The Marion Gluck Clinic


The safety and science of bio-identical hormones

In 2002, a study by the World Health Initiative was the first to question the safety of conventional HRT, which had been prescribed to millions of women, globally, for many years.  Conventional HRT (Hormone Replacement Therapy) uses drugs that have been created to act like the hormones in your body – hence Hormone Substitution Therapy is a more accurate term.  The drugs used in the study were progestin (Provera) and conjugated equine estrogen (Premarin).  Premarin is made up of oestrogens which are taken from PREgnant MARes urINe, hence its name.  The study found an increased risk of many diseases; full details can be found here  Hormone substitute drugs are also used in the contraceptive pill and Mirena coil.  It is concerning to note that the health risks were not picked up during the clinical trials and quality studies required to license these medicines.

Bio-identical hormones are chemically identical to those hormones already in your body.  Taking these hormones is adding like-for-like, which is why fewer side effects are experienced.  Bio-identical hormones surged in popularity after the World Health Initiative published its findings, as women sought an alternative to conventional HRT.  Bio-identical hormones are used for many purposes, not only treating menopausal symptoms.  For example, they are also used to: reduce the risk of premature labour in pregnant women; treat postnatal depression (PND); resolve pre-menstrual syndrome (PMS); and rebalance thyroid levels.  Bio-identical progesterone is the only hormone recommended world-wide for use in fertility treatments.  By replacing the hormones that decline as you age, it is possible to feel healthier and more energised for longer.

There are licensed bio-identical estrogens (bio-identical estrogens are called estradiol and estriol), progesterone and testosterone products available.  At the Marion Gluck Clinic, we only prescribe bio-identical hormones and we specialise in prescribing compounded hormone products.  This allows us to personalise prescriptions for each patient and to minimise any possible side effects by prescribing exactly what your body needs.  Once we have assessed our patients’ hormonal requirements, we can combine multiple hormones into one medicine for convenience.

Compounding in the UK is a regulated activity, governed by either the MHRA or the General Pharmaceutical Council.  The Marion Gluck Clinic uses the Specialist Pharmacy to make its prescribed medications.  The Specialist Pharmacy buys high quality ingredients from suppliers that are compliant with Good Manufacturing Practice.  Its process of combining ingredients is governed by a computerised system that tracks every step and maintains this audit record of full traceability.  Quality assurance is taken seriously and a number of checks are performed on each medication.  Finally, products are issues with a patient information leaflet that explains how to take the medication and any potential side effects.  Pharmacists are always available to answer questions from patients and prescribers.

Some female cancers (e.g. breast, ovarian, endometrial) can be linked to estrogens and some male cancers (e.g. testicular) can be linked to testosterone.  These cancers can occur regardless of whether or not you supplement with additional hormones.  However, as hormones can act as growth factors, we are cautious in their use and carefully monitor all our patients.  This is why we ask our patients to undertake regular checks such as pelvic ultrasounds and mammograms for women and PSA tests for men.  We also monitor hormones levels using blood tests so that we can ensure levels are not higher than is physiologically appropriate and are correctly balanced.

There is plenty of peer-reviewed scientific research that demonstrates a safer risk profile for BHRT than conventional HRT.  Links to some of these studies are below.  However, we still need a longitudinal study on the safety of bio-identical hormones.

Ultimately, at the Marion Gluck Clinic we want every person to be empowered to choose their treatment, which is why it is our mission is to make bio-identical hormones accessible to everyone.  Too often, a patient is not informed of the risks of synthetic hormones and are presented with a binary choice: to take this medication or suffer in silence.

Bio-identical hormones and conventional HRT

The bioidentical hormone debate: are bioidentical hormones (estradiol, estriol, and progesterone) safer or more efficacious than commonly used synthetic versions in hormone replacement therapy?  Holtorf K.  Postgraduate Medicine. 2009 Jan, 121 (1): 73-85

Bioidentical hormones: what is all the hype about?  Panay N, Fenton A.  Climacteric. 2010; 13(1): 1-3.

What’s new in hormone replacement therapy: focus on transdermal estradiol and micronized progesterone.  Simon J.  Climacteric. 2012; Suppl 1:3-10.

A comprehensive review of the safety and efficacy of bioidentical hormones for the management of menopause and related health risks. Bioidentical hormones review.  Moskowitz D.  Alternative Medicine Review. 2006 Sep, 11 (3): 208-223

Hormones and breast cancer

Percutaneous estradiol/oral micronized progesterone has less-adverse effects and different gene regulations than oral conjugated equine estrogens/medroxyprogesterone acetate in the breasts of healthy women in vivo.  Murkes D, Lalitkumar PG, Leifland K, Lundstrom E, Soderqvist G.  Gynecological Endocrinology. 2012 Oct; 28(Suppl. 2): 12–5.

Could transdermal estradiol + progesterone be a safer postmenopausal HRT? A review.  L’Hermite M, Simoncini R, Fuller S, Genazzani AR.  Maturitas. 2008 Jul-Aug; 60(3-4): 185-201

Breast cancer risk in relation to different types of hormone replacement therapy in the E3N-EPIC cohort.  Fournier A, Berrino F, Riboli, Avenel V, Clavel-Chapelon F.  International Journal of Cancer 2005; 114(3): 448-454.

Unequal risks for breast cancer associated with different hormone replacement therapies: results from the E3N cohort study.  Fournier A, Berrino F, Clavel-Chapelon F.  Breast Cancer Research and Treatment. 2008 Jan; 107(1):103–11.

Use of different postmenopausal hormone therapies and risk of histology- and hormone receptor-defined invasive breast cancer.  Fournier A, Fabre A, Mesrine S, Boutron-Ruault MC, Berrino F, Clavel-Chapelon F.  J Clin Oncol. 2008; 26(8): 1260-8.

Risk of breast cancer by type of menopausal hormone therapy: a case-control study among post-menopausal women in France.  Cordina-Duverger E, Truong T, Anger A, et al.  PLoS ONE. 2013 Nov, 8(11):e78016

Hormones and cardiovascular disease

Lower risk of cardiovascular events in postmenopausal women taking oral estradiol compared with oral conjugated equine estrogens.  Smith NL, Blondon M, Wiggins KL et al.  JAMA Intern Med 2014; 174(1):25-34.

Estradiol-based postmenopausal hormone therapy and risk of cardiovascular and all-cause mortality.  Mikkola TS, Tuomikoski P, Lyytinen H, et al.  Menopause 2015; 22(9):976–83


The safety of 52 weeks of oral DHEA therapy for postmenopausal women.  Panjari M, Bell RJ, Jane F, et al.  Maturitas. 2009 Jul; 63(3): 240-245.

Update on the use of dehydroepiandrosterone supplementation among women with diminished ovarian function.  Barad D, Brill H, Gleicher N.  Journal of Assisted Reproduction and Genetics. 2007 Dec; 24(12): 629-634

Differential effects of oral versus transdermal estrogen replacement therapy on C-reactive protein in postmenopausal women.  Vongpatanasin W, Tuncel M, Wang Z et al.  Journal of the American College of Cardiology. 2003 Apr; 41(8): 1358-63.

Improvement of skin surface texture by topical estradiol treatment in climacteric women.  Masuda Y, Hirao T, Mizunuma H.  J Dermatol Treat 2013;24:312–17




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