Endocrine Abstracts

Aim: To evaluate bone mineral density (BMD) in children with different karyotype variants of Turner syndrome (TS) depending on the stage and the onset of puberty (spontaneous or induced).

Methods: The total studied group consisted of 75 children with TS from 8 to 17 years (mean age 14.2 ± 2.61), who were regularly followed-up in the University hospital (Minsk) and age matched 25 healthy controls. TS was diagnosed according to the results of karyotyping at the age of 8.2 ± 5.16 years. 22 patients were in prepuberty (mean age 11.4 ± 2.1 years). 53 girls had II-V stage of puberty according to Tanner (mean age 15.26 ± 1.95 years). Spontaneous onset of puberty was observed in 14 girls aged 12.07 ± 1.66 years. 39 patients underwent puberty initiation (the age for starting estrogen replacement therapy was 13.27 ± 1.26 years). Depending on the karyotype, 3 groups of patients were identified: group 1 - with karyotype 45,X (n = 42), group 2 - with mosaic karyotype 45,X/46,XX (n = 9), group 3 - with structural anomalies of X chromosome (n = 24). Body composition with evaluating of mineral component was made by DEXA with the calculation of lumbar spine (L_1-4) BMD (g/cm²) and Z-test.

Results: 54.5% of prepubertal patients with TS revealed low BMD of lumbar spine L_1-4 vs 64.1% in pubertal girls. A significant increase of BMD was revealed in patients of puberty age in comparison with the group of prepubertal children (0.95 [0.85;1.02] g/cm² vs 0.76 [0.69;1.82] g/cm², P = 0.0001). A statistically significant increase in the Z-test in this groups was not established (–1.25 [–1.95; –0.78] vs –1.1 [–1.7; –0.4], P = 0.2). There were no differences in BMD depending on karyotype both at the prepuberty and puberty age. The BMD of the lumbar spine (L_1-4) was significantly lower both in patients with spontaneous puberty and in the group of girls with estrogen replacement therapy compared to the control group. In girls with TS and spontaneous puberty a low BMD was detected in 57.2% of cases (Z = −1.9 ± 0.87), whereas in the group with stimulated puberty - in 68.4% of patients (Z = −1.8 ± 0.62). A direct correlation of spine BMD and estrogen therapy duration (rs = 0.6, P = 0.0001) was found in girls with TS.

Conclusions: A significant increase in BMD without an improvement in the Z-test was found in pubertal patients with ST in contrast to prepubertal children. Decreased of BMD are more often diagnosed in patients with stimulated puberty, due to the later initiation of estrogen therapy. Long-term estrogen replacement improves BMD.