Bone mineral density and body composition in short children born SGA during growth hormone and gonadotropin releasing hormone analog treatment.

CONTEXT: Postponement of puberty by GnRH analog (GnRHa) in addition to GH treatment might increase adult height (AH) in short adolescents born small for gestational age (SGA). GnRHa treatment is thought to have negative effects on bone mineral density (BMD) and body composition.

OBJECTIVE: The objective of the study was to assess the BMD of total body (BMD(TB)), lumbar spine (BMD(LS)), bone mineral apparent density lumbar spine (BMAD(LS)), lean body mass, fat mass, and fat distribution during GH treatment, with or without an additional 2 yr of GnRHa.

PATIENTS AND DESIGN: This was a prospective GH trial involving short SGA adolescents (≥8 yr). Eighty-eight children (50 girls) were treated until AH (GH randomized 1 or 2 mg/m(2) · d during puberty); 52 of these children received additional GnRHa. BMD and body composition were longitudinally assessed by dual-energy X-ray absorptiometry.

RESULTS: Baseline BMD(TB) sd score (SDS) and BMD(LS) SDS were significantly reduced (both P < 0.001), but BMAD(LS) SDS was comparable with zero (P = 0.129). BMD(TB) SDS and BMD(LS) SDS improved (both P < 0.001) from the start until AH, whereas BMAD(LS) SDS remained similar (P = 0.168). At AH, 93% of patients had a normal BMD(TB), 99% a normal BMD(LS), and 98% a normal BMAD(LS) (> -2 and < +2 SDS). From the start until AH, lean body mass SDS(height) and fat mass SDS increased significantly toward zero (both P <0.001). Multiple regression analyses showed that additional GnRHa treatment had no adverse effect on the changes in BMD and body composition during GH treatment, also after correction for influencing variables.

CONCLUSION: Untreated short SGA adolescents had reduced BMD(TB) and BMD(LS) but normal bone size-corrected BMAD(LS). During GH treatment, BMD(TB) and BMD(LS) increased significantly, leading to a normal adult BMD in almost all patients. Two years of GnRHa in addition to GH treatment had no adverse effect on BMD or body composition.