Bone Assessment in Children: Clinical Relevance and Interpretation

The assessment of bone in children is more difficult than in adults mainly due to the effect of growth and/or puberty. Despite this, there is an increasing body of evidence showing that measurement of different components of bone is of clinical relevance. Fracture incidence peaks during the early teenage years, and dual energy X-ray absorptiometry (DXA) has been shown to predict fractures in children, especially those of the upper limb, in four prospective studies. Case control and cross-sectional studies have also shown similar associations for peripheral quantitative computed tomography (pQCT), heel ultrasound, metacarpal index, and skeletal age deviation. In some cases, these latter results are additive to DXA suggesting a multifaceted approach to bone assessment in children will lead to greater information. Size or age adjusted Z scores are mandatory for the interpretation of DXA in children. However, other modalities such as heel ultrasound are less affected by growth. Lastly, children have very high bone turnover in comparison to adults but markers of bone turnover also have clinical utility for linear growth, assessment of the impact of vitamin D deficiency and assessment of short term influences on bone such as diet.