Biomarker

← Back to Glossary

Definition

A biomarker, or biological marker, is a measurable characteristic that reflects a biological process, disease state, or response to an intervention. Biomarkers can be molecules, genes, characteristics, or substances measured in blood, urine, tissues, or other body fluids that signal normal or abnormal processes.

Correct Scientific Usage

Scientists classify biomarkers by their purpose. For example, diagnostic biomarkers identify disease presence, prognostic biomarkers predict the likelihood of a future clinical event, and monitoring biomarkers track changes over time.

Researchers validate biomarkers through rigorous studies demonstrating specificity, sensitivity, and clinical utility before they become standard practice. Some biomarkers are used as surrogate endpoints when measuring long-term clinical outcomes directly is impractical.

Importantly, a biomarker’s role depends on context: a marker useful for diagnosis may not be appropriate for monitoring progression or predicting outcomes.

Common Misunderstandings

Biomarkers are often assumed to directly represent health or benefit. In reality, many biomarkers correlate with disease without causing it. A change in a biomarker does not automatically mean a patient will feel better, live longer, or avoid complications.

Why It Matters

Biomarkers can accelerate research and improve understanding of disease biology, but over-interpreting them can lead to false confidence. Knowing what a biomarker can—and cannot—tell us is essential for evaluating medical claims and clinical evidence.

References

← Back to Glossary