Bone in celiac disease

A short comment, not specific for celiac disease, on the use of the T- or Z-score to evaluate bone density in adults (in adults only, since in children and adolescents the Z-score must be used) may be useful at this point, to better understand the differences in bone density reported by different authors. By definition, the Z-score virtually coincides with the T-score in the 25–39 years age range. In older adults, the use of the T-score is universally accepted to define osteoporosis, osteopenia, or normality, according to the recommendations of a WHO Study Group [58]. There are strong scientific evidences of a clear relationship between the decrease of the T-score value and the increase of fragility fractures at any age. Thus, the T-score helps to evaluate the current risk of fractures, as well as the future risk. The Z-score, being the comparison with the mean value of healthy controls matched for both sex and age, is less useful in older adults, because some degree of bone loss is prevalent even among the apparently healthy subjects used as controls. However, the Z-score may help to understand how much the bone density of an individual affected by a disease is different from that of the healthy population of the same gender and age, and this may be the main reason why many studies on celiac patients with a wide age range used the Z-score.