A longitudinal study on bone mineral density until adulthood in girls withTurner's syndrome participating in a growth hormone injection frequency-response trial

OBJECTIVE The aim of this study was to assess the volumetric bone mineral d ensity (BMD) in girls with Turner's syndrome (TS) before and during growth hormone (GH) treatment in combination with low dose oestrogens as well as t hree years after discontinuation of GH treatment. DESIGN In a prospective, randomized injection frequency-response study, the effect of GH treatment in combination with low dose ethinyl oestradiol (st arting with 0.05 mu g/kg/day), on BMD was evaluated, comparing twice daily (BID) with once daily (OD) injections of a total GH dose of 6 IU/m(2)/day u ntil adult height was reached. After discontinuation of GH treatment, the d osage of oestrogens was further increased to adult supplementation levels. PATIENTS Nineteen untreated girls with TS, mean (SD) baseline pretreatment age 13.3 (1.7) (range 11.0-17.6) year, MEASUREMENTS Before and during GH treatment, measurements of volumetric BMD were performed using phalangeal radiographic absorptiometry, In addition, the BMD measurements were repeated three years after discontinuation of GH treatment. BMD results were adjusted for bone age and sex, and expressed as SD-scores (SDS) using reference values of healthy Dutch girls. RESULTS At baseline, most individual BMD values of cortical bone as well as those of trabecular bone were within the normal range of healthy girls. Ho wever, the mean BMD SDS of the trabecular bone was significantly lower than zero. During treatment, the BMD SDS showed a significant increment to valu es equal or higher than zero after mean (SD) GH treatment period of 36.6 (7 .5) months. The increase in BMD of the cortical bone was significantly high er in the OD group than in the BID group. The BMD SDS in the last year of G H treatment was not significant different between the two injection frequen cy groups. Three years after discontinuation of GH treatment, the BMD value s had increased further similar as in healthy girls, resulting in BMD value s all within normal range or even higher. CONCLUSIONS Most untreated girls with Turner syndrome, age greater than or equal to 11 years, have a normal volumetric BMD of the cortical, as well as of the trabecular bone compared to healthy girls. During GH treatment with 6 IU/m(2)/day in combination with low dose oestrogens, the BMD SDS increas es significantly. After discontinuation of GH treatment and the use of oest rogens in an adult dosage, the BMD was as high as in young healthy women.