Editor,—Drs Garden and Davidson raise some very important points concerning the best oestrogen preparation for long term replacement in ovarian failure.1 Their comments are principally directed at oestrogen replacement during adulthood rather than pubertal induction. The latter is most easily effected using ethinyl oestradiol, because suitable low dose preparations are available so that puberty can be induced gradually over several years. The issue of which oestrogen preparation should be used for long term replacement in patients with hypogonadism is relevant not only to girls with galactosaemia but also to those with Turner's syndrome and hypopituitarism. The recommendation to use a combined oral contraceptive preparation in a young woman who has completed pubertal induction is based on practicality and convenience to the user.

The problem when choosing an oestrogen preparation once full pubertal development has been achieved is that there is a paucity of evidence to inform decision making. Although empirical dose equivalents of ethinyl oestradiol versus conjugated oestrogen or natural oestrogen are available, these values have not necessarily been defined on criteria such as the efficacy in maintaining secondary sexual development or in inducing acquisition of bone mass rather than prevention of osteoporosis. Development of peak bone mass will be very important to women in their late teens or early 20s.

It is clear that randomised studies of different oestrogen preparations in young women who have been induced through puberty are a priority. Until results are available, then either a combined oral contraceptive preparation or a hormone replacement treatment would be acceptable.