Bio - Identical Hormones
Bio-identical hormones are popularly prescribed at perimenopause and menopause, particularly since the decline in use of standard hormone replacement therapy (HRT) following the Women's Health Initiative trial results of 2002. They include progesterone, DHEA, testosterone, and the oestrogens estradiol, estriol, and estrone. Synthesized in the laboratory from soy, or from the Mexican wild yam, they have the same molecular structure as hormones found in nature. They may be compounded in individually tailored doses and combinations and come as capsules, creams, patches, gels, lozenges, suppositories and under-the-tongue drops. Some standard forms of HRT are made from bio-identical hormones.
In New Zealand, bio-identical hormones can only be obtained on a doctor's prescription and are made under an exemption to the Medicines Act which allows a pharmacy to make a prescription medicine for a patient. These customized formulations are currently not approved and there are no guidelines for their use. In addition there are concerns regarding the purity, potency and quality of the compounded products.
There is no evidence to confirm that these products are safer than standard HRT or whether they carry the same risks for breast cancer, ovarian cancer, endometrial cancer, heart disease and stroke. Until reliable clinical evidence proves otherwise, it must be assumed that the risks are similar.
Taking oestrogen alone in any form is dangerous for women who have a uterus as it can lead to endometrial cancer. Oral progestagens in combined HRT offer protection against endometrial cancer, but it is unclear whether bio-identical progesterone is well enough absorbed to offer this protection. Studies to date are not reassuring.
The hormone testosterone taken with oestrogen is associated with an increased risk for invasive breast cancer.
It is normal to have lower levels of oestrogen and progesterone after menopause. Tests that identify low hormone levels are therefore not necessarily helpful. Research has found that saliva tests to measure progesterone hormone levels to not reliably show whether trans-dermal hormone creams are being absorbed into the body.
A small one-year placebo controlled study showed a reduction in hot flushes in women using progesterone every day. There are concerns that in this study some women started bleeding from the uterus. A more recent small 12 -week, double-blinded trial failed to find progesterone cream helpful for reducing menopausal symptoms.
A recent review of clinical evidence coupled with animal and in-vitro studies maintains that bio-identical hormone replacement therapy has greater health benefits for women at menopause than hormone replacement therapy with synthetic hormones.[i] The author claims that bio-identical hormones offer cardiovascular benefits and reduced risk of breast cancer. There has never been a large placebo controlled trial conducted on bio-identical hormones. The results of this meta-analysis may be understating harms just like the studies that were used to promote HRT until the WHI showed they were incorrect. Further studies are needed to determine the safety of bio-identical hormones.
[i] [i] Holtorf, K. The bio-identical hormone debate: Are bioidentical hormones (estradiol, estriol and progesterone) safer or more efficacious than commonly used synthetic versions in Hormone Replacement Therapy? Post-Graduate Medicine Vol 121, issue 1, January 2009.
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