Evaluation of growth hormone secretion after completion of therapy

Growth hormone (GH) reserve in young adults previously diagnosed as having GH insufficiency, who were treated with human (h)GH replacement in childhood needs confirmation in adulthood.

Nine patients (seven males, two females; two empty cella, one hypoplasia of the hypophysis and six with idiopathic GH deficiency) diagnosed as having GH insufficiency by the insulin tolerance test (ITT) and dopamine stimulation test in childhood (mean age 12.8+/-2.6 years) were retested at completion of linear growth (mean age 21.0+/-3.0 years), 4.6+/-1.6 years after discontinuation of hGH therapy.

At the initial diagnosis, seven had complete and two had partial GH deficiency. At diagnosis, the mean peak GH response to ITT and dopamine was 4.8+/-4.08 and 3.4+/-2.9 mU/L, respectively. At retesting, the mean GH response to ITT and dopamine stimulation was 3.5+/-2.5 and 3.3+/-3.1 mU/L, respectively (P=0.91 and 0.96, respectively). During hGH therapy, mean height velocity increased from 3.5+/-1.9 cm/year at diagnosis to 9.9+/-3.64 cm/year during the first year (P=0.002). One of nine children diagnosed as having GH insufficiency who was treated with hGH replacement had normal growth hormone secretion at completion of linear growth.

All GH-insufficient children should be retested after completion of their hGH treatment and linear growth to identify those who are truly GH insufficient and who may benefit from GH therapy in adulthood.