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

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Although such an occurrence is extremely rare, it does underline the importance of persistence and of getting a proper diagnosis.

Why Does the Thyroid Become Underactive?

There are two main types of hypothyroidism: primary, when the thyroid is the source of problems; and secondary, when a fault in the hypothalamus or pituitary has a knock-on effect on the thyroid.

• Primary hypothyroidism can be brought on by:

• thyroiditis (inflammation of the thyroid), a feature of Hashimoto’s thyroiditis (see page 49) and postpartum thyroiditis (PPT)

• surgical or medical treatment for an overactive thyroid (see Chapter 5) or surgery and/or radiotherapy for certain kinds of cancer

• prescription medications and over-the-counter drugs containing iodine (iodides), such as lithium for treating manic-depression, and some cough remedies

• congenital (inborn) problems affecting the thyroid, such as absence or abnormal development of the thyroid or errors of metabolism (see Chapter 9).

• Secondary hypothyroidism is caused by failure of the hypothalamic – pituitary – thyroid hormonal axis leading to deficient secretion of hormones by the hypothalamus or pituitary, caused by:

• known damage to the hypothalamus or pituitary as a result of previous surgery, meningitis, trauma or radiation to the brain

• the development of tumours or cysts.

Variable Symptoms

Although many of the symptoms of an underactive thyroid are common to both primary and secondary hypothyroidism, there are some suggestive differences that either you or your doctor may notice.

Table 3.3Clues to help you determine whether you have primary or secondary hypothyroidism

Is Your Thyroid Underactive?

Symptoms of hypothyroidism are not always easy to detect. Table 3.4 lists some symptoms that you may experience, that others may notice or that your doctor may detect.

Table 3.4 Symptoms suggestive of hypothyroidism

Life in the Fast Lane: Hyperthyroidism

Overproduction of thyroid hormones – hyperthyroidism – is caused by an overactive thyroid. The state of being hyperthyroid, called thyrotoxicosis, is sometimes easier to spot than hypothyroidism, partly because there may be rather dramatic mental and physical effects. However, symptoms are not always obvious, but may just creep up on you. It may only be when someone else comments on how you have changed or when your doctor notices some signs that the condition is diagnosed.

Whereas an underactive thyroid slows your body down, an overactive one speeds it up, causing your metabolism to race uncontrollably. As Jan, who has Graves’ disease, the most common cause of hyperthyroidism, describes it:

I’d had a lot of trouble in my marriage and a lot of stress generally after I left. The first thing I noticed was that I was full of energy. I couldn’t sit still, I had to be working, working out, cooking or doing something with the kids all the time. I started to drink to try and slow myself down. As time went on, I couldn’t sit down long enough to think and I became totally exhausted. My muscles started to waste away, even though I was exercising so much. My periods stopped. I had bouts of breathlessness, which were diagnosed as asthma. I couldn’t think straight, my mind was so overactive. I felt as if my head was full of twittering sparrows and I had what I can only describe as an ‘electrical buzzing’ in my head.

As Jan’s account illustrates, when the thyroid becomes overactive, the body burns energy at a tremendous rate. If you are affected, you can eat like an elephant without putting on weight; in fact, more often than not, you will lose pounds instead.

As the gland continues to step up production, you may feel constantly hot and sweaty, and find yourself stripping off and throwing windows open, even on cold days. You may also notice a change in bowel habits – needing to go more often and sometimes having diarrhoea, a symptom so common that it’s not unusual for hyperthyroidism to be first diagnosed at a gastroenterology clinic. Some of those affected experience a raging thirst and pass large amounts of urine, similar to that seen in people with undiagnosed diabetes.

Anyone who has been around someone with an overactive thyroid can’t fail to notice their boundless ‘get up and go’. Sufferers pace like caged lions, talking 19 to the dozen, yet are unable to muster any concentration. Their energy never flags for a second, even at bedtime. Recalls Louise, 38:

I couldn’t settle for the jumble of racing thoughts that were flying around my brain. My sex drive increased, too – I wouldn’t leave my husband alone.

Louise’s experience echoes that of many others, and is thought to occur because of the increased turnover of male-type sex hormones – androgens – which control the libido and are converted into the female hormone – oestrogen – in the body.

