CONTEXT: Girls with Turner syndrome (TS) suffer linear growth failure, and TS is a registered indication for growth hormone (GH) treatment. GH is classically dosed according to body weight, and serum insulin-like growth factor-1 (IGF-1) concentrations are recommended to be kept within references according to international guidelines.

OBJECTIVE: To assess the effect of long-term GH treatment in girls with TS following GH dosing by IGF-1 titration.

DESIGN AND SETTING: A retrospective, real-world evidence, observational study consisting of data collected in a single tertiary center from 1991 to 2018.

PATIENTS: A cohort of 63 girls with TS treated with GH by IGF-1 titration with a median duration of 6.7 years (interquartile range [IQR]: 3.4-9.7 years).

MAIN OUTCOME MEASURES: Longitudinal measurements of height, IGF-1, and adult height (AH) following GH treatment were evaluated and compared between the different karyotypes (45,X, 45,X/46,XX, or miscellaneous).

RESULTS: Using GH dose titration according to IGF-1, only 6% of girls with TS had supranormal IGF-1 levels. Median dose was 33 µg/kg/day (IQR: 28-39 µg/kg/day) with no difference between the karyotype groups. AH was reached for 73% who attained a median AH of 1.25 standard deviation score (SDS) for age specific TS references (IQR: 0.64-1.50 SDS), and a median gain in height (ΔHSDS: AH SDS minus baseline height SDS of TS references) of 0.50 SDS, equal to 3.2 cm (SD 7.68) for all karyotypes.

CONCLUSION: Our real-world evidence study suggested that titration of GH dose to keep IGF-1 levels within the normal range resulted in a lower AH gain than in studies where a fixed dose was used.