First Edition Introduction

Reproductive Endocrinology is the medical discipline related to hormones, neurotransmitters, paracrine and autocrine chemicals involved with the control of sexual development, sexual behaviour and reproduction. It is a fascinating subject to study and practise. Furthermore, it has improved our understanding of many basic gynaecological problems, which we used to take for granted without knowing their molecular or biochemical background. During my medical school years and PhD studies, an endocrine gland was defined as a ductless organ which produced hormones. These were in turn defined as chemicals carried by the blood, to cause their effects at distant sites. These concepts proved to be incorrect over the years. Hormones are not necessarily produced by ductless glands, and they could cause their effects both locally and at distant targets. The functional perception has also changed. Hormones and neurotransmitters are now considered as chemical communication means between different parts of the body. The local effects of hormones could be paracrine which denotes intercellular communication between neighbouring cells, and autocrine which denotes intracellular communication within the same cell. A new concept which is known as intracrine relates to the effects of unsecreted substances which bind to other intracellular substances within the same cell.

Providing contraceptive advice and hormone replacement therapy, induction of ovulation, management of the premenstrual syndrome, insulin resistance, hyperandrogenisation and premature ovarian failure are few examples of our daily routine within a gynaecology clinic. They all have a strong reproductive endocrinology background. Even without derangement in reproductive hormones production, increased oestrogen receptors activity coupled with genetic predisposition may have some bearing on the development of endometriosis. Similarly, increased skin androgen receptors and enzymatic activities have been reported as local causes of idiopathic hirsutism. With this broader application, it is evident that many gynaecological problems are in one way or another affected by dysfunctional hormones, their receptors or other related chemicals.

Accordingly, knowledge of the basic concepts of neuroendocrinology, and the interrelationship between the different endocrine glands especially the ovaries, adrenals and thyroid gland will improve our medical practice, when dealing with gynaecological problems with endocrine background. As gynaecologists, we need to understand how the hypothalamo-pituitary-ovarian axis interacts with the corresponding hypothalamo-pituitary-adrenal and thyroid axes, and how the later two interact with each other. The effects of the extremes of body weight on gynaecological practice are related mainly to their endocrine effects, though the initial causes may be psychological. The effects of different endocrine and non endocrine medications on endocrine glands, and the neuroendocrine control of reproduction should be appreciated. This is especially so for oestrogens, progestogens and androgens. We should understand the effects of oestrogens on the function of the thyroid and adrenal glands. This is especially so if either or both glands are dysfunctional. Furthermore, not all oestrogens are alike, not all progestogens are alike, and not all androgens are alike. Subgroups within these steroids share similar basic characteristics, but have different subsidiary effects, which are very important within the gynaecological practice. Knowledge of such information for instance may stop the common practice of repeated prescriptions of the androgenic norethisterone, which is 17a ethinyl 19 nortestosterone, to women with abnormal uterine bleeding and hyperandrogenic tendency. A non-androgenic progestogen can be equally effective. Similarly, appreciating the mode of action of clomiphene citrate as an oestrogen receptor modulator used to stimulate endogenous FSH production may stop the practice of prescribing it to women who already got high FSH levels because of ovarian ageing. On the other hand, understanding the differences between ovulatory and anovulatory dysfunctional uterine bleeding will stop the practice of prescribing progestogens to patients with the ovulatory type, which is useless and may even be harmful. These are only few examples of how better understanding of reproductive endocrinology can improve our gynaecological practice.

Hormones are produced in pulses, in a circadian rhythm, and with physiological variations during the menstrual cycle. This should be taken into consideration when requesting hormone investigations. Furthermore, inter-cycle variations are also common, and occasionally reported spurious results may not agree with the general clinical picture. This later problem may follow wrong timing of blood samples, use of undeclared medication by the patients, and the presence of heterotypic antibodies, just as examples. Such information should be taken into consideration during investigations of gynaecological problems, and the management plan should not be changed on the merits of such results.

This book has been written to introduce reproductive endocrinology with young gynaecologists in mind, and as a reference book for the more seasoned ones. A practical clinical approach has been adopted for presenting the information without using any mind twisters, and the chapters are arranged in a logical sequence. Repetition has been avoided by cross referring in-between chapters, when possible. A short summary has been included at the end of each chapter to focus the attention of the reader. Furthermore, a list of relevant references has also been included after each chapter, for those who developed special interest in any particular subject, and would like to have further information. To make it more affordable to the targeted reader, it was agreed that it should be printed in black and white and display the colour pictures on the black cover. I hope it will be a useful addition to the medical library.

Ahmed Abdel-Gadir