In two groups of girls with Turner’s syndrome before treatment with growth hormone (GH), during treatment and after its termination bone density (BMD) was examined by two-photon densitometry (DEXA, Lunar DPX-L, Lunar Corp.) in the area of L2-L4. In 20 prepubertal girls GH treatment was started at the age of 10.0 ± 1.4 years (mean ± SEM), bone age 8.4 ± 1.3 years. Before GH treatment the BMD z-score related to chronological age (BMD-CA) was significantly reduced (-1.75 ± 0.28), while the z-score related to bone age (BMD-BA) (-0.42 ± 0.19) and to height age (BMD-HA) (0.18 ± 0.13) was within the normal range. After two years of GH treatment an increase of the z-score of BMD-CA occurred to -0.59 ± 0.18 (p<<0.05) and the z-score of BMD-BA to 0.29 ± 0.21 (p<<0.05). The z-score of BMD-HA did not change significantly. Before treatment and during the 3-year period of GH treatment the z-score of BMD-CA correlated with the patient’s height (p<<0.05). Girls who were older at the onset of GH treatment than 10 years had the BMD lower (-2.31 ± 0.41) than younger girls (-1.34 ± 0.21) (p = 0.01). In 10 girls who had already adult height after termination of GH treatment BMD was assessed and factors were investigated which influenced it. In all girls puberty was induced pharmacologically. Their z-score of BMD-CA before GH treatment was -3.81 ± 0.66 SDS and after 3.50 ± 0.5 years of GH administration it increased significantly to -1.02 ± 0.21. After completion of GH treatment BMD correlated with height (r2 = 0.64, p = 0.005) but not with age at the onset of GH treatment, period of GH treatment, age at onset of oestrogen substitution nor with the duration of combined oestrogen-gestagen treatment. The correlation with the age of menarche was at the borderline of significance (r2 = 0.48, p = 0.05). The results indicate that assessment of BMD by the DEXA method expressed in g/cm2 in girls with Turner’s syndrome (as well as in other children with impaired growth and/or bone maturation) must be correlated to bone age or even better to height age and not to chronological age. It would be best to use volumometric densitometry the results of which are not influenced by height.

        Key words: Turner’s syndrome, bone mineral density, growth hormone treatment