Lumbar and radial bone mineral density in children and adolescents with X-linked hypophosphatemia: evaluation with dual X-ray absorptiometry.
OBJECTIVE
To evaluate the bone mineral status of children being treated for X-linked hypophosphatemia, including potential differences between cortical bone in the radial diaphysis and combined cortical and trabecular bone in the lumbar spine.


METHODS
Forty-four bone mineral evaluations were performed in 11 children and adolescents with X-linked hypophosphatemia. Bone mineral density (BMD) of the lumbar spine and the radial diaphysis were measured by dual X-ray absorptiometry (DXA), second metacarpal cortical thickness was measured on hand radiographs, and these results were expressed as Z-scores (standard deviations from the mean).


RESULTS
For the 11 initial examinations, Z-scores (mean+/-SD) were: radial BMD, -2.73+/-1.15, lumbar BMD, +1.28+/-1.53; and cortical thickness, -2.21+/-0.95. Lumbar BMD Z-scores were significantly greater than those for radial BMD and cortical thickness. On follow-up examinations there was a mild increase in radial BMD and decrease in lumbar BMD. Although these changes were statistically significant, they were quite small and the discordance between radial and lumbar BMD was not corrected.


CONCLUSIONS
Children and adolescents who are being treated for X-linked hypophosphatemia manifest a bone mineral disorder characterized by decreased BMD in the appendicular skeleton and increased BMD in the lumbar spine. Although current therapy is successful in its anti-rachitic effects, it does not correct this bone mineral disorder and additional therapeutic trials should be considered.
Shore
R M
RM
Department of Radiology, The Children's Memorial Hospital, Chicago, IL 60614, USA.
Langman
C B
CB
Poznanski
A K
AK
D015502:Absorptiometry, Photon; D000293:Adolescent; D015519:Bone Density; D002648:Child; D002675:Child, Preschool; D018483:Diaphyses / Q000000981:diagnostic imaging / Q000378:metabolism; D005260:Female; D006801:Humans; D007015:Hypophosphatemia, Familial / Q000000981:diagnostic imaging / Q000235:genetics / Q000378:metabolism*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000378:metabolism*; D008297:Male; D011379:Prognosis; D011884:Radius / Q000000981:diagnostic imaging / Q000378:metabolism*