Hormone confusion OPINION Dr Martin Hill, GP, anti-ageing medicine specialist 13 July 2007 BIO-IDENTICAL hormone replacement has received significant media interest and has been the subject of medical debate. Central to the controversy of hormone replacement is the form of hormone prescribed and the mode of delivery of that hormone. The medical literature reports that not all oestrogens are the same and that progestins are different from progesterone, therefore the benefit/risk profiles of each combination will be different.1-5 A major contributing factor in the controversy has been confusion in terminology. Bio-identical hormones are compounds that have the same structure as their endogenous counterpart. They are iso¬molecular with the human hormone and have the same physiological response. They are derived by necessity from plant-based steroidal substrates and are formed by chemical synthesis in laboratory processes. These compounds are therefore synthetic. The term ‘natural’ is misleading and requires qualification, as it may have different meanings among scientists, consumers and manufacturers. The only true ‘natural’ hormones are conjugated equine oestrogens (CEE) and desiccated thyroid extract, both of which are purified non-synthetic products derived from animal sources. Bio-identical hormones are available commer¬cially and non-commercially and are prescribed by most doctors. Many bio-identical hormones are TGA approved and have PBS listing. Examples of such are oestradiol in oral, patch, implant, nasal spray and cream form; oestriol cream and pessaries; testosterone in patch, implant and gel form; L-thyroxine and triiodothyronine; human growth hormone; and hydrocortisone (oral and topical). Some forms of bio-identical hormones are not commercially available in Australia and can only be obtained by prescription from a compounding chemist. Examples of these are oral micronised progesterone, DHEA and transdermal testosterone for women. The former has been commercially available in Europe and North America since 1980; the latter has been the subject of research and development by doctors associated with Monash University. Bio-identical hormones may therefore be prescribed from PBS and non-PBS sources; the latter by necessity complements the former. Non-PBS and individualised hormone combinations may be sourced from a compounding chemist. The use of a compounding chemist allows more flexibility to the prescriber. For example, there is choice in composition of gel and cream for transdermal delivery, slow released or non-slow released oral preparations, and of hormone combinations. Compounding has particular importance in hormone replacement, as each person has a unique physiology due to mutations in genes that code for enzymes involved with metabolic pathways and receptors. The optimal treatment of hormone-related conditions involves the precise adjustment of hormone dose, combinations and route of delivery according to clinical and biochemical response. PBS medications may not provide sufficient dose and dose combination to meet individual patient needs. As hormones have an effect on most physiological processes, their deficiencies are associated with age-related conditions. The prescription of medication from a compounding chemist allows personalised prescription according to choice of cream or gel base, dose, and combinations of hormones in various routes of delivery that may not be commercially available. REFERENCES 1. Verheul HA, Coelingh-Bennink HJ, Kenemans P, Atsma WJ, Burger CW, Eden JA, Hammar M, Marsden J, Purdie DW. Effects of estrogens and hormone replacement therapy on breast cancer risk and on efficacy of breast cancer therapies. Maturitas 2000;36(1):1-17. 2. Coelingh-Bennink HJ. Are all estrogens the same? Maturitas 2004;47(4):269-75. 3. Minkin MJ. Considerations in the choice of oral vs. transdermal hormone therapy: a review. J Reprod Med 2004;49(4):311-20. 4. Kuhl H. Pharmacology of estrogens and progestogens: influence of different routes of administration. Climacteric 2005;8 Suppl 1:3-63. 5. Wiegratz I, Kuhl H. Progestogen therapies: differences in clinical effects? Trends Endocrinol Metab 2004;15(6):277-85.