In short
DEXA is most often used as a bone density test, and some clinics also offer it to estimate body composition. MedlinePlus says the scan is painless and the radiation dose is low. A 2025 review of children and adolescents describes DXA as the reference standard for body composition. Two clinics may advertise a DEXA scan but offer different things, so compare what is included.
On this page
DEXA (dual-energy x-ray absorptiometry) is most often used as a bone density test. MedlinePlus describes it as the most common and accurate bone density test.1 It measures the calcium and other minerals in a section of bone, and it is used to look for bone loss and to estimate fracture risk.
How the scan works
In a central DEXA scan you lie on a table while the scanner passes over your lower spine and hip. MedlinePlus says you usually do not need to undress, the scan is painless, and you need to stay still.1 The radiation dose is low: MedlinePlus notes that a chest x-ray exposes you to more.1
MedlinePlus lists two preparation points: do not take calcium supplements for 24 hours before the test, and remove metal items such as jewellery and belt buckles.1 Clinics may give their own instructions, so follow those.
DEXA for body composition
Some clinics offer DEXA to estimate body composition, meaning fat, lean tissue and bone. A clinic may offer a bone density scan, a body composition scan, or both, so check which one your booking includes.
DEXA compared with bioelectrical impedance
Bioelectrical impedance (BIA) devices, such as many body-composition scales, estimate body composition from an electrical signal. A 2025 systematic review of children and adolescents describes DXA as the reference standard for body composition.2 It found that BIA tends to underestimate body fat, especially at higher body fat, and that accuracy depends on the device.2 The review treats BIA as useful for tracking groups and changes over time, and less reliable for an individual reading.2
That review covers children and adolescents2, so results for adults may differ.
What this means for comparing prices
Two clinics may both advertise a "DEXA scan" but offer different things, such as a bone density scan or a full body-composition report. When you compare prices, compare what is included.
Sources
- MedlinePlus: Bone density scan
- Systematic review: bioelectrical impedance versus DXA in children and adolescents (2025)
Last reviewed 2026-10-16. This page is general information, not medical advice. Talk with a health professional about your own situation.