- the optimum level of HRT cannot be established via the measurement of oestradiol or FSH levels
- this is because oestradiol (estradiol) is largely metabolised to oestrone which does not cause a reduction in FSH levels
With respect to measurement of serum estradiol in the menopause transition
It has been noted that where there are ongoing distressing symptoms for women using HRT, clinicians may be tempted to measure a serum estradiol level to attempt to check absorption. Detailed guidance has been developed to highlight issues with respect to measurement of estradiol in the perimenopause (1):
- there is uncertainty about the significance of a single serum estradiol level both in relation to symptom management and in managing long-term
health consequences of the menopause, such as osteoporosis and cardiovascular disease - the clinician should also note that in the perimenopause it is not possible to distinguish between endogenous and exogenous estradiol through serum estradiol testing
- is poor correlation between serum estradiol and symptom management with significant inter-individual clinical response to the same dose of estradiol containing HRT
- is no value in checking serum estradiol if a patient is taking oral estradiol, as a significant percentage is metabolised to the weaker estrone
- is no value in measuring a serum estradiol in women taking combined hormonal contraception
- is no known threshold for serum estradiol and prevention of loss of bone density or prevention of osteoporotic related fractures
- is no evidence regarding the optimum HRT monitoring strategy for women with premature ovarian insufficiency (POI)
- although it is stated that monitoring serum estradiol may be useful in monitoring women with female hypogonadism including POI, but a holistic approach is necessary to ensure adequate treatment
- the ratio of estradiol and estrone change after the menopause, so there is significantly more estrone
- during the menopause transition there is an overall decline in estradiol, but in the perimenopause estradiol can fluctuate erratically and dramatically
- estradiol levels can be supraphysiological at times during the perimenopause
- thought that this is related to an increase in FSH, resulting in a second increase in estradiol during the mid- and late luteal phases, which continues to a peak during the subsequent menstrual phase
- this second rise and fall in estradiol is typical of a normal follicular phase, except that it is superimposed on an existing ovulatory cycle
- is variation of measured serum estradiol for any dose of HRT in any given individual
- measuring a serum estradiol level is particularly unhelpful in patients taking oral estradiol as the main circulatory metabolite is estrone
The review authors (Dr Clare Spencer and Dr Heather Currie, in collaboration with the medical advisory council of the British Menopause Society) note that "If a patient has ongoing symptoms, listening to the patient, providing holistic care and changing HRT to alternative delivery routes may be more helpful strategies than measuring a serum estradiol level"
Reference:
- British Menopause Society (BMS) (July 2025). BMS Tool for Clinicians Measurement of serum estradiol in the menopause transition.