Tests of Thyroid Function

Thyroid Disease in Clinical Practice Thyroid Disease in Clinical Practice I. Ross McDougall MB, CHB, PhO, FACP, FRCP (Glas) Professor of Radiology and Medicine, Stanford University School of Medicine, California Springer-Science+Business Media, B.V. I~nl First edition 1992 © 1992 1. Ross McDougall Originally pub1ished by Chapman & Hall in 1992. Softcover reprint of the hardcover 1st edition 1992 Typeset in 10/12pt Palatino by Graphieraft Typesetters Ud., Hong Kong ISBN 978-0-19-520936-5 ISBN 978-1-4899-2881-8 (eBook) DOI 10.1007/978-1-4899-2881-8 Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the UK Copyright Designs and Patents Act, 1988, this publication may not be reproduced, stored, or transmitted, in any form or by any means, without the prior permission in writing of the publishers, or in the ca se of reprographie reproduction only in accordance with the terms of the licences issued by the Copyright Licensing Agency in the UK, or in accordance with the terms of licences issued by the appropriate Reproduction Rights Organization outside the UK. Enquiries concerning reproduction outside the terms stated here should be sent to the publishers at the London address printed on this page. The publisher makes no representation, express or implied, with regard to the accuracy of the information contained in this book and cannot accept any legal responsibility or liability for any errors or omissions that may be made. A catalogue record for this book is available from the British Library To Liz, Shona and Stewart Contents Preface xi 1 Thyroid structure, development and developmental abnormaIities 1 1.1 Gross structure 1 1.2 Microscopic structure 3 1.3 Development 4 1.4 Developmental abnormalities 6 Key facts 10 References 10 2 Thyroid physiology 12 2.1 Introduction 12 2.2 Regulation of thyroid function 12 2.3 Formation of thyroid hormones 16 2.4 Autoregulation of the thyroid 20 2.5 Transport of hormones in serum 21 2.6 Metabolism of thyroid hormones 23 2.7 Iodide cyde 24 2.8 Action of thyroid hormones 27 2.9 Calcitonin 28 Key facts 28 References 29 3 Tests of thyroid function 34 3.1 Introduction 34 3.2 Total thyroid hormones 35 3.3 Pituitary-thyroid axis: TSH (newand old technologies) 40 3.4 Hypothalamic-pituitary axis: (TRH test) 42 3.5 Dynamic and imaging studies of the thyroid 43 3.6 Tissue diagnosis 59 3.7 Miscellaneous tests 63 Key facts 66 References 67 4 CIinical examination 75 4.1 Introduction 75 4.2 General 75 4.3 Examination of the thyroid 75 4.4 Diagnostic indices 78 Key facts 81 References 81 viii Contents 5 Hyperthyroidism 82 5.1 Introduetion 82 5.2 Graves' disease or diffuse toxie goitre 83 5.3 Functioning autonomous thyroid nodule, single and multiple 118 5.4 Toxie multinodular goitre 125 5.5 Hyperthyroidism with low uptake of radioiodine 126 5.6 Iatrogenie hyperthyroidism 127 5.7 Faetitious thyrotoxieosis 127 5.8 Hamburger thyrotoxicosis 128 5.9 Silent thyroiditis 128 5.10 Postparturn thyroiditis 128 5.11 Subacute thyroiditis 129 5.12 Hyperthyroidism due to cancer invading thyroid 129 5.13 Iodine-induced hyperthyroidism Ood Basedow phenomenon) 129 5.14 Struma ovarii 132 5.15 Metastatic functioning thyroid cancer 132 5.16 Hyperthyroidism due to a high TSH or TSH-like material 133 5.17 Pituitary hyperthyroidism 134 5.18 Non-pituitary cancer secreting TSH 135 5.19 Hyperthyroidism with inappropriate TSH secretion 135 5.20 Hyperthyroidism from trophoblastic tumours 135 5.21 Hyperthyroidism in the young, the old and pregnant 136 5.22 Hyperthyroidism in children 136 5.23 Hyperthyroidism in the elderly 138 5.24 Hyperthyroidism in pregnancy and in the neonate 139 5.25 Thyroid crisis (storm) 142 Key facts 144 References 146 6 Hypothyroidism 163 6.1 Introduction 163 6.2 Aetiology 163 6.3 Prevalence 165 6.4 Clinieal features 166 6.5 Associated diseases 171 6.6 Diagnosis 171 6.7 Treatment 173 6.8 Thyroid replacement in patients with angina pectoris 176 6.9 Anaesthesia and surgery in hypothyroidism 177 6.10 Myxoedema coma 177 6.11 Hypothyroidism in children 179 6.12 Neonatal hypothyroidism 179 6.13 Cost benefit analysis of screening for hypothyroidism 181 6.14 Inborn errors of synthesis of thyroid hormones (dyshormonogenesis) 182 6.15 Scintigraphy in neonatal hypothyroidism 183 6.16 Treatment 183 6.17 Acquired (juvenile) hypothyroidism 184 Contents ix 6.18 Hypothyroidism in the elderly 184 Key facts 185 References 186 7 Management of thyroid nodules 193 7.1 Introduction 193 7.2 Causes of thyroid nodule 194 7.3 Clinical evaluation of patient and nodule 194 7.4 Testing thyroid function 195 7.5 Investigations 195 7.6 Management of cystic nodules 202 7.7 Role of thyroid suppression 203 7.8 Summary 204 Key facts 204 References 204 8 Thyroid cancer 207 8.1 Introduction 207 8.2 Classification of thyroid cancers 207 8.3 Differentiated thyroid cancer: papillary 208 8.4 