Converging Growth Trajectories During Recombinant Human Growth Hormone Therapy in Children With Isolated and Combined Pituitary Hormone Deficiency

ABSTRACT Objective Growth hormone deficiency (GHD) is an important cause of growth failure in children. Although recombinant human growth hormone (rhGH) promotes catch‐up growth, longitudinal differences in treatment response between isolated growth hormone deficiency (IGHD) and combined pituitary hormone deficiency (CPHD) remain unclear. This study compared longitudinal growth trajectories during rhGH therapy between IGHD and CPHD patients. Design and Patients A retrospective cohort study included 72 IGHD and 48 CPHD patients. Measurements Height standard deviation score (SDS) was assessed at baseline and after 12, 24, 36 and 48 months of rhGH therapy. Longitudinal trajectories were analysed using linear mixed‐effects models adjusted for age at treatment initiation, bone age, BMI SDS and pituitary MRI findings. Results CPHD patients had more severe growth impairment at baseline than those with IGHD (height SDS: −5.00 ± 1.57 vs. −3.20 ± 1.12; p < 0.001). However, CPHD demonstrated greater catch‐up growth, achieving larger cumulative height SDS gains after 48 months (3.10 ± 1.36 vs. 1.92 ± 0.87 SDS; p < 0.001). Mixed‐effects modelling confirmed significantly different longitudinal growth trajectories (time‐by‐diagnosis interaction: χ 2 = 66.62, p < 0.001). Adjusted height SDS improved from −3.40 to −1.49 in IGHD and from −4.56 to −1.55 in CPHD. At 48 months, the adjusted CPHD–IGHD difference was −0.06 SDS (95% CI, −0.63 to 0.51), consistent with substantial convergence of the two growth trajectories. Older age at treatment initiation and abnormal pituitary MRI findings were independently associated with lower height SDS across follow‐up. Conclusions Despite more severe baseline growth impairment, children with CPHD experienced greater catch‐up growth during rhGH therapy, resulting in substantial convergence of longitudinal height SDS trajectories toward those of children with IGHD over 4 years.