- Negative Reactants (Concentration ↓)
- Liver decreases their synthesis to conserve amino acids for positive reactants.
- Albumin: Most abundant plasma protein. Low levels can also indicate malnutrition or nephrotic syndrome.
- Transferrin: Iron transport protein. Levels decrease to sequester iron.
Mnemonic
- ↑ESR: 胆固醇↑，球蛋白↑，纤维蛋白原↑——荡秋千
- ↓ESR: 白蛋白↑，卵磷脂↑——洁白的鹅卵石