DEXA Scan

What is a DEXA scan?

A DEXA scan (dual-energy X-ray absorptiometry) is a quick, very-low-dose X-ray exam that produces two results from a single pass over your body. The first is bone mineral density — the standard test for catching osteoporosis before a fracture happens. The second is body composition: an accurate breakdown of lean muscle mass, fat mass, and an estimate of visceral fat.

That second output is why DEXA has quietly become a staple of longevity medicine. Scales and smartwatch apps estimate body fat; DEXA measures it — precisely enough to track real changes in muscle and fat from one year to the next.

Understanding your T-score

Your bone density result is reported as a T-score — a comparison of your bone against the peak bone mass of a healthy young adult. It lands in one of three bands:

Those cut-offs are the World Health Organization's definition, and they are a classification rather than a verdict: the band decides what happens next — whether you re-scan in two years or have a treatment conversation — not whether you are ill. Bone loss is silent, and the first symptom is often the fracture itself. Caught at the osteopenia stage, it is largely manageable with diet, strength training, and, when needed, medication.

Two caveats the bands do not carry on their face. The WHO thresholds were originally derived for postmenopausal women, and applying them to other groups takes more care than a lookup table suggests — which is part of why the Z-score below exists. And the T-score is not the only route to a diagnosis: a fragility fracture — a break from a fall that should not have broken anything — can define osteoporosis on its own, even with a T-score above -2.5. The number is one input to a clinical judgement, not the judgement.

T-score vs Z-score — and why the comparison group matters

Your report may carry a second number, the Z-score. The difference is simply who you are being compared with. The T-score measures you against the peak bone mass of a healthy young adult. The Z-score measures you against people of your own age and sex.

It looks backwards to judge a 70-year-old against a 30-year-old — until you notice what the alternative does. Bone density declines with age in almost everyone, so an age-matched standard would quietly redefine the disease out of existence: at 75, having the bones of an average 75-year-old would score as "normal" even while your fracture risk is real and rising. Fractures do not care about percentiles. The young-adult comparison keeps the yardstick fixed to the structure that actually predicts a broken hip.

The Z-score earns its place elsewhere. In children, pre-menopausal women, and younger men, the young-adult standard is not the right frame, so the Z-score is used instead. It is also the number that flags a secondary cause: bone loss well below your own age group suggests something is actively driving it — a medication, a hormonal or digestive condition — rather than time alone. A markedly low Z-score is usually a prompt to look for that cause, not just to treat the density.

Reading your body composition numbers

The second half of the report is the half most people skim and then never think about again, which is a waste — it is where the actionable numbers live. Three of them matter.

Visceral fat — the number that outranks your weight

Visceral adipose tissue (VAT) is the fat packed in your abdomen around and between the organs. It is not the subcutaneous fat you can pinch under the skin, and the distinction is not cosmetic. Visceral fat is metabolically active tissue: it sits upstream of the liver, releases free fatty acids and inflammatory signalling molecules directly into the portal circulation, and is consistently associated with insulin resistance, unfavourable lipids, and cardiovascular risk. Subcutaneous fat is comparatively inert.

This is why two people at the same height and the same weight — the same BMI, on paper the same person — can have completely different metabolic risk. BMI is a ratio of mass to height. It cannot tell muscle from fat, and it cannot tell fat under the skin from fat wrapped around the liver. DEXA can, and it is the compartment, not the total, that carries most of the risk signal.

Be careful with the exact figure, though. DEXA does not photograph your visceral fat; it estimates it — as an area or a mass in the abdominal region — using a model applied to the density data, and manufacturers implement that model differently. A number from one scanner is not interchangeable with a number from another, and there is no single universal cut-off worth quoting. What is reliable is the direction of travel on the same machine: a VAT figure falling scan over scan is real information. A single absolute value, compared against a threshold you found online, mostly is not.

Muscle and appendicular lean mass

Your report breaks lean mass down by region, and the derived figure worth knowing is appendicular lean mass — the lean tissue in your arms and legs, the muscle that actually moves you. It is the standard basis for assessing sarcopenia, the age-related loss of muscle, and it is the number longevity-minded readers should probably care about most. Muscle is where glucose gets disposed of, it is what keeps you off the floor at 80, and unlike bone it responds to training at any age.

A single reading tells you where you stand. Its real value is as a baseline. Scales and bioimpedance devices swing with hydration and time of day; DEXA is precise enough that a year of lifting or a change in protein intake shows up as a measured difference rather than a hunch. That is the whole argument for repeating it.

Who should get one?

DEXA screening is recommended for post-menopausal women, for men from around age 70 — earlier with risk factors — and for anyone who wants a precise muscle-and-fat baseline:

• Post-menopausal women — the drop in estrogen accelerates bone loss, which is why women are the classic screening group
• Men 70 and older — or from 50 with risk factors such as long-term steroid use, a parent who fractured a hip, or low body weight
• Anyone tracking muscle and fat seriously — from athletes to people rebuilding strength, DEXA is the baseline that smart scales only approximate

What DEXA can't tell you

DEXA measures structure — bone mineral and tissue mass — not chemistry or organ detail. It cannot see cholesterol, blood sugar, or hormone levels; a comprehensive blood panel covers that half of a longevity baseline. It also says nothing about the organs themselves — that is the territory of a full-body MRI.

Two honest caveats. A low T-score tells you bone density is reduced, not why — an abnormal result starts a conversation with a physician rather than ending one. And body composition values vary slightly between machines, so trends are most meaningful when you re-scan on the same device.

What to expect on scan day

As standardly performed, a DEXA scan takes about ten minutes of lying still on an open table, usually fully clothed — no injections, no tunnel, no recovery time. The hospital confirms dress and any prep (such as pausing calcium supplements) when you book:

1. 1
   Check in — essentially no prep

   No fasting and no contrast. Wear clothing without metal (zippers, underwire); you may be asked to skip calcium supplements for 24 hours beforehand.
2. 2
   Lie still — about 10 minutes

   A scanner arm passes slowly above you while you lie flat on an open, padded table. Nothing touches you and nothing encloses you.
3. 3
   Done — straight to your next exam

   The radiation dose is trivial — roughly 1/100th of a chest X-ray — so the scan slots easily into a full screening morning.

What a DEXA scan costs

DEXA is cheap technology that turns expensive the moment it is billed through a health system. In the United States, published self-pay prices as of July 2026 have commonly sat in the low hundreds of dollars for a bone-density study, while body-composition DEXA at longevity and sports-medicine clinics is often sold per scan or bundled into a membership. Insurance typically covers bone density only against specific age and risk criteria; body composition is essentially never covered. Verify current pricing locally — it moves.

Because DEXA's real value comes from repeating it and watching the trend, the price per scan matters more than it looks. At New Dawn Health the scan is bookable on its own or added to a screening package; the live pricing further down this page comes from our booking system.

Results and follow-up

You receive both results in a written report: the T-score with its classification, and a body composition breakdown by region. Turnaround and who explains the numbers vary by hospital — your coordinator confirms both when you book. The explanation puts them in context — whether bone density warrants follow-up or treatment, and how your muscle-to-fat baseline compares. Because the dose is so low, DEXA is a repeatable measurement: many people re-scan every one to two years to confirm bone is holding steady and muscle is trending the right way.