Assessing bone health in children: who to test and what does it mean?

The foundation of bone health is established during childhood and adolescence. Unfortunately, pediatric bone health may be threatened in a variety of genetic and acquired disorders. Low bone mineral density (BMD) and/or fragility fractures may result. This paper addresses the pediatric indications for bone densitometry testing in children at risk for poor bone health and the challenges of interpreting the results. Dual energy x-ray absorptiometry (DXA) is the most commonly used of the bone densitometry methods. Most DXA software programs report BMD in terms of a T-score, which compares the results to adult norms. Z-scores, based upon age- and gender-matched reference data, should be used instead to avoid the mislabeling of a child as "osteoporotic." Delayed growth and maturation also complicate the interpretation of DXA findings in chronically ill patients. Although children with low BMD values may have an increased risk of fracture, a pediatric "fracture threshold" has not been established. Further research is needed to refine the indications for bone density testing in children and to aid in the interpreting the results.