The Healthy Thyroid: What you can do to prevent and alleviate thyroid imbalance. Patsy Westcott

is much controversy surrounding the issue of mild thyroid disease – or should it be called early or pre-thyroid disease? Despite being more widely recognized, there is little consensus on its significance and whether or how it should be treated. No one truly knows how important it is as a cause of ill health or how often it might lead to full-blown thyroid disease. Other questions remain, too: Should it be tested for in the absence of symptoms? Should women with symptoms suggestive of thyroid problems, such as tiredness and depression, be treated even if blood tests are apparently normal? Should widespread thyroid screening be introduced and, if so, at what age and how often should testing be performed?

      Just as in 1995, there is a lot of debate, but no definitive answers.

      Why Me?

      Almost every woman included in this book wanted to know why she, in particular, had developed a thyroid disease. Unfortunately, there are no simple answers to this question. Despite its prevalence, the experts themselves still do not fully understand what causes the thyroid to misbehave. As with so many illnesses, one of the most pressing questions is whether nature or nurture lies at the root of the problem.

      The cracking of the human genome, the inherited ‘database’ of some 40,000 to 50,000 genes containing all of the instructions for life, has led to an explosion of genetic research – and some interesting insights into the origin of certain kinds of thyroid problems. Some of the genes involved in certain kinds of thyroid cancer have been identified as well as other possible ‘candidate’ genes that may lead to an increased risk of developing an autoimmune thyroid disease.

      However, although genes undoubtedly play a role, they are not the whole story. As with any illness with a genetic component, possessing one or more of these predisposing genes may give you a tendency to develop a particular problem – in this case, thyroid disease – but it is your environment and individual lifestyle that may yet determine whether you actually will.

      The Immune Connection

      The role played by the immune system in triggering a number of thyroid disorders remains a controversial topic. Autoimmune thyroid disease, which underlies both hypo- and hyperthyroidism, is caused by failure of a fundamental mechanism: the body’s ability to recognize its own organs and tissues as belonging to itself.

      If the body fails to recognize itself, it produces self-attacking proteins – known as autoantibodies – to destroy its own tissue. Experts are becoming increasingly aware of a number of diverse thyroid problems due to the production of such autoantibodies, including:

      

      • Hashimoto’s thyroiditis, which causes an underactive thyroid

      • Graves’ disease, which causes an overactive thyroid

      • Myxoedema, or generalized swelling of the skin and other tissue

      • Subclinical hypo-/hyperthyroidism, mild or hidden thyroid under-/overactivity

      • Thyroiditis, or inflammation of the thyroid

      • Postpartum thyroiditis, or inflammation of the thyroid after childbirth

      • Thyroid eye disease (TED).

      Putting the Clues Together

      Women, as we already know, are much more likely than men to develop thyroid disease. Many of those interviewed for this book added, almost as an afterthought, ‘My mother (or sister, or daughter) has thyroid problems, too.’ In particular, Graves’ disease and Hashimoto’s thyroiditis seem to cluster in families. In the past, this was dismissed as a coincidence. Recently, however, the new science of molecular genetics has led a number of researchers to look for an underlying inheritance factor in the development of autoimmunity. It is now generally agreed that as much as 10–15 per cent of us inherit an immune system with the potential to turn against itself.

      Nevertheless, the development of thyroid problems is not just a matter of inheriting a faulty set of genes. Many people possess autoantibodies and do not go on to develop full-blown thyroid disease. In fact, it is estimated that only about one in 10 of those with an inherited tendency to develop thyroid antibodies will actually have thyroid problems.

      One of the main aims of research, therefore, is to discover the possible triggers of thyroid problems. We know that the immune system can be damaged by many aspects of the 21st-century lifestyle that seem to have potential roles in the development of thyroid disease. Pollution, ageing, diet, stress, viral and bacterial infections, and habits like smoking and drinking are just some of the factors being explored by scientists in the hopes of finding out why the thyroid becomes faulty. Since 1995, much more information has been accrued on the roles these factors may play in triggering thyroid disease – and one important risk factor could simply lie in being female.

      The Hormone Connection

      The thyroid gland is involved in virtually every bodily process, including those of the reproductive system, and thyroid disease is linked to a number of specifically female problems (see Table 3.1).

       Table 3.1 Links between thyroid disorders and the reproductive system

      The first clue that something may be wrong with the thyroid gland is often when a woman consults the doctor on a ‘woman’s problem’, such as menstrual irregularities, difficulty in getting pregnant, miscarriage, postnatal depression or menopausal symptoms. It is also increasingly recognized that thyroid problems may be confused with or aggravate the symptoms of women’s problems such as PMS and the menopause.

      With so many women’s problems being linked to thyroid disease and, conversely, so many thyroid problems being associated with the reproductive cycle, could it be that the female hormones play a part in susceptibility to thyroid disease? The answer is most likely yes. Research suggests that the two main female sex hormones, oestrogen and progesterone, moderate the activity of the immune system – hence the preponderance of thyroid disease in women.

      The involvement of hormones and the immune system could also explain why the thyroid may misbehave for the first time during pregnancy and after birth. It also provides a reason for why so many women develop debilitating postpartum thyroiditis (PPT), which is often confused with postnatal depression.

      One of the most striking developments since the first edition of this book has been the increasing awareness that the brain and nervous system, the immune system and endocrine (hormonal) system, all previously thought to be completely separate systems, do not work in isolation. This has led to the development of new fields of study such as psychoneuroendocrinology and psychoneuroimmunology, which are dedicated to exploring the body-mind connection and the way in which each ‘talks’ to the other.

      With Women in Mind

      This book is an exploration of these and other issues. Chapter 2 looks in detail at the thyroid gland and how it works to enable readers to understand the links between the thyroid and other body systems, and why – when it goes wrong – there may be such wide-ranging effects. The chapter also outlines some of the latest thinking on the immune system and the part it plays in thyroid problems.

      Chapter 3 examines all the things that can go wrong with your thyroid, and explores some of the latest theories for how thyroid problems arise in an attempt to answer that nagging question, ‘Why me?’ There is also more detailed information on thyroid nodules (lumps) and thyroid cancer. Despite being one of the simplest forms of cancer to treat, survival rates in the UK have, until now, lagged woefully behind those of other countries.

      Chapter 4 tackles the problem of getting a proper diagnosis. It includes a description of the various tests that may be performed, and explores the issue of what is normal and the difficulties involved in interpreting thyroid function tests.

      Chapter