Bone densitometry, BMD or DEXA: the order always means the same exam, and it has to be booked away from other studies

This is one of the most acronym-dense exams there is. DMO in the medical record, DEXA or DXA on the report, densitometry in conversation, and the full anatomy in the catalogue. Four doors to the same machine.

What does it measure and where?

The RSNA reference on bone densitometry describes an exam that uses a very small dose of ionising radiation to produce images of the inside of the body and measure bone loss. The report comes back with a score that the treating doctor interprets, and that reading belongs to the next visit.

The FONASA fee schedule carries a single code for dual-photon bone densitometry of spine and hip, unilateral or bilateral, or whole body. If your order says spine densitometry and someone else's says hip densitometry, both land on the same service.

What has to be settled before the appointment?

• The exams you had before. RSNA asks patients to report a recent barium study or contrast injection, and mentions a wait of 10 to 14 days before the densitometry. If you are also holding a CT scan order with contrast, the sequence you book them in changes the date of one of the two.
• Supplements. The same reference mentions not taking calcium supplements in the hours before the exam. The exact window is set by your centre's protocol, so ask when you book.
• Clothing. RSNA recommends loose, comfortable clothes without zips, belts or metal buttons, and removing jewellery and metal objects.
• Pregnancy. Women should always tell the doctor or technologist if they are pregnant.

How long does it take?

RSNA puts the exam at 10 to 30 minutes, depending on the equipment. You lie fully dressed on a table while the arm of the machine passes over the areas requested. No injections, no tunnel, no long fast.

What does the centre ask for besides the order?

Previous densitometries if they exist, because much of the value of this exam lies in the comparison with the last one. And the referral paperwork when a specialist issued the order, because several insurance agreements require it before releasing the appointment slot.

Why does it go unbooked?

Because nothing hurts and no symptom pushes. Densitometry is ordered at a routine check-up, often alongside orders that look more urgent, and it ends up at the bottom of the envelope. Nothing reminds the patient it exists until the next visit, which may be a year away.

The other reason is availability. Not every centre has a densitometer, so the appointment usually lands at another site, and that trip is enough for the order to be postponed indefinitely.

Today your centre can keep track of that order and write to you before it expires. Find out whether they work with Surface.