An audit of oestradiol levels and implant frequency in women undergoing subcutaneous implant therapy.

Objectives: The aim of the study was to review our long-term use of subcutaneous oestradiol (E2) implant therapy for the treatment of climacteric symptoms in post-menopausal women. On the grounds that the aim is to restore premenopausal serum E2 levels, our declared clinical policy is not to repeat implants even in the presence of symptoms if serum E2 levels are > 400 pmol/l. Therapy was with 50 mg E2 implants inserted subcutaneously in the lower abdominal wall.

Design: All women who had attended the gynaecological/endocrinological clinic who had received subcutaneous E2 implants for the relief of climacteric symptoms between December 1981 and 1992 were included.

Results: Between December 1981 and December 1992, 275 women received a total of 759 50 mg E2 implants. The median length of implant therapy was 34.2 months (range 3.7-109.5 months), and the median number of implants per patient was 4 and ranged from 1 to 13. One hundred and twenty-nine women had more than four implants and their mean recorded serum E2 level was 425 +/- 187 (mean +/- SD) pmol/l; the mean level over the first 24 months of therapy was 408 +/- 157 pmol/l. This was not different from the mean value of the remaining period of therapy (439 +/- 168 pmol/l). Following the second implant there was no significant progressive rise in serum E2 with time and implant number and the mean E2 level per patient was no higher in those patients who received implants more frequently. The mean time between the first two implants was 9.7 +/- 0.4 months and between subsequent ones was 11.7 +/- 0.5 months. After the first two implants there was no progressive change in this interval with time.

Conclusion: This study shows that effective, safe and sympathetic management of women with oestrogen deficient symptoms may be achieved by use of two criteria to determine re-treatment; the return of symptoms, and a serum E2 level no higher than 400 pmol/l. Once therapy is established, E2 implants may need to be prescribed only on an annual basis. There appears to be no justification for giving E2 implants more frequently as this policy achieves satisfactory (physiological) premenopausal E2 levels and good symptomatic relief without any evidence for accumulation of E2 or 'tachyphylaxis'.