No abstract

In skeletal muscle and tendon the extracellular matrix confers important tensile properties and is crucially important for tissue regeneration after injury. Musculoskeletal tissue adaptation is influenced by mechanical loading, which modulates the availability of growth factors, including growth hormone (GH) and insulin-like growth factor-I (IGF-I), which may be of key importance. To test the hypothesis that GH promotes matrix collagen synthesis in musculotendinous tissue, we investigated the effects of 14 day administration of 33-50 μg kg −1 day −1 recombinant human GH (rhGH) in healthy young individuals. rhGH administration caused an increase in serum GH, serum IGF-I, and IGF-I mRNA expression in tendon and muscle. Tendon collagen I mRNA expression and tendon collagen protein synthesis increased by 3.9-fold and 1.3-fold, respectively (P < 0.01 and P = 0.02), and muscle collagen I mRNA expression and muscle collagen protein synthesis increased by 2.3-fold and 5.8-fold, respectively (P < 0.01 and P = 0.06). Myofibrillar protein synthesis was unaffected by elevation of GH and IGF-I. Moderate exercise did not enhance the effects of GH manipulation. Thus, increased GH availability stimulates matrix collagen synthesis in skeletal muscle and tendon, but without any effect upon myofibrillar protein synthesis. The results suggest that GH is more important in strengthening the matrix tissue than for muscle cell hypertrophy in adult human musculotendinous tissue.

IGF-I-based GH dosing is clinically feasible and allows maintaining serum IGF-I concentrations within the desired target range. Titrating the GH dose to achieve higher IGF-I targets results in improved growth responses, although at higher average GH doses.

IGF-based GH dosing is clinically feasible in both GHD and ISS patients, although GH dose requirements and auxological outcomes are distinct between these groups. This suggests a degree of both GH and IGF insensitivity in subjects with ISS that requires specific management strategies to optimize growth during GH therapy.

Based on the increasing body of evidence that adults with GH deficiency (somatotropin deficiency) have impaired health that improves with GH replacement, many countries have already approved the use of GH for replacement therapy in adults with GH deficiency. To ensure that patients are appropriately identified and treated, the Growth Hormone Research Society (GRS) convened a workshop on April 14-17, 1997, in Port Stephens, Australia, to formulate consensus guidelines for the diagnosis and treatment of adults with GH deficiency. The GRS invited scientists with expertise in the field, representatives from industry involved in the manufacture of recombinant human GH, and representatives from health authorities from a number of countries to attend the workshop, all of whom contributed to the consensus guidelines as detailed below.

Normal growth is a sign of good health. Monitoring for growth disturbances is fundamental to children's health care. Early detection and diagnosis of the causes of short stature allows management of underlying medical conditions, optimizing attainment of good health and normal adult height.ConclusionThis review summarizes currently available information on monitoring for short stature in children and conditions usually associated with short stature and summarizes the authors’ conclusions on the early recognition of growth disorders.

No abstract

Noonan syndrome is a genetic disorder associated with short stature. We reviewed 15 studies in which growth hormone (GH) therapy was used in children with Noonan syndrome. Data show consistent increases in mean height standard deviation score (SDS), with first-year changes of up to 1.26 SDS. Among studies reporting adult or near-adult height, GH therapy over 5-7 years resulted in adult height SDS from -0.6 to -2.1, with up to 60% of subjects in some studies achieving adult height within 1 SDS of mid-parental height. GH treatment results in an acceleration of bone age, likely reflecting normalization from the retarded bone age common in Noonan syndrome patients at the start of therapy. BMI is not affected by GH treatment, but favorable changes in fat mass and body composition are achievable. Longer-term studies and observational studies suggest a waning of the effect of GH therapy over time, as is seen in other GH-treated conditions, and early initiation of therapy and prepubertal status are important predictors of response. GH treatment does not appear to be associated with adverse cardiac or metabolic effects, and data on malignancy during GH treatment give no cause for concern, although they are limited.