Which Blood Tests Reflect Aging and How to Read Them

By Longevity Lab · Published: July 21, 2026

Based on peer-reviewed research — full source list at the end of this article. This is educational information, not medical advice.

Four cheap, widely available measurements reflect aging and its risks better than anything else you can order: blood pressure, fasting glucose together with Glycated hemoglobin (HbA1c), a lipid panel, and waist circumference. Read them as a trend over time and as a set, because a single value in isolation tells you very little. Most of us see a doctor only once something hurts, but the diseases of aging — of the heart, the arteries, the metabolism — build quietly for years, and the first signal is usually a number on a lab report rather than a symptom. Below: which markers actually track aging and risk, where to start, how to read the results, and whether the fashionable biological age tests are worth paying for.

Why it pays to track your labs

The point of regular testing is early detection. Raised blood pressure, blood sugar or cholesterol give no warning for a long time, and all through that quiet stretch they are damaging blood vessels and organs. Caught early, almost any of these can be corrected with lifestyle changes or treatment, which is how you avoid a heart attack, a stroke or diabetes years later. In effect, the basic panel is the dashboard of your health: it shows risk long before anything breaks.

The basic markers to start with

These are cheap, widely available and well studied. The figures below are general reference points for adults, not a diagnosis; individual targets depend on your age and existing conditions.

*Approximate reference values; interpretation belongs with your doctor. These four markers cover most of the risk you can actually do something about, and they cost very little. Waist circumference deserves separate attention. Visceral fat — the fat stored inside the abdomen — is metabolically active and often matters more than total body weight. Because a raw waist measurement means different things on a tall and a short frame, many clinicians prefer the Waist-to-height ratio (WtHR), which scales the same tape measurement against your height.

Markers your doctor may add

Ordered by a clinician, these fill in the picture:

• High-sensitivity C-reactive protein (hs-CRP) — a marker of inflammation, used in cardiovascular risk assessment (see our piece on chronic inflammation).
• Vitamin D — particularly relevant at northern latitudes.
• Kidney and liver function, TSH — basic safety and metabolism.
• Complete blood count — simple, but an informative screen.

One caveat: a single test reflects a great deal, including a recent cold or a stressful week. So look at the trend and at the markers together, rather than at one number that happens to look bad. Vitamin D is a good example, since it swings with the season and a single winter reading says far less than the same figure repeated across a full year.

Biological age tests

Commercial “biological age” tests are a category of their own — most often epigenetic clocks, which estimate age from chemical tags on your DNA. They are interesting, and they suit tracking your own trend, but they come with limits: different tests return different numbers, they are expensive, and they rarely change a practical health decision. For most people the basic markers are more informative and far cheaper, and if you want an age-style number without paying for methylation sequencing, the PhenoAge Calculator — biological age from a blood test builds one out of the routine biomarkers a standard panel already contains. For what biological age even means, we have a separate primer on biological age.

How often to test

For healthy adults, checking the basic markers every one to two years is usually enough — more often if you have risk factors or an abnormal result. The decisive part is not the blood draw itself but going through the results with a doctor and following them over time. Tests without interpretation, and without anything changing afterwards, are useless. To prepare for that conversation, our companion guide on How to read your labs and manage your longevity shows how to decode each biomarker and follow it across repeat panels.

Frequently asked questions

Sources

Disclaimer. This article is for information only and does not replace medical advice. Talk to a qualified clinician before changing anything about your health.