Effects of Growth Hormone on Glucose and Protein Metabolism in Children With Growth Hormone Deficiency
Summary
The purpose of the proposed study is to investigate the effects of rhGH treatment on glucose, protein and fat metabolism in GHD children. Specifically, we will measure the rates of glucose production, gluconeogenesis, glycogenolysis, insulin sensitivity and glucagon response before and after treatment with rhGH. In addition, we will study changes in protein and fat metabolism pre and post rhGH therapy in children with GHD. The findings in the GHD children will be compared to those of a control group of age and sex matched healthy children.
Hypotheses: H1- The fraction of glucose derived from gluconeogenesis is decreased and that from glycogenolysis is increased in the post-absorptive state in untreated GHD children when compared to healthy children. H2- Treatment with rhGH will not change the overall glucose turnover but will normalize the abnormal partitioning of gluconeogenesis and glycogenolysis in GHD children. H3- GH replacement will reduce urea production and increase estimates of protein synthesis, thus optimizing the availability of amino acids for growth. H4- Untreated children with GHD after an overnight fast will have an increased glucagon challenge response that will decrease after 8 weeks of treatment with rhGH.
Specific Aims: In healthy and newly diagnosed GHD children we will: 1. Measure the Glucose Production Rate (GPR) 2. Determine the fraction of glucose derived from gluconeogenesis and glycogenolysis 3. Estimate insulin sensitivity 4. Measure proteolysis and protein oxidation 5. Determine glucagon challenge response after an overnight fast. The above-mentioned parameters will be re-evaluated in the children with GHD after 8 weeks of rhGH therapy.
Description
Children with growth hormone deficiency (GHD) have increased insulin sensitivity and may present with hypoglycemia during infancy. Treatment with recombinant human growth hormone (rhGH) reduces the risk for hypoglycemia and decreases insulin sensitivity. We hypothesize, that GHD causes a decrease in the fraction of glucose derived form gluconeogenesis and conversely glycogenolysis and insulin sensitivity will be increased, when GHD children are compared to healthy controls. We anticipate that total glucose production will be unaffected by rhGH therapy. Therefore, the GDH subjects treated with rhGH for 8 weeks will have an increase in the fraction of glucose derived form gluconeogenesis and a decrease in that form glycogenolysis and decreased insulin sensitivity. To test this hypothesis, 10 healthy and 10 GHD children will be studied using the stable isotope [U-13C] glucose and Mass Isotopes Distribution Analysis (MIDA). We will be specifically measuring the rate of glucose production, gluconeogenesis, glycogenolysis, insulin sensitivity and glucagon response after an overnight fast. In addition, we will measure changes in protein oxidation, proteolysis and fat metabolism using the stable isotopes [15N2] urea, [1-13C] leucine and concentrations of free fatty acids and b-hydroxybutyrate. The GHD group will be studied at the time of diagnosis and after 8 weeks of rhGH.
Study Design
Allocation: Non-Randomized, Control: Active Control, Endpoint Classification: Pharmacodynamics Study, Intervention Model: Parallel Assignment, Masking: Open Label, Primary Purpose: Diagnostic
Conditions
Growth Hormone Deficiency
Intervention
growth hormone (Nutropin)
Location
Baylor College of Medicine
Houston
Texas
United States
77030
Status
Recruiting
Source
Baylor College of Medicine
Results (where available)
Links
- Source: http://clinicaltrials.gov/show/NCT00362063
- Information obtained from ClinicalTrials.gov on July 15, 2010
Medical and Biotech [MESH] Definitions
Human Growth Hormone
A 191-amino acid polypeptide hormone secreted by the human adenohypophysis (PITUITARY GLAND, ANTERIOR), also known as GH or somatotropin. Synthetic growth hormone, termed somatropin, has replaced the natural form in therapeutic usage such as treatment of dwarfism in children with growth hormone deficiency.
Dwarfism, Pituitary
A form of dwarfism caused by complete or partial GROWTH HORMONE deficiency, resulting from either the lack of GROWTH HORMONE-RELEASING FACTOR from the HYPOTHALAMUS or from the mutations in the growth hormone gene (GH1) in the PITUITARY GLAND. It is also known as Type I pituitary dwarfism. Human hypophysial dwarf is caused by a deficiency of HUMAN GROWTH HORMONE during development.
Laron Syndrome
An autosomal recessive disorder characterized by short stature, defective GROWTH HORMONE RECEPTOR, and failure to generate INSULIN-LIKE GROWTH FACTOR I by GROWTH HORMONE. Laron syndrome is not a form of primary pituitary dwarfism (GROWTH HORMONE DEFICIENCY DWARFISM) but the result of mutation of the human GHR gene on chromosome 5.
Growth Hormone-secreting Pituitary Adenoma
A pituitary tumor that secretes GROWTH HORMONE. In humans, excess HUMAN GROWTH HORMONE leads to ACROMEGALY.
Growth Hormone
A polypeptide that is secreted by the adenohypophysis (PITUITARY GLAND, ANTERIOR). Growth hormone, also known as somatotropin, stimulates mitosis, cell differentiation and cell growth. Species-specific growth hormones have been synthesized.
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