20 Biomarkers Worth Understanding: A Plain-Language Guide

What are biomarkers, anyway?

A biomarker is simply a measurable indicator of what's happening in your body. Blood tests measure biomarkers — molecules, cells, or enzymes — that reflect how well your systems are functioning. You don't need to be a scientist to understand them. Here are the 20 most useful ones, explained in plain language.

Metabolic biomarkers

These tell you how your body handles energy, blood sugar, and the building blocks of metabolism.

1. Fasting glucose

Blood sugar measured after not eating for 8–12 hours. The most basic indicator of how well your body manages sugar. Elevated levels may suggest insulin resistance.

2. Hemoglobin A1C (HbA1c)

Your average blood sugar over the past 2–3 months. Unlike a single glucose reading, it shows the trend, not just a snapshot. This is the marker doctors use to screen for prediabetes and diabetes.

3. Insulin (fasting)

The hormone that shuttles sugar from your blood into your cells. High fasting insulin can appear years before blood sugar rises — an early warning sign of metabolic strain.

4. Triglycerides

A type of fat your body stores and uses for energy. High triglycerides, especially with low HDL, can signal that your body is struggling to manage dietary fat and sugar efficiently.

Thyroid biomarkers

Your thyroid regulates metabolism, energy, temperature, and mood. Thyroid issues are common and often go undiagnosed.

5. TSH (thyroid-stimulating hormone)

The signal your brain sends to your thyroid. High TSH means your thyroid is underperforming (hypothyroid); low TSH may mean it's overactive (hyperthyroid).

6. Free T4

A circulating thyroid hormone that can be interpreted alongside TSH by a qualified clinician. ReachWell includes free T4 only in the female Advanced panel.

7. Cortisol

A hormone involved in the body's stress response and daily rhythm. Both ReachWell panels include a cortisol measurement.

Cardiovascular biomarkers

Heart and circulation markers trend slowly. Seeing them over time is more useful than any single reading.

8. LDL cholesterol

Often called 'bad' cholesterol. LDL particles can deposit in artery walls. The number matters, but particle size and count tell more — a standard panel gives you the basic level.

9. HDL cholesterol

Often called "good" cholesterol. HDL carries cholesterol away from arteries. Higher HDL is generally protective.

10. Total cholesterol

The sum of all cholesterol types. Less useful on its own, but provides context for the LDL/HDL breakdown.

11. hs-CRP

A highly sensitive measure of C-reactive protein, a marker of inflammation. Chronic inflammation is linked to cardiovascular risk. A single elevated reading isn't alarming — the trend over time matters.

Iron and oxygen biomarkers

Iron deficiency is one of the most common nutritional gaps, especially in menstruating women, pregnant women, and endurance athletes.

12. Ferritin

Your body's iron storage. Low ferritin can cause fatigue, brain fog, and exercise intolerance before standard anemia tests catch it. This is the most sensitive early marker of iron deficiency.

13. Hemoglobin

The protein in red blood cells that carries oxygen. Low hemoglobin indicates anemia, which can be caused by iron deficiency, B12 deficiency, or other factors.

14. Hematocrit

The percentage of your blood that's made up of red blood cells. Together with hemoglobin, it shows whether your blood is carrying oxygen efficiently.

Liver and kidney biomarkers

Your liver and kidneys filter, process, and detoxify. These markers show how well they're doing their job.

15. ALT (alanine aminotransferase)

A liver enzyme. Elevated ALT can indicate liver stress from fatty liver, alcohol, medications, or other causes. Mild elevations are common and often reversible.

16. AST (aspartate aminotransferase)

Another liver enzyme, also found in muscle. ALT is more liver-specific; AST elevations may come from muscle or exercise.

17. Creatinine

A waste product filtered by the kidneys. Used to calculate eGFR, a measure of kidney function.

18. eGFR

Estimated glomerular filtration rate — how well your kidneys are filtering blood. Below 60 may warrant follow-up with a healthcare provider.

Blood count biomarkers

Blood-count measurements can add context, but ReachWell does not include a full CBC. The Advanced panels include hematocrit.

19. Hematocrit

The percentage of blood made up of red blood cells. This measurement is included in both Advanced panel versions.

20. Vitamin D

A nutrient marker relevant to bone, muscle, and immune health. It is included in both Advanced versions and the female Essential panel.

Putting it together

No single biomarker tells the full story. The value is in the combination — seeing how your metabolic, thyroid, cardiovascular, iron, liver, kidney, and blood markers relate to each other, and how they change over time. That's what an annual panel gives you: a snapshot that becomes a trend. Take the free Health Clarity Assessment to find out which of these biomarkers are most relevant to your situation.

Common questions

What does a biomarker test show?

A biomarker test shows measurable indicators of how your body's systems are functioning — metabolism, thyroid, heart, iron, liver, kidneys, and blood. It gives you a snapshot that you can track over time.

Do I need to understand all 20 biomarkers?

No. The point of this guide is to make the terms approachable, not to make you a lab technician. ReachWell results are written in plain language so you can understand what each marker means for you.

How often should I check these biomarkers?

An annual check is enough for most adults to establish a meaningful trend. If a marker is borderline or changing, your results may suggest retesting sooner.

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20 Biomarkers Worth Understanding