Objective:​ Severe growth hormone deficiency causes lean body mass loss in male adolescents and increased fat mass in both sexes. The changes appear after a 6 month GH pause.

Aim:​ The aim was to examine bone density and structure changes in adolescents with severe GHD during a 6-month rhGH treatment interruption.

Patients and methods:​ In total, 113 adolescents (20 females) paused rhGH treatment for 6 months at near-final height, and they were retested with arginine-GHRH challenge and basal IGF-1. Severe GHD was diagnosed in 19 individuals (5 females, GH peak <16 ng/ml and IGF-1 < −1.9 SDS) and excluded in 94 (15 females). Bone density and structure were measured by pQCT of the forearm and DXA of the total body at cessation of rhGH and 6 months later.

Results:​ In severe adolescent GHD (sGHD) patients, trabecular density (mg/cm³) decreased from 214 to 202 (p < 0.01);​ changes in the adolescents with normal test results (tGHD) were from 221 to 214 (p < 0.05). Cortical density (mg/cm³) increased from 1077 to 1099 (p < 0.01) in sGHD patients and from 1060 to 1082 in tGHD patients (p < 0.001). The strength strain index (mm³) showed no significant changes in sGHD patients (306 to 307) but changed from 302 to 315 in tGHD patients (p < 0.05). Total bone area (mm²) shifted from 145.1 to 145.2 in sGHD patients and from 153 to 156 in tGHD patients. Total body aBMD (g/cm²) increased in both groups:​ from 1.10 to 1.12 in sGHD patients and from 1.11 to 1.14 in tGHD patients (p < 0.01). All bone measurements remained within the reference ranges, and there were no differences between sGHD and tGHD patients.

Conclusion:​ During a 6-month pause of rhGH treatment, the bone structure and density of adolescents with sGHD did not show changes implying harm. Routine retesting of adolescents, including 6 months without GH, is unlikely to be detrimental to the bone.