GH Treatment Effects on Body Composition in SGA

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The use of growth hormone (GH) therapy in small for gestational age (SGA) children with short stature, now approved and licensed both in the US and Europe, requires critical appraisal. Body composition in childhood may be affected by alteration of fetal growth. SGA infants who show catch-up growth tend to become obese and may be at risk for metabolic syndrome in adult life. However, SGA children who remain short are thin and have a low BMI and possibly compromised bone mineral density. The group of 25 SGA subjects (birth weight and current height <–2 SD) reported in this study were prepubertal and randomized to receive either GH therapy (n=16) or act as untreated controls for 3 years and then start GH therapy (n=9). Heights in both groups were <–2 SD and the daily GH dose was 1 mg/m2 body surface area.

Clinical characteristics were comparable in the 2 groups. In the untreated subjects lean body mass (LBM) decreased during the 3 years (P<0.01) contrasting with the GH-treated group which showed catch-up increase of LBM. When the untreated subjects started GH, their LBM SDS also increased significantly. Therefore GH therapy, in the dose described, induced catch-up of LBM. However percentage body fat decreased in the GH-treated subjects. Bone mineral density SDS measured by DEXA increased significantly in the GH-treated group compared to the untreated subjects.

Willemsen RH, Arends NJ, Bakker-van Waarde WM, et al. Long-term effects of growth hormone (GH) treatment on body composition and bone mineral density in short children born small-for-gestational-age: six-year follow-up of a randomized controlled GH trial. Clin Endocrinol (Oxf). 2007;67:485-92.

Editor’s Comment

These findings are of interest, but their clinical relevance remains uncertain. The anabolic effects of GH on muscle bulk and bone mineralization are demonstrated, as is its lipolytic effect. However the benefit to the child of these changes is difficult to assess. Is the improvement in BMD really going to prevent development of osteoporosis and increased fracture risk in adult life? The answers are unknown. Is the reduced LBM in the untreated short SGA child actually a disadvantage to the child? Again we are not certain. However, in this report the carefully studied longitudinal changes in body composition which occur during GH therapy are useful in documenting the anabolic and lipolytic effects of GH in short SGA children.

Martin O. Savage, MD

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Last Updated: 04/30/2008