6877 Withdrawing Growth Hormone Treatment at Mid-Puberty in Idiopathic Isolated Growth Hormone Deficiency: Baseline Characteristics in Patient-Preference Design Study

Abstract Disclosure: J. Vliegenthart: None. J. Wit: None. B. Bakker: None. A. Boot: None. C. de Bruin: None. M. Finken: None. J.V. Heyden: None. M. Houdijk: None. H. van der Kamp: None. E. Van Mil: None. A. Reedijk: None. T. Sas: None. D.A. Schott: None. P. van Setten: None. S. Straetemans: None. V. van Tellingen: None. B. Touwslager: None. A.V. Trotsenburg: None. P. voorhoeve: None. A.C. Hokken-Koelega: None. D.C. van der Kaay: None. Background: The majority of children diagnosed with idiopathic isolated growth hormone deficiency (IIGHD) show a normal growth hormone (GH) secretion (assessed by GH stimulation tests) when retested at near adult height (NAH). It appears plausible that, if normal stimulated GH secretion is observed in mid-puberty, continuing recombinant human GH (rhGH) treatment may only have a minor effect on NAH. The effect on NAH has never been investigated in a prospective study. Aim: To evaluate patient preference in the choice to (dis-)continue GH treatment from mid-puberty, and to study whether patients who discontinued treatment differed in baseline characteristics from those who continued treatment. Methods: The study population consisted of adolescents who were diagnosed in childhood with IIGHD (GH peak at diagnosis between 1.7 ug/L and 10 ug/L) and who had started rhGH therapy between 2005-2018. According to the national treatment protocol, GH secretion was retested in mid-puberty (males: Tanner stage G3/4, testicular volume 12 ml and bone age (BA) 13-16 years; females: Tanner stage B3/4 and BA 11-14 years). In this multicentre prospective patient-preference design study, adolescents who tested GH sufficient at mid-puberty (GH peak 6.7 ug/L) had the choice to discontinue or continue rhGH treatment until NAH (height velocity 2cm/year). Results: In total 127 patients (95 male, 75%) participated in this study. Forty-four patients (35%) chose to continue GH treatment until NAH (group 1), and 83 patients (65%) chose to discontinue GH treatment (group 2). Mean height at inclusion (group 1: -0.76±0.69 SDS vs group 2: -0.47±0.85 SDS; P=0.055), target height SDS (group 1: -0.73±0.54 SDS and -0.58±0.53 SDS, P=0.15) and age at inclusion (group 1: 14.0±1.1y and 13.9±1.1y, P=0.69) did not significantly differ between groups. Males and females did not differ in these characteristics. Currently, 109 patients (86%) have reached NAH. Conclusions: The majority of patients (65%) preferred to discontinue rhGH treatment after sufficient GH retesting in mid-puberty. An anticipated difference in baseline data between the groups (adolescents who choose to discontinue treatment may be taller and older) could not be confirmed. Data are being collected until all patients reach near adult height. Presentation: 6/3/2024