Introduction to Biomarkers
- Biomarkers are measurable indicators of biological states.
- They are used for disease diagnosis, prognosis, and monitoring.
- Biomarkers can be proteins, genes, enzymes, or structural changes.
- They can be classified as markers of exposure or markers of disease.
Characteristics of an Ideal Biomarker
| Characteristic | Description |
|---|---|
| High sensitivity with organ specificity | Accurate detection of organ-related changes. |
| Immediate release with tissue injury | Rapid response to tissue damage. |
| Release proportional to insult | The extent of release correlates with the injury. |
| Long half-life for predictiveness | Sustained presence for predictive purposes. |
| Rapid decrease in concentration for monitoring | Quick clearance for monitoring. |
| Rapid, simple, accurate, and inexpensive measurement | Easy and cost-effective assessment. |
| Noninvasive and accessible | Easily obtainable without invasive procedures. |
Biomarkers of the Cardiovascular System
| Biomarker | Description | Clinical Applications |
|---|---|---|
| C-reactive Protein (CRP) | Marker of inflammation, linked to heart disease | Risk assessment for coronary artery disease, rheumatoid arthritis, and lupus. |
| Cardiac Troponins | Indicators of heart muscle damage | Diagnosis of myocardial infarction and risk assessment in patients with end-stage renal disease. |
| B-type Natriuretic Peptide (BNP) | Reflects heart failure | Diagnosis and prognosis in congestive heart failure. |
| Soluble Urokinase Plasminogen Activation Receptor (suPAR) | Inflammation marker | Risk prediction for cardiovascular disease. |
Biomarkers of Kidney Injury
| Biomarker | Description | Clinical Applications |
|---|---|---|
| Neutrophil gelatinase-associated lipocalin (NGAL) | Reflects kidney injury | Early diagnosis and risk prediction of acute kidney injury. |
| N-Acetyl-b-D-Glucosaminidase (NAG) | Enzyme found in kidney tubules | Prediction of renal replacement therapy in AKI patients. |
| Urinary cystatin C and Plasma cystatin C | Reflect kidney function | Diagnosis and prediction of AKI and assessment of glomerular filtration rate. |
| Kidney injury molecule-1 (KIM-1) | Marker of kidney injury | Prediction of AKI and adverse outcomes. |
| Interleukin 18 (IL-18) | Reflects inflammation | Predicts death or AKI. |
Biomarkers of Gut Failure
| Biomarker | Description | Clinical Applications |
|---|---|---|
| Citrulline | Marker of enterocyte mass | Indicator of enterocyte damage and bacterial translocation. |
| Fatty Acid-binding Protein (I-FABP) | Reflects intestinal epithelium damage | Early detection of intestinal injury. |
| Procalcitonin (PCT) | Pro-inflammatory marker | Differentiates bacterial from viral infections and guides antibiotic use. |
| MicroRNA (miRNA) | RNA molecules reflecting cellular changes | Potential for diagnosing various disorders and sepsis. |
Biomarkers of Brain Damage and POCD
| Biomarker | Description | Clinical Applications |
|---|---|---|
| S100B protein | Found in astroglial Schwann cells | Used in detecting brain damage in surgery and trauma. |
| Metalloproteinases (MMP) | Reflects blood-brain barrier dysfunction | Associated with postoperative cognitive dysfunction (POCD). |
| Α-II Spectrin Breakdown Product (SBDP) 145,150,120 | Reflects neuronal injury | Potential marker for traumatic brain injury. |
Conclusion
- Biomarkers play a crucial role in diagnosing and monitoring various medical conditions.
- While promising, their accuracy and clinical relevance may vary.
- More research is needed to validate the use of newer biomarkers in clinical practice.
