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E-book 70 Years of Levothyroxine

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Penilaian

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n the opening chapter of this book, we consider the history of the therapeutic use of levothyroxine (LT4). Recognition of the therapeutic value of LT4 emerged from experience gained from, essentially, empirical administration by physicians of crude thyroid extracts to people with advanced sequelae of hypothyroidism [1–4]. These clinical experiments arose from early studies of people we would today describe as having severe congenital hypothyroidism. Accordingly, our story begins in the atter half of the nineteenth century, when these pioneering observations were being made, continues to the current management of hypothyroidism with LT4 and con-cludes with a brief review of outstanding research issues in this fast-moving field. Fig. 1 provides a timeline of key events along this journey, and these important advances are described below. An appreciation of thyroid disease as a clinical entity began during the second half of the nineteenth century [1–4]. Briefly, sporadic, and widely spaced, reports in medical journals during this period described young, short-lived individuals pre-senting with growth retardation and “sporadic cretinism”, which were found to be associated with minimal or absent thyroid tissue [5–7]. Such cases today would be described as congenital hypothyroidism, with the term “sporadic” used to differ-entiate them from “endemic cretinism”, associated with goitre in iodine-deficient regions, which had been described centuries before. Later work during this period introduced the term, “myxoedema”, to describe the anatomic appearance of the thy-roid in these patients [1].Surgery to remove goitre was being performed at this time, for example, to relieve symptoms of compression in the neck, despite a continuing lack of understand-ing of the function of the thyroid gland [8]. One contemporary study showed that removal of the entire thyroid led to the development of symptoms resembling those of “sporadic cretinism”, and this observation led the author to restrict future surger-ies to partial resection of the thyroid, with better outcomes [9]. Elsewhere, thyroid-ectomy in animals was shown to produce symptoms reminiscent of myxoedema, providing further strength to the association of athyroid status with “sporadic cre-tinism” [10]. These extreme cases were the first demonstrations of the pathophysi-ological importance of the thyroid gland to healthy development although not based on any understanding of the function of the thyroid. Other experiments conducted at this time noted that thyroidectomy was lethal to dogs, but that the health of the animals could be preserved temporarily by grafting the thyroid elsewhere in the animals’ bodies [11]. Even so, it was assumed that the function of the thyroid was allied to detoxification of the blood, rather than to an independent and specific endo-crine function [3]. It had been suggested in about 1820 (soon after the characterisation of iodine as a chemical element) that the limited efficacy of dietary ingestion of foodstuffs such as sponges or seaweed in the diet (an ancient, traditional remedy for goitre) was con-nected to the presence of iodine in these items [12]. The first attempts at iodine supple-mentation, either using a tincture of iodine, or with iodised salt, followed during the following decade [4]. A correlation between scarcity of iodine in the environment and an increased prevalence of goitre was published some 30 years later [13]. This was followed by further trials of iodine supplementation in three Departments of France where problems with goitre were especially severe. These were largely successful, and it was reported in 1869 that about 80% of cases of goitre responded favourably to treatment [14]. Several problems with the conduct of these trials led to their early cessation; these included an excessively high dose of iodine (which commonly caused hyperthyroidism in adult recipients), continuing scepticism among the medical pro-fession, and reluctance to participate by citizens who feared that curing their sons’ goitres would remove an obstacle to their being conscripted for military service [4].

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Ketersediaan

Informasi Detail

Judul Seri

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No. Panggil

616.4 LIP s

Penerbit

Switzerland : Springer Nature., 2021

Deskripsi Fisik

141 hlm

Bahasa

English

ISBN/ISSN

9783030632779

Klasifikasi

616.4

Tipe Isi

text

Tipe Media

computer

Tipe Pembawa

online resource

Edisi

-

Subjek

Diseases of Endocrine Systems, Endocrinology

Info Detail Spesifik

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Pernyataan Tanggungjawab

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Versi lain/terkait

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