Dual-energy X-ray Absorptiometry - Current Clinical Practice in Paediatrics

Current Clinical Practice in Paediatrics

DXA is, by far, the most widely used technique for bone measurements, since it is considered to be cheap, accessible, easy to use, and able to provide an accurate estimation of bone mineral density in adults.

The official position of the International Society for Clinical Densitometry (ISCD) is that a patient may be tested for BMD if he suffers from a condition that could precipitate bone loss, is going to be prescribed pharmaceuticals known to cause bone loss, or is being treated and needs to be monitored. The ISCD states that there is no clearly understood correlation between BMD and the risk of a child's suffering a fracture; the diagnosis of osteoporosis in children cannot be made using the basis of a densitometry criteria. T-scores are prohibited with children and should not even appear on DXA reports. Thus, the WHO classification of osteoporosis and osteopenia in adults cannot be applied to children, but Z-scores can be used to assist diagnosis.

Some clinics may routinely carry out DXA scans on paediatric patients with conditions such as nutritional rickets, lupus, and Turner Syndrome. DXA has been demonstrated to measure skeletal maturity and body fat composition and has been used to evaluate the effects of pharmaceutical therapy. It may also aid paediatricians in diagnosing and monitoring treatment of disorders of bone mass acquisition in childhood.

However, it seems that DXA is still in its early days in paediatrics, and there are widely acknowledged limitations and disadvantages with DXA. A view exists that DXA scans for diagnostic purposes should not even be performed outside specialist centers, and, if a scan is done outside one of these centers, it should not be interpreted without consultation with an expert in the field. Furthermore, most of the pharmaceuticals given to adults with low bone mass can be given to children only in strictly monitored clinical trials.

Whole-body calcium measured by DXA has been validated in adults using in-vivo neutron activation of total body calcium but this is not suitable for paediatric subjects and studies have been carried out on paediatric-sized animals.