Normal DXA bone mineral density but frail cortical bone in Turner's syndrome.
BACKGROUND
Patients with Turner's syndrome have normal bone mineral density by dual energy X-ray absorptiometry (DXA), but a predisposition for fractures. Quantitative ultrasonography (QUS) measures cortical bone strength.


OBJECTIVE
To compare QUS with DXA in patients with Turner's syndrome.


METHODS
Twenty-seven Turner's syndrome patients, aged 21.1 +/- 6.3 years (mean +/- SD), were evaluated by DXA, measuring two-dimensional bone mineral density (BMD), and QUS, measuring speed of sound (SOS) of the radius and tibia. The results were compared to sex- and age-matched (Ctr A, n = 53) and height-matched (Ctr B, n = 34) control groups.


RESULTS
Fracture incidence per 1000 women years was 4.76 in Ctr A, 5 in Ctr B and 7.69 in Turner's patients. In Turner's syndrome patients, QUS results were significantly lower than in controls, whereas DXA Z-scores were not different from reference values. Correlation between tibia and radius SOS and height and age in controls (P < 0.0001) was not evident in Turner's syndrome. Oestrogen or growth hormone therapy had no effect on either QUS or DXA parameters.


CONCLUSIONS
Bone fragility in Turner's syndrome is reflected by low SOS but not by DXA BMD. Low QUS, which assesses the cortical bone only, supports a defect in cortical bone in Turner's syndrome. Lack of SOS correlation with age, height and hormonal therapy in Turner's syndrome suggests a primary bone defect, rather than enhanced resorption of endocrine origin.
Zuckerman-Levin
Nehama
N
Pediatric Endocrinology, Meyer Children's Hospital, Rambam Medical Center, Haifa, Israel. zuckerln@netvision.net.il
Yaniv
Irit
I
Schwartz
Tseela
T
Guttmann
Hadassah
H
Hochberg
Ze'ev
Z
D015502:Absorptiometry, Photon; D000293:Adolescent; D000328:Adult; D015519:Bone Density; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000503:physiopathology; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D011884:Radius / Q000000981:diagnostic imaging / Q000503:physiopathology; D011885:Radius Fractures / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology; D013977:Tibia / Q000000981:diagnostic imaging / Q000503:physiopathology; D013978:Tibial Fractures / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology; D014424:Turner Syndrome / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology; D014463:Ultrasonography