Growth hormone (GH) therapy is most likely to be of benefit in children with a true GH deficiency who are of a younger age, are significantly short, have significantly delayed skeletal maturation and are growing slowly. Guyda reviews what has been achieved after 40 years of GH therapy in children.
The author notes that long-term growth scores achieved by GH therapy are impressive, although the final height of GH-deficient patients is still short. Studies indicate that the greatest height gain occurs in GH-deficient patients who are younger and have the greatest height deficit when treatment is initiated.
The use of GH therapy in normal children with short stature (idiopathic short stature) has been found to provide a moderate acceleration of growth, resulting in a final height just above the initial prediction. While potential psychologic dysfunction as a result of shortness has been raised as a justification for the use of GH in children with idiopathic short stature, studies have revealed no association between short stature and clinically significant psychologic morbidity. The American Academy of Pediatrics has recommended caution in the use of GH therapy for this purpose, concluding that GH has not been proved useful in increasing the final height of children with growth disorders other than growth failure related to GH deficiency.
Studies show that GH supplementation in girls with Turner syndrome significantly increases the final height. The mean final height in 2,217 girls with Turner syndrome was 150.0 cm, which was 5.7 cm above the projected adult height. Considerable variability in response was noted, however. The effects on psychologic function remain to be determined.
In children born with intrauterine growth retardation or who are small for gestational age, GH administered early (before five years of age) may normalize height during childhood, but it does not result in significant height gain in adulthood.
Side effects of GH therapy include pseudo-tumor cerebri, slipped capital epiphysis, fluid retention and carpal tunnel syndrome. Of the approximately 8,000 patients who received natural GH between 1963 and 1985 in the National Hormone and Pituitary Program, 22 may have developed Creutzfeldt-Jakob disease. Recombinant GH has proved to be safer than natural hormone.
The author summarizes his commentary by noting that children often expect to achieve normal adult height but, unfortunately, the majority of patients with classic GH deficiency, idiopathic short stature or Turner syndrome who are treated with GH do not achieve median normal adult height. However, an increase in height is frequent, and response to GH therapy can be optimal in some patients. The usefulness of GH supplementation in the “normal short child” is questionable because of the lack of clear long-term benefit on psychologic state or final height and the potential negative effect of unfulfilled expectations. Further study is needed to determine precisely which short children, including those with Turner syndrome, will benefit from GH therapy.