Bio-identical hormones


Bioidentical hormone replacement therapy (BHRT) is different from traditional hormone replacement therapy (HRT) in that the hormones are identical chemically to those our bodies produce naturally and are made from plant estrogens  extracted from yams and soy. The hormones used in traditional HRT are made from the urine of pregnant horses and other synthetic hormones. There are two types of BHRT - compounded (cBHRT) and regular (rBHRT). There is no evidence to support the practice of cBHRT although pharmacies in UK do compound these. These are not prescribable on the NHS. 

Body identical HRT has the same chemical structure as the hormones in your body. That means that when you take it, you're literally topping up your own hormones. Body identical HRT is regulated medication that can be prescribed on the NHS and privately.

For estrogen: almost all forms of HRT prescribed in the UK are now body identical estrogen. Look out for the term estradiol (often made from the yam plant).

For progesterone: the only body identical progesterone is a tablet called Utrogestan. It's an oral treatment, though it can also be taken vaginally. Look out for the term micronised progesterone. The other way to get body identical progesterone is through the mirena coil, which slowly releases micronised progesterone into the cervix and surrounding area. If you have the mirena coil you do not usually need additional progesterone.

What are the brands of body identical HRT?

  • Evorel
  • Sandrena gel
  • Oestrogel
  • Estradot patches
  • Elleste Solo patches

Proven advantages for rBHRT over conventional HRT


Progestogens may not be alike with regard to potential adverse metabolic effects or associated breast cancer risk when combined with long-term estrogen therapy. Micronised progesterone and some progestogens have specific beneficial effects that could justify their use besides their expected actions on the endometrium. Synthetic analogues of progesterone (progestins/progestogens ) bind to the glucocorticoid, mineralocorticoid and androgen receptors. This can lead to unwanted side effects such as fluid retention, acne and weight gain. Progestogens and progesterone can lower mood through stimulation of the neurotransmitter gamma amino butyric acid; whilst progesterone has sedative effects through its intermediate metabolites, progestogens can cause PMS-type side effects including anxiety and irritability.

Venous thromboembolism (VTE)

It is well recognised that unlike oral estrogen, transdermal estrogen does not appear to increase the risk of VTE. Observational and case control data suggest that the use of certain progestogens e.g. dydrogesterone and micronised progesterone (D/MP) may reduce the increased risk of VTE conferred by oral estrogen, compared to that noted with other synthetic progestogens.

Cardiovascular risks

D/MP have a neutral effect on lipid and glucose metabolism and on vascular tone. The beneficial effects of estrogen are therefore not attenuated as they are with some synthetic progestogens such as medroxyprogesterone acetate which can blunt the increase in HDL cholesterol, increase insulin resistance and reduce arterial compliance. Smaller studies such as KEEPS and ELITE using MP have demonstrated superior outcomes to WHI.

Breast cancer

D/MP have pro-apoptotic or neutral effects on breast epithelial cell proliferation – this is in contradistinction to the effects of androgenic progestogens such as medroxyprogesterone acetate which have a proliferative effect. Data from the E3N Cohort observational study showed that estrogen with D/MP is associated with a significantly lower relative risk) than for other types of combined HRT. These differences require confirmation from further studies.

Endometrial protection

Endometrial protection and avoidance of breakthrough bleeding may not be as consistent with separately administered oral MP as it is with standard oral continuous combined regimens. However, this may be partly due to lack of compliance due to the requirement for MP to be used separately with estrogen. Vaginal administration may improve endometrial protection through uterine first pass effect.

Key messages

  • cBHRT products are not recommended by the BMS they are not evidence based for effectiveness and safety and because rBHRT options are available
  • There is insufficient evidence to justify multiple serum and saliva hormone tests often claimed to precisely individualise cBHRT
  • Claims for the benefits of cBHRT have been largely extrapolated from studies of conventional rBHRT
  • rBHRT studies have demonstrated some advantages over other types of HRT, particularly those with androgenic progestogens
  • Further data from larger studies on major cardiovascular and breast endpoints are required to confirm the potential benefits of rBHRT
  • The management of women with menopause related problems should be underpinned by the principles and guidelines of the British Menopause Society and wherever possible, regulated products should be prescribed.
  • Bio-identical hormones are not prescribable on the NHS. Body-identical or conventional HRT is prescribable on the NHS.


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