ABSTRACT
Estradiol is the most potent form of mammalian estrogenic steroids and acts as the major female sex hormone. As such, estradiol plays an essential role in the regulation of the menstrual cycle, in the development of puberty and secondary female sex characteristics, as well as in ageing and several hormonally-mediated disease states. In some, oral administration of estradiol induced systemic allergic contact dermatitis, in another, it was tolerated well. A patient sensitized to testosterone had positive reactions to 2 patches containing estradiol. In vivo, testosterone is metabolized to estradiol by the enzyme complex aromatase, particularly in the liver and adipose tissue. Therefore, cross-reactivity does not come as a surprise.
