Down Syndrome Abstract
of the Month:
May 1999
Growth hormone treatment in young children with Down's syndrome: effects on growth and psychomotor development.
Anneren G, Tuvemo T, Sara VR, et al.
Arch Dis Child 1999; 80:334-338
Dept. of Genetics, Uppsala Univ. Children's Hospital, Sweden; and Centre for Molecular Biotechnology, Brisbane, Australia
Abstract:
Background -- Learning disability and short stature are cardinal signs of Down's syndrome. Insulin-like growth factor I (IGF-I), regulated by growth hormone (GH) from about 6 months of age, may be involved in brain development.Aims -- To study long term effects of GH on linear growth and psychomotor development in young children with Down's syndrome.
Study design -- Fifteen children with Down's syndrome were treated with GH for three years from the age of 6 to 9 months (mean, 7.4). Linear growth, psychomotor development, skeletal maturation, serum concentrations of IGF-I and its binding proteins (BPs), and cerebrospinal fluid (CSF) concentrations of IGF-II were studied.
Results -- The mean height of the study group increased from -1.8 SDS (Swedish standard) during treatment, whereas that of a Down's syndrome control group fell from -1.7 to -2.2 SDS. Growth velocity declined after treatment stopped. Head growth did not accelerate during treatment. No significant difference in mental or gross motor development was found. The low concentrations of serum IGF-I and IGFBP-3 became normal during GH treatment.
Conclusions -- GH treatment results in normal growth velocity in Down's syndrome but does not affect head circumference or mental or gross motor development. Growth velocity declines after treatment stops.
My comments:
The abstract speaks for itself, but here are some other items from the study:The children with DS were started on GH treatment between 6 and 9 months of age. At no point did any child have abnormalities in their blood cell tests; however, a sixteenth child was dropped from the project after some liver tests were found to be abnormal. These liver tests came back to normal after treatment was stopped.
The lack of effect of GH on head circumference is in opposition to the study by Torrado in 1991. The authors did not attempt to explain this discrepancy.
IGF-I and IGF-II are both noted to stimulate neuron development. Only IGF-II is detectable in the CSF, which explains why they only looked for that one. IGF-I has a neuroprotective role and has been suggested as a therapeutic agent for neurodegeneration. GH, produced in the pituitary gland of the brain, regulates IGF, but it is not known whether or not injected GH affects IGF in the brain.
The authors close with this quote: "At present, we and others do not recommend GH treatment of children with Down's syndrome without proven GH deficiency."