LAUSR

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 220 to 214 (p<0.05). Cortical density (mg/cm3) increased from 1077 to 1099 (p<0.01) in sGHD patients and from 1060 to 1079 in tGHD patients (p<0.001). The strength strain index (mm3) showed no significant changes in sGHD patients (306 to 310) but changed from 302 to 312 in tGHD patients (p<0.05). Total bone area (mm2) shifted from 145 to 146 in sGHD patients and from 153 to 155 in tGHD patients. Total body aBMD (g/cm2) increased in both groups: from 1020 to 1050 in sGHD patients and from 1022 to 1052 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.