Impact of non-weight-dependent low-dose somatropin on bone accrual in childhood-onset GH deficient in the transition: an 18-month randomized controlled trial

Objective: Discontinuation of growth hormone therapy (rhGH) upon completion of linear growth may adversely affect bone mineral density and content (BMD/BMC) in adolescents with childhood-onset GH deficiency (CO-GHD) and predisposition to osteoporosis. Although the benefits of weight-dependent somatropin high doses over bone gain are established, little is known about fixed low doses. We analyzed the impact of non-weight-based low-dose somatropin on bone accrual during the transition among CO-DGH patients, treated since childhood.

Methods: Lumbar spine (LS) and whole-body (WB) BMD and BMC were measured at baseline and after 18 months in 54 adolescents (age: 16.8 ± 1.6 years). They were retested and reclassified as GH sufficient (GHS, n = 28) and GH insufficient. The last group was later randomized to use rhGH (GH on; n = 15) or no treatment (GH off, n = 11) in this single-center open-label study. The average dose of rhGH was 0.5 ± 0.18 mg/day.

Results: When comparing the groups, the GH off group had a lower percentage change in LS BMD than the GHS (0.53 % ± 5.9 vs. 4.42 % ± 4.1, respectively, p < 0.04). However, in the analysis of the GH on and off subgroups, the LS BMC percentage change was higher in the GH on (11.02 % ± 10.12 vs. 2.05 % ± 10.31, respectively, p < 0.04).

Conclusion: Non-weight-based low-dose somatropin withdrawal for 18 months limits bone accrual in LS of CO-DGH subjects in transition, predisposing them to osteoporosis in adult life.