To minimize the rate of side-effects, a retrospective analysis of 28 studies of GH replacement therapy in adults indicates that the maintenance dose should usually not exceed 1.0 IU/m2/day (about 1.5-2.0 IU/day) in GHD patients 40-60 years old, or 1.5 IU/m2/day (about 2.5-3.0 IU/day) in GHD patients 20-40 years old. GHD women may tolerate, and in fact may need, higher replacement doses, though this issue requires further investigation. GH treatment should be started at a low dose, i.e. about 1.0 IU/day, and increased gradually, by about 0.5 IU per month, until the target dose is reached. In the absence of side-effects, the GH dose may be either too low, adequate, or too high. Measurement of GH-dependent serum markers provides the most promising approach to detect both GH depletion and excess, with serum IGF-I concentration the current method of choice. Clinical awareness of symptoms of GH excess remains important, however, particularly in patients with IGF-I levels in the high normal range.