Custom-compounded bioidentical hormone therapy: why so popular despite potential harm? The case against routine use

Wide rejection of conventional hormone therapy (HT) after the initial publication of the Women's Health Initiative (WHI) led to unjustified use of custom-compounded bioidentical hormones. In the USA, it became an unregulated drug manufacturer industry in disguise, without proper control and making false claims and misleading advertisements. Manufacturing quality is not ensured. Unspecific harm from compounding has occurred on a large scale, such as deaths from infected products and end-stage renal failure plus carcinoma due to confusion between different Chinese herbs. Oral estrogens increase venous thromboembolic and ischemic stroke events, even more when overdosed; these excess risks can be avoided by non-oral administration, readily accessible in custom-compounded HT by administering estradiol through diverse routes (of which transdermal is the best documented). Another risk specific to custom-compounded HT, resulting from estrogen/progestogen imbalance, might be excess endometrial carcinomas. HT can be optimized by continuously combining transdermal estradiol with progesterone (when required). Registered preparations do exist for such a more physiological treatment and therefore must be preferred. Custom compounding is only seldom legitimate, for example in case of allergy (such as to peanut oil) or to prescribe different combinations, doses or components (e.g. estriol, dehydroepiandrosterone or testosterone), even when not approved by local regulatory authorities despite being scientifically acceptable.