Differentiated thyroid cancer: follicular 232 8.5 Differentiated thyroid cancer: Hurthle cell 234 8.6 Differentiated thyroid cancer: dear cell 236 8.7 Differentiated cancers in extrathyroidal sites 236 8.8 Undifferentiated cancer: anaplastic 237 8.9 Medullary cancer 240 8.10 Lymphoma of the thyroid 244 8.11 Metastases to the thyroid 246 Key facts 247 References 248 9 Thyroiditis 257 9.1 Introduction 257 9.2 Hashimoto's thyroiditis 257 9.3 Subacute thyroiditis (granulomatous or de Quervain's thyroiditis) 263 9.4 Silent thyroiditis including postpartum thyroiditis 268 9.5 Acute (suppurative) thyroiditis and thyroid abscess 271 9.6 Riedel's thyroiditis (invasive fibrous thyroiditis) 273 9.7 Radiation thyroiditis 274 Key facts 275 References 276 10 Simple goitre <non-endemic, non-toxie goitre) and multinodular goitre 282 10.1 Introduction 282 10.2 Aetiology and pathogenesis 282 x Contents 10.3 Pathology 283 10.4 Clinieal presentation 284 10.5 Diagnosis and investigations 284 10.6 Treatment 285 10.7 Substernal goitre 285 Key facts 289 References 289 11 Iodine deficiency disorders, endemie goitre and endemie cretinism 291 11.1 Introduction 291 11.2 Aetiology 291 11.3 Clinieal presentation 292 11.4 Prophylaxis and treatment of endemie goitre and cretinism 292 11.5 Problems of iodization programmes 293 11.6 WHO classification for endemie goitre 293 11.7 Endemie cretinism 294 Key facts 295 References 295 12 Changes in thyroid function tests in physieal and psychiatrie diseases 297 12.1 Introduction 297 12.2 Organie non-thyroidal illness 297 12.3 Psychiatrie illness 300 Key facts 301 References 302 13 Radiation and the thyroid 304 13.1 In trod uction 304 13.2 Radiation physics 304 13.3 Dosimetry 311 13.4 Thyroid disease due to external radiation 313 13.5 Thyroid disease due to internal radiation 318 Key facts 321 References 321 Index 325 Preface Thyroid diseases are common. They indude physieal and mental can distort thyroid func hyper- and hypothyroidism, enlargement of tion tests so that thyroid dysfunction is dia the gland both diffuse and nodular, solitary gnosed inappropriately. This is addressed in nodules both benign and malignant, in Chapter 12 with adviee that should de flammatory diseases, rare congenital defects crease this occurrence. Because radiation in structure and inborn errors in function. to the thyroid can cause dinieally relevant Many are simple to diagnose and treat, thyroid disease and because some of the others are not. The literature often com diagnostic tests and treatments involve plicates rather than simplifies issues. My in administration of radioactive iodine to the tention is to use personal experience, the patient, Chapter 13 brings together some teaching of others and distillation of the aspects of radiation biology in relation the literature as the basis for a text which will the thyroid. allow the physician to deal with specific, The author has been lucky to be associated patient-related problems. The first four with academic and practising physicians and chapters are general. There are short chap basic scientists whose main interest was 'the ters on the structure and function of the thyroid'. Early in my training I had the great thyroid followed by a review of tests. The fortune of working in Professor Edward fourth chapter is an outline of dinical eva McGirr' s department at Glasgow Royal In luation, but this is no way substitutes for firmary. There I worked most dosely with personal experience at the bedside or in the the late Bill Greig on the interface of thyroid dinie. and nuclear medicine. Subsequently, I had a The chapters on hyper- and hypothyroid fellowship to work with the late Joe Kriss at ism should help define the specific cause Stanford University Medical Center where and management of patients with these we were colleagues for 15 years. In both of problems. Evaluation and treatment of thyr these institutes I worked with, and learned oid nodules and thyroid cancer cause con from, many fine clinicians and scientists. siderable differences of opinion. These However, I have to pay a special tribute to differences are reviewed and specific re Joe Kriss, who embodied all the characteris commendations are outlined. Thyroiditides, ties patients ho pe for in their physieian with although not related causally, symptomati the creative mind of a researcher and the cally or therapeutically, are placed in Chap ability to transmit his thoughts with preci ter 9 for convenience. Simple enlargement of sion and darity. the thyroid (Chapter 10) and iodine deficien It is possible the book may be of value to cy dis orders (Chapter 11) receive less cover medical students and physicians in training, age than their dinical importance worldwide but it is aimed primarily at practising physi merits, but the key issues are covered.

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