Chapter 2 Innate and Adaptive Immunity: From Cell Defense to Tissue Repair
Section 11: Diagnostic Tests – Blood Biomarkers
Zoë Soon
Changes in blood composition provide valuable diagnostic clues about the cause and extent of cellular damage:
| Inflammatory plasma proteins | Damaged cells stimulate increased production of prothrombin, fibrinogen, C-reactive proteins (CRP), and plasminogen |
| Antibodies and complement proteins | Rise during infection. |
| RBC count & Hemoglobin | Oxygen-carrying capacity
Erythrocytopenia (reduced RBCs) → blood loss, sickle cell anemia, deficiency in iron, vitamin B12, folate, amino acids. |
| WBC differential | Neutrophilia (elevated neutrophils) → bacterial infection;
Eosinophilia → helminth infection; Lymphocytosis (elevated lymphocytes) → viral infection. Thrombocytopenia → bone marrow depression |
| Liver enzymes | Damaged hepatocytes release liver enzymes (e.g., ALT, GGT and AST) into the bloodstream. |
| Cardiac proteins | Damaged cardiomyocytes (in myocardial infarction) release cardiac troponin, actin, myosin, and creatine kinase into the bloodstream. |
| Hormones | Measure of endocrine production |
| Nutrients | Monitor for any dietary deficiencies |
| Wastes | Reflects organ function involved in waste removal |
