The four types of biomarkers are molecular, histologic, radiographic, and physiologic characteristics. These are measurable indicators of a biological state or condition.
Here's a breakdown:
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Molecular Biomarkers: These involve the measurement of molecules such as DNA, RNA, proteins, metabolites, and lipids. Examples include:
- Specific protein levels in blood (e.g., cardiac troponin for heart attack).
- Genetic mutations indicating cancer risk or drug response.
- Levels of hormones (e.g., estrogen, testosterone).
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Histologic Biomarkers: These involve the microscopic examination of tissues. Examples include:
- Tumor grade and stage in cancer biopsies.
- Inflammation levels in tissue samples (e.g., liver biopsy in hepatitis).
- Presence of specific cellular markers using immunohistochemistry.
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Radiographic Biomarkers: These involve the use of imaging techniques to visualize and measure changes in the body. Examples include:
- Tumor size and response to treatment on MRI or CT scans.
- Bone density measurements using DEXA scans (for osteoporosis).
- Arterial plaque volume on angiography.
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Physiologic Biomarkers: These involve the measurement of bodily functions and processes. Examples include:
- Blood pressure.
- Heart rate.
- Respiratory rate.
- Forced expiratory volume (FEV1) in lung function testing.
It's important to note that a biomarker is not an assessment of how a person feels, functions, or survives; rather, it's an objective measurement that can correlate with those factors. Biomarkers are used for a variety of purposes, including:
- Diagnosis of disease
- Monitoring disease progression
- Predicting treatment response
- Identifying individuals at risk of developing a disease
