Methods for evaluation of growth in Turner's syndrome: critical approach and review of the literature.

Patients with Ullrich-Turner syndrome (UTS) are treated increasingly with growth hormone (GH) to improve growth velocity and final height. For evaluation of the effectiveness of this treatment, different methods have been applied and we demonstrate that the results depend, to some extent, on the specific method that has been used for analysis of data. We have analysed height and growth velocity data as well as the applied methodology from 13 studies on spontaneous growth in UTS. Most studies were based on calculations of annual means or medians of data collected in a longitudinal/cross-sectional manner; others used mathematical models. Growth velocities were calculated longitudinally in individual patients or were derived from height curves graphically or mathematically. Individual height data for a given age varied between 2.6 and 7.7 cm, when estimated annual means were applied, and between 0.4 and 5.8 cm when mathematical models were used. Reported data on growth velocity were almost identical in all studies except for the age of expected puberty, when some authors found a minor pubertal growth spurt. Standard deviations for growth velocity increased at the time of pubertal age and amounted to up to 70% of the respective growth velocity. When various UTS height standards were applied for evaluation of treatment effects, we found a difference of up to 100% of the SD score due to the different SD values of reference data. Results expressed as height SD score may be biased by relatively low mean heights of reference data at adolescent ages.