Usefulness of phalangeal quantitative ultrasound in identifying reduced bone mineral status and increased fracture risk in adolescents with Turner syndrome

OBJECTIVE. Bone health is a major concern in patients with Turner syndrome (TS). There are few studies assessing bone mineral status in TS adolescents and none have reported a clear relationship with the risk of fracture. We assessed bone mineral status at three different skeletal sites by two different densitometric techniques in a group of TS adolescents. DESIGN. In 24 TS adolescents (17.1 +/- 3.1 years) we evaluated lumbar and femoral volumetric bone mineral density (vBMD) with dual energy X-ray absorptiometry (DXA), amplitude-dependent speed of sound (AD-SoS) and bone transmission time (BTT) with phalangeal quantitative ultrasound (QUS). RESULTS. Mean lumbar vBMD Z-score was normal, while mean femoral vBMD, AD-SoS and BTT Z-score were reduced. 8/24 (33.3%) and 13/24 (54.2%) girls had AD-SoS and BTT <=-2 Z-score, respectively, while lumbar vBMD and femoral vBMD were <=-2 Z-score only in 2/24 (8.4%) and 1/24 (4.2%) patients. Overall, we documented 15 fractures (three pathological) in 8 girls. Patients who reported at least one fracture had lower AD-SoS and BTT Z-score values than fracture-free girls. The presence of a value of BTT <=-2.0 Z-score was associated with a significant OR of positive history of fracture of 11.67 (chi(2)=5.906, p = 0.015, C.I. 95% 1.14-119.54). Lumbar and femoral vBMD were not related to fracture risk. CONCLUSIONS. TS adolescents may have impaired bone mineral status in skeletal sites with predominant cortical bone. Phalangeal QUS represents a useful method to identify subjects with increased fracture risk.