The purpose of the study is to measure the functional effects of recombinant GH in skeletal muscle, in addition to growth promotion, in short prepubertal boys with either growth hormone deficiency or idiopathic short stature. Patients will be similarly short. The investigators will also compare these values in the short stature cohort to those obtained in testing performed in normally growing age-matched healthy control boys not on GH. The group on GH will be studied before and after 6 and 12 months of GH treatment.
Prepubertal boys with significant short stature (height SDS ≤-2.0) diagnosed with either GH deficiency or idiopathic short stature (ISS) who are identified as candidates for GH treatment will recruited. Subjects will have a battery of studies to assess skeletal muscle strength, agility, power and endurance, as well as assessment of body composition and energy expenditure before and after GH administration. GH (Somatropin) treatment at standard doses will be given as daily injections at bedtime. Subjects will be followed at three-month intervals per the clinical routine, when anthropometric measurements will be obtained. Baseline studies will be repeated at 6 and 12 months from initiation of treatment, each patient will serve as his own control pre and post GH. A group of normally statured healthy boys will have the same testing as the study patients but without GH treatment to assess the impact of natural growth on the muscle measures above.
Study Type
OBSERVATIONAL
Enrollment
45
Boys with short stature will be studied for measures of: 1. skeletal muscle strength, power, and endurance 2. muscle agility 3. lean body mass accrual 4. bone mineral density and resting energy expenditure before and after 6 months and 12 months of GH administration
Nemours Children's Clinic
Jacksonville, Florida, United States
Skeletal muscle strength (Newtons)
Upper and lower body muscle strength will be assessed using a handheld dynamometer for manual muscle testing of peak force
Time frame: 12 months
Skeletal muscle power (Watts)
Lower extremity power will be assessed by vertical jump performed using a Power time mat
Time frame: 12 months
Muscle agility (seconds)
Muscle agility will be assessed by a timed shuttle run
Time frame: 12 months
Muscle endurance
Upper body muscular endurance will be assessed using a modified push up test for repetitions
Time frame: 12 months
Lean body mass accrual
Assessed by dual energy x-ray absorptiometry (DEXA) scan of the whole body
Time frame: 12 months
Bone mineral density
Assessed by DEXA scan of the lumbar spine and whole body
Time frame: 12 months
Resting energy expenditure
Indirect calorimetry will be performed after overnight fast
Time frame: 12 months
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