Bone health in children with inflammatory bowel disease: adjusting for bone age.
OBJECTIVE
Clinical results of bone mineral density for children with inflammatory bowel disease are commonly reported using reference data for chronological age. It is known that these children, particularly those with Crohn disease, experience delayed growth and maturation. Therefore, it is more appropriate to compare clinical results with bone age rather than chronological age.


METHODS
Areal bone mineral density (aBMD) was measured using dual energy x-ray absorptiometry, and bone age was assessed using the Tanner-Whitehouse 3 method from a standard hand/wrist radiograph. Results were available for 44 children ages 7.99 to 16.89 years. Areal bone mineral density measurements were converted to z scores using both chronological and bone ages for each subject.


RESULTS
Areal bone mineral density z scores calculated using bone age, as opposed to chronological age, were significantly improved for both the total body and lumbar spine regions of interest. When subjects were grouped according to diagnosis, bone age generated z scores remained significantly improved for those with Crohn disease but not for those diagnosed with ulcerative colitis. Grouping of children with Crohn disease into younger and older ages produced significantly higher z scores using bone age compared with chronological for the older age group, but not the younger age group.


CONCLUSIONS
Our findings, in accordance with those presented in the literature, suggest that aBMD results in children with Crohn disease should include the consideration of bone age, rather than merely chronological age. Bone size, although not as easily available, would also be an important consideration for interpreting results in paediatric populations.
University of Queensland, Children's Nutrition Research Centre, Discipline of Paediatrics and Child Health, Royal Children's Hospital, Herston, QLD 4029, Australia. rj.hill@uq.edu.au
Rebecca J
RJ
Hill
Denise S K
DS
Brookes
Peter J
PJ
Lewindon
Geoffrey D
GD
Withers
Looi C
LC
Ee
Frances L
FL
Connor
Geoffrey J
GJ
Cleghorn
Peter S W
PS
Davies
D015502:Absorptiometry, Photon; D000293:Adolescent; D000365:Age Determination by Skeleton / Q000379:methods*; D000367:Age Factors; D015519:Bone Density; D002648:Child; D003093:Colitis, Ulcerative / Q000000981:diagnostic imaging* / Q000503:physiopathology; D003424:Crohn Disease / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging* / Q000502:physiology; D008297:Male; D012016:Reference Values; D012737:Sex Factors