About 10% of short patients referred for endocrine consultation have hypopituitarism. This may be in the form of growth hormone deficiency in association with the loss of other pituitary trophic hormones or isolated growth hormone deficiency. For treatment of these patients, pediatricians inquire whether human growth hormone (HGH) is available and what growth response will result from its administration.
Excellent responses in augmenting somatic growth and controlling hypoglycemia in the treatment of growth hormone deficiency have been obtained with intramuscular injections of HGH. Growth rates increase to supranormal levels, permitting "catch up" growth in amounts as much as 15 cm per year during therapy. It is frequently necessary to treat with HGH for several years, since the hypopituitary patient is usually well below the 3rd percentile in height at the time of diagnosis. The minimum amount of HGH required would at present seem to be of the order of 3 units per week. Since most HGH preparations have a potency of the order of 1 unit or less per milligram, and the human pituitaries from which HGH is extracted yield from 3 to 5 mg (depending on the extraction procedure), many pituitaries are required to treat each patient.
The increasing availability of growth hormone immunoassay has made it possible to diagnose growth hormone deficiency relatively easily; therefore, the number of children who need therapy has increased considerably. However, the supply of growth hormone is still entirely dependent on the collection and extraction of human pituitaries. This laborious procedure has not been able to keep up with the increasing demand for the hormone.