Changes, limitations, and prospects of adult height in GH treatment for Japanese GHD patients

For the treatment of pituitary dwarfism (called pituitary short stature in 1987 and renamed as growth hormone deficiency [GHD] in 1993), pituitary-derived human growth hormone (phGH) was approved in 1975, and recombinant hGH (rhGH) was approved in 1988. Adult height in patients with isolated GH deficiency (IGHD) improved by 2000. However, this improvement was mainly due to the increase in height SDS at treatment initiation. Although the mean adult height in patients with idiopathic GHD has been reported to be approximately –1.0 SD or higher in Europe and the United States, the mean adult height of patients with idiopathic GHD in Japan has not improved as much as that in Europe and the United States after 2000. The possible reasons were: low therapeutic doses than those in Europe and the United States; changes in background factors, such as reduction in severe GHD; differences in response to GH between Caucasians and Japanese; and, no increase in height at puberty onset because delayed puberty was normalized by GH treatment. In the future, long-acting GH is expected to improve adult height in GHD patients in Japan.