Biomarkers: what they tell you about health

A single number from a lab test can change treatment. Biomarkers are those numbers or molecules doctors use to spot disease, track progress, or pick the right medicine. Knowing the basics helps you ask better questions and avoid surprises when a doctor recommends a change in therapy.

Common biomarkers you should know

Here are simple examples you’ll see often: HbA1c for diabetes control, cholesterol panels (LDL/HDL) for heart risk, CRP for inflammation, troponin for heart damage, and PSA for prostate health. In cancer care, tests like EGFR or HER2 help decide targeted drugs. Some markers are measured in blood, others in urine or tissue. Each test has a clear purpose — screening, diagnosis, prognosis, or predicting how a drug will work.

Not every abnormal number means emergency. A slightly high CRP might reflect a recent cold. Troponin spikes usually mean heart injury, but timing and symptoms matter. That’s why context — symptoms, history, and imaging — always matters alongside a biomarker result.

How doctors use biomarkers to pick treatments

Biomarkers guide choices in three main ways. First, diagnostic markers confirm a condition (like using HbA1c to diagnose diabetes). Second, prognostic markers estimate how a disease might behave (some cancer markers suggest more aggressive disease). Third, predictive markers show whether a drug is likely to help (for example, a tumor test that predicts response to a targeted therapy).

If your doctor suggests a new drug because of a biomarker, ask: “Which marker changed? What does that mean for risks and benefits? Are there alternative tests or repeat checks?” These questions help you understand whether a medication change is urgent or optional.

Practical tips before testing: follow prep instructions (fasting for certain lipids), bring a current medication list, and note recent illnesses that could affect results. If a result seems off, repeat testing or checking with a specialist is often smarter than rushing into a new medication.

Remember limits: lab assays differ between labs, and reference ranges vary with age and sex. Results must be read in context. False positives and false negatives happen, especially with screening tests.

For people managing meds, biomarkers matter because they show response and side effects. Regular liver or kidney markers, for example, are standard when you start many drugs. If a marker moves in the wrong direction, your doctor may lower the dose, switch drugs, or add monitoring — not always stop treatment entirely.

If you want to use biomarkers to improve care, keep records of your test dates and values, share them with new providers, and ask for plain-language explanations. Good labs and a straightforward discussion with your clinician turn numbers into useful decisions — not just anxiety.

Need more on specific markers or how they affect medications? Check our guides and drug pages for clear, practical info tailored to common tests and treatments.