Muscle Function Improves during Growth Hormone Therapy in Short Children Born Small for Gestational Age: Results of a Peripheral Quantitative Computed Tomography Study on Body Composition

• Published in: The journal of clinical endocrinology and metabolism Vol. 93; no. 8; pp. 2978 - 2983
• Main Authors: Schweizer, Roland, Martin, David D., Schönau, Eckhard, Ranke, Michael B.
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Endocrine Society 01.08.2008
• Subjects: Biological and medical sciences; Body Composition; Body Height - drug effects; Body Mass Index; Child; Child, Preschool; Endocrinopathies; Feeding. Feeding behavior; Female; Fundamental and applied biological sciences. Psychology; Growth Disorders - drug therapy; Growth Disorders - physiopathology; Human Growth Hormone - deficiency; Human Growth Hormone - therapeutic use; Humans; Infant, Newborn; Infant, Small for Gestational Age; Male; Medical sciences; Muscle Strength; Muscle, Skeletal - physiology; Tomography, X-Ray Computed; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vertebrates: endocrinology; Intrauterine growth retardation; Pregnancy disorders; Hormone therapy; Birth; Body composition; Result; Fetal diseases; Improvement; Muscle; Child; Nutritional status; Quantitative analysis; Human; Obesity; Radiodiagnosis; Nutrition; Nutrition disorder; Low birth weight; Metabolic diseases; Somatotropin; Newborn diseases; Adenohypophyseal hormone; Prematurity; Medical imagery; Computerized axial tomography; Hormone replacement therapy; Endocrinology
• ISSN: 0021-972X; 1945-7197
• DOI: 10.1210/jc.2007-2600

Background: Short small for gestational age (SGA) children can be affected by a lack of muscle mass rather than fat mass. They also face a high risk of the metabolic syndrome developing after childhood. It is not known whether low muscle mass influences muscle function. Aim: Our aim was to investigate muscle-fat distribution and muscle function before and during GH treatment in short SGA children. Patients: A total of 34 prepubertal short SGA children (11 females, seven with Silver-Russell syndrome) were included in the study. Mean values were: age at GH start 7.3 yr; height sd score (SDS) −3.3; and birth weight SDS −2.7. Methods: Investigations over 24 months on GH treatment (57 μg/kg·d) were performed. Body composition, including fat area and muscle area (MA), was assessed through peripheral quantitative computed tomography (XCT 2000; Stratec, Inc., Pforzheim, Germany). Maximal isometric grip force was performed with a Jamar dynamometer (Preston, Jackson, MI). Comparison with height-dependent reference values (SDSHeight) was calculated. Results: MA SDSHeight at GH start was −1.8 and increased to −0.8 (P < 0.001) and −0.8, and fat area SDSHeight decreased from −0.6 to −2.0 (P < 0.001) and −1.5 after 12 and 24 months on GH. Maximal isometric grip force SDSHeight increased from −0.9 to 0.3 (P < 0.001) and 0.5. MA at start correlated negatively with height velocity (R = −0.54; P < 0.001) and MA SDS at start and Δ-height SDS during the first year of GH treatment (R = −0.40; P < 0.001). Conclusions: Short stature in SGA children is associated with low muscle mass and function. Supraphysiological GH doses led to a concomitant increment in height, muscle mass, and function, whereas fat mass decreased. Furthermore, body composition at GH start gives insight into GH responsiveness and the individual risk of metabolic syndrome.