Biomarker

A biomarker (short for biological marker) is a measurable indicator of a biological state or condition. Biomarkers can be molecules found in your blood, urine, or other body fluids; physical characteristics like blood pressure or heart rate; or imaging findings like the size of a tumor. They provide objective data points that help doctors diagnose diseases, monitor how well a treatment is working, and predict health outcomes.

You encounter biomarkers every time you have routine blood work. Your fasting glucose level is a biomarker for diabetes risk. Your LDL cholesterol level is a biomarker for cardiovascular risk. Your hemoglobin A1c (HbA1c) is a biomarker that reflects your average blood sugar over the past 2-3 months. Tumor markers like PSA (prostate-specific antigen) and CA-125 are biomarkers used in cancer screening and monitoring.

Advances in genomics, proteomics, and precision medicine are rapidly expanding the universe of clinically useful biomarkers. Genetic biomarkers can now predict your risk for certain diseases, identify which medications will work best for you (pharmacogenomics), and guide cancer treatment decisions based on the molecular profile of a tumor rather than just its location in the body.

Biomarkers are the foundation of evidence-based medicine and preventive health screening. Your annual physical likely includes measurement of multiple biomarkers — blood pressure, fasting glucose, lipid panel, complete blood count — that collectively paint a picture of your overall health and disease risk.

Understanding your personal biomarker trends over time is more valuable than any single measurement. A fasting glucose of 105 mg/dL on one test is less informative than knowing your glucose has risen steadily from 90 to 105 over the past five years, which might indicate emerging insulin resistance even though each individual reading was within normal range.