An audit of oestrogen implant hormone replacement therapy

The aim of this review was to determine the factors that impact upon oestradiol levels in patients receiving oestradiol implants and to assess the relationship between symptom scores and oestradiol levels. In addition we sought to determine the incidence of tachyphylaxis (menopausal symptoms in spite of high oestradiol levels) among our patients, and to assess the degree of menstrual cycle control in the nonhysterectomized women receiving implant treatment. We undertook an audit of the medical records of 118 women who received 673 oestradiol implants (50 or 100 mg) over an 8-year period in the menopause clinics at Royal North Shore Hospital. Data on patient age, clinical diagnosis, symptom score, previous or subsequent hysterectomy, oestradiol implant dosage (50 mg or 100 mg), number of doses, oestradiol levels and concurrent testosterone implant insertion were recorded. We found that implant dosage (p<0.001) and implant number (p<0.001) were the factors that significantly impact upon oestradiol levels. Concomitant testosterone implant usage (p=0.74), patient age (p=0.14) and hysterectomy (p=0.57) did not have a statistically significant effect upon oestradiol levels. The incidence of tachyphylaxis was 1.7% (2 patients). There was no relationship between oestradiol levels and symptom scores (p=0.69). Oestradiol implant treatment, when administered on the basis of return of symptoms, without a strict target oestradiol level, results in a steady increase in baseline oestradiol levels. The dosage used and the number of implants received are important factors influencing oestradiol levels. The incidence of tachyphylaxis is low when patients are counselled regarding the lack of agreement between symptom scores and oestradiol levels.