Background: Many girls with Turner syndrome (TS) are treated with growth hormone (GH) to increase adult height. In addition to promoting longitudinal bone growth, GH has effects on bone and body composition.

Objective: To determine how GH treatment affects bone mineral density (BMD) and body composition in girls with TS.

Method: In a cross-sectional study, we compared measures of body composition and BMD by DXA, and phalangeal cortical thickness by hand radiography in 28 girls with TS who had never received GH and 39 girls who were treated with GH for at least one year. All girls were participants in an NIH CRC protocol between 2001-2006.

Result: The two groups were similar in age (12.3 yr/ SD 2.9), bone age (11.5 yr/ SD 2.6), and weight (42.8 kg/ SD 16.6), but the GH-treated group was taller (134 cm vs. 137 cm, P = 0.001). The average duration of GH treatment was 4.2 /3.2 yr, range 1-14 yr. After adjustment for size and bone age there were no significant differences in BMD at L1-L4, 1/3 radius or cortical bone thickness measured at the 2^nd metacarpal. However, lean body mass percent was higher (P < 0.001) while body fat percent was lower (P < 0.001) in the GH-treated group. These effects were independent of estrogen exposure, and were still apparent in girls that had finished GH treatment a year or more previously.

Conclusions: While GH treatment has little effect on cortical or trabecular BMD in girls with TS, it is associated with increased lean body mass and reduced adiposity.