DEXA Scan Results Interpretation: How to Read Your Report, Line by Line

A bone density report can feel like being handed someone else's spreadsheet: unfamiliar region names, numbers to three decimal places, more than one score per row. In fact it is a short, predictable document - and once you know what each line is for, most of the worry goes out of it.

What is actually printed on a DEXA scan report?

Underneath the letterhead, a DEXA report is a table: one row per skeletal site, and for each site a bone mineral density figure in g/cm² plus a T-score and, where appropriate, a Z-score. The International Society for Clinical Densitometry sets a minimum for what a baseline report should contain, including the BMD in g/cm² for each site, the skeletal sites and regions of interest scanned, the T-score and/or Z-score where appropriate, and recommendations for the necessity and timing of your next scan. It also says the report should explain why any acquired exam was not reported, or flag where a technically acceptable DXA exam has aspects that might confound the results. ISCD Official Adult Positions

One thing confuses people immediately: your report may say DXA where you expected DEXA. The NHS describes the test as dual energy X-ray absorptiometry, "shortened to DEXA", NHS, 2022 while the ISCD's own nomenclature position is "DXA - not DEXA". ISCD Official Adult Positions Same test, two spellings. For what the test can and cannot see, see our guide to what a DEXA scan shows.

Which parts of the body does the report cover?

Your spine and your hip, in almost every case. The Royal Osteoporosis Society describes a scanning arm passing over your body to take images of your spine and hips, "two of the most common places where bones break", and notes that sometimes your wrist is scanned too. Royal Osteoporosis Society The ISCD position is blunter: measure BMD at both the PA spine and hip in all patients. ("PA" in its glossary simply stands for posterior-anterior.) ISCD Official Adult Positions

If your report has a forearm row, there is usually a reason for it. The ISCD lists forearm measurement for three circumstances: the hip and/or spine cannot be measured or interpreted, hyperparathyroidism, and patients over the weight limit for the DXA table. ISCD Official Adult Positions

What does "L1-L4" mean on the spine row?

L1 to L4 are the top four vertebrae of your lower back, and the spine result is normally the four of them measured together rather than individually. The ISCD position is to use PA L1-L4 for spine BMD measurement, using all evaluable vertebrae and excluding only those affected by local structural change or artifact - with three vertebrae used if four cannot be, and two if three cannot be. ISCD Official Adult Positions

That exclusion rule is why your report may quote "L1-L3" or "L2-L4". It is not sloppiness. A vertebra can be excluded if it is clearly abnormal and non-assessable at the resolution of the system, or if there is more than a 1.0 T-score difference between it and the vertebrae next to it; the remaining ones then derive the T-score. If only one evaluable vertebra is left, diagnosis should be based on a different valid skeletal site altogether. ISCD Official Adult Positions Structural change in the lower spine is one reason a level gets dropped - see whether a DEXA scan shows arthritis.

What do "femoral neck", "total hip", "trochanter" and "Ward's area" mean?

They are different regions of interest within the same hip - and only two are used for diagnosis. The femoral neck is part of the top of your thigh bone, and one of the places scanned during a bone density scan. Royal Osteoporosis Society The ISCD's instruction is to use the femoral neck or the total hip, whichever is lowest, and either hip may be measured; other hip regions of interest, including Ward's area and the greater trochanter, should not be used for diagnosis. ISCD Official Adult Positions

Row on your report	What it is	Used for diagnosis?
Lumbar spine (L1-L4)	The four lower-back vertebrae, measured together	Yes
Femoral neck	Part of the top of the thigh bone	Yes - and the WHO international reference standard site
Total hip	The total proximal femur - the upper end of the thigh bone	Yes
Greater trochanter	A bony prominence on the upper thigh bone	No
Ward's area	A small region of interest within the hip	No
33% (one-third) radius	A site on the non-dominant forearm	Only in certain circumstances

What does the BMD number in g/cm² actually mean?

It is the raw measurement - grams of bone mineral per square centimetre of the area scanned - and every score on the page is derived from it. The unit tells you this is density per unit area rather than per unit volume.

Precision is a useful clue that you are reading the right column: the ISCD's preferred format gives BMD to three decimal places (its example is 0.927 g/cm²) and T-scores and Z-scores to one (examples, -2.3 and 1.7). ISCD Official Adult Positions The scores come from comparing your density against reference data - the NHS describes your measurements being compared with the bone density of a young healthy adult, or of an adult of your own age, gender and ethnicity. NHS, 2022 For what the bands mean, see our guide to DEXA results and the T-score.

Why do my spine and hip scores disagree?

Because they are different bones, measured separately, and not even scored against the same reference database. This is the most surprising line in the ISCD positions: manufacturers should continue to use NHANES III data as the reference standard for femoral neck and total hip T-scores, but their own databases for the lumbar spine. ISCD Official Adult Positions Two sites, two yardsticks - so a modest gap is expected rather than alarming.

It is also common. In a cross-sectional study of 1,429 patients aged 60 and over at a single centre, discordance between femoral and lumbar results was found in 41.6%: minor discordance - where the two sites give different diagnoses, such as osteoporosis at one and osteopenia at the other - in 39.4%, and major discordance, osteoporosis at one site with normal density at the other, in just 2.2%. Annals of Saudi Medicine, 2024 That was an older Saudi cohort rather than a UK average, but the pattern is clear: mild disagreement is common, while a dramatic split is rare. Where the two straddle a threshold, the lowest valid site carries the diagnosis - and our guide to T-scores versus Z-scores explains which score applies to you.

Which number on the report is my diagnosis?

For postmenopausal women and men aged 50 and over, it is the T-score at the lumbar spine, total hip or femoral neck, and osteoporosis may be diagnosed if that score is -2.5 or less. The WHO international reference standard for diagnosis is a T-score of -2.5 or less at the femoral neck, calculated from the female, white, age 20-29 NHANES III database. ISCD Official Adult Positions

If you are younger, the headline number changes. Before the menopause, and in men younger than 50, the ISCD prefers Z-scores to T-scores; a Z-score of -2.0 or lower is defined as "below the expected range for age". Osteoporosis cannot be diagnosed in men under 50 on the basis of bone density alone. ISCD Official Adult Positions

Either way, the report is not the whole answer. The NHS notes that bone density results are usually used alongside a fracture risk assessment, NHS, 2022 and the Royal Osteoporosis Society is direct that scan results "do not give a complete picture of your bone strength". Royal Osteoporosis Society Our guide to interpreting a FRAX score covers the other half.

What should a follow-up report show that your first one does not?

A comparison. The ISCD sets different requirements for a follow-up report: it should state which previous or baseline study and region of interest is being used, state the least significant change at that facility and the statistical significance of the comparison, and report the significant change (if any) between studies in both g/cm² and percentage. ISCD Official Adult Positions

That least significant change is facility-specific, which is the technical reason behind advice you may already have been given: the Royal Osteoporosis Society says repeat scans are normally every two to five years because bone density changes very slowly, that if you have scans too close together you will not see any change, and that they are best done at the same hospital and, if possible, the same machine. Royal Osteoporosis Society Our guide to how often you should have a bone density scan covers the timing.

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This article is part of our screening technology series.