Mood Swings

Wildly swinging moods are a key feature of thyroid overactivity. One minute you are optimistic and on top of the world, the next you are plunged into the depths of despair. Nervousness and anxiety are also characteristic, probably as a result of increased sensitivity to the effects of the stress hormone adrenaline, which triggers the body’s ‘fight or flight’ reaction. Unfortunately, some find that when they report symptoms to their doctor, they are seen to be a cause rather than an effect of their problem. Just as people with an underactive thyroid may find themselves dismissed or treated with antidepressants, it has been known for those with hyperthyroidism to be referred for psychiatric help for manic-depression.

Appearance Matters Too

An overactive thyroid can affect your physical appearance. Your skin becomes thin, pink and moist; you tend to flush easily, and your palms may become red and sweaty. Your hair becomes fine and flyaway, and falls out while your nails become thin and flaky.

A number of those with Graves’ disease develop thyroid eye disease (see Chapter 8) and some will also develop an infiltrating skin disorder causing the skin on the front of the shins to become lumpy, red and thickened skin in the front of the shins – a condition also known as pretibial myxoedema. These symptoms can appear years before or after the thyroid becomes overactive.

Some people with hyperthyroidism develop thyrotoxic tremor – a constant, fine trembling that is most noticeable when the hands are stretched out. This is thought to be due to an oversensitivity to adrenaline. Maria, 35, a freelance photographer, recalls that this tremor was the first thing she noticed when her thyroid became overactive:

I first became aware of the problem when I noticed that I wasn’t able to hold my camera steady. I couldn’t hold a pen straight to write either, and I started having palpitations. My heart beat so fast that, on one occasion, I was convinced that I was going to have a heart attack. I was losing weight rapidly: I went from my usual eight-and-a-half to nine stone to seven-and-a-half stone, even though I was eating like a pig. And I was irritable and bad-tempered.

Bone, Heart and Other Muscles

Like hypothyroidism, untreated hyperthyroidism can damage the heart. The palpitations Maria describes are a common feature, caused by an overactivity of the heart muscle that causes the pulse to accelerate; this can lead to palpitations and an irregular heartbeat, called atrial fibrillation (see Chapter 10), especially in older women. Breathlessness is another common symptom and this, too, is sometimes misdiagnosed as asthma or bronchitis. The slightest exertion can bring on an attack.

An overactive thyroid can also disturb your body’s calcium balance, accelerating the natural rate of bone loss. Bone is a living tissue that is constantly being built up and broken down. Thyroid overactivity speeds up the breakdown part of this natural cycle. This, in turn, can lead to thinning of the bones (osteopenia) and an increased risk of osteoporosis when you are older.

Weakness as a result of wasting of the muscles is another problem for about half of all hyperthyroid sufferers. As Sarah remembers:

I am a marathon runner, but I just couldn’t run at all. If I got down on the floor, someone had to help me up.

Very rarely – and particularly in those who are Asian – people with an overactive thyroid can experience periodic paralysis, attacks of profound muscle weakness or paralysis brought on by eating sugary or starchy foods. This is due to a disturbance of the body’s ability to maintain a constant concentration of potassium in the blood.

Menstrual Problems and Pregnancy

Hyperthyroidism, too, can be responsible for menstrual problems, including PMS. Although not as likely to affect fertility as an underactive thyroid, it is nevertheless associated with a number of complications during pregnancy (see Chapter 9).

The Goitre Connection

As with an underactive thyroid, an overactive one can also cause a goitre (see page 56). If the doctor listens through a stethoscope, it may be possible to hear the blood surging turbulently through the vessels in the goitre, a noise known as ‘thyroid bruit’ (a bruit is the sound made in the heart, arteries or veins when the blood flows at an abnormal speed).

Is Your Thyroid Overactive?

The symptoms of hyperthyroidism can often sneak up insidiously. Table 3.5 lists some of the clues that you or others may notice, or that your doctor may detect.

Why Does the Thyroid Become Overactive?

Hyperthyroidism may also be primary, when something goes wrong with the thyroid itself, or secondary, when the fault lies with the hypothalamus or pituitary.

Primary hyperthyroidism can be due to:

• Graves’ disease, caused by autoimmunity (see page 50)

• Thyroiditis (inflammation of the thyroid), caused by autoimmunity (see page 52)

• Nodular thyroid disease, for example, toxic multinodular goitre (Plummer’s disease), characterized by the development of multiple lumps, or a ‘hot’ nodule (toxic adenoma), where a single lump becomes overactive (see page 57)

• Postpartum thyroiditis, wherein problems develop after giving birth (see Chapter 9)

• Excess iodine either from the diet (from food or, in some instances, herbal supplements) or from medications (such as the drug lithium, used to treat manic-depression; amiodarone, a drug used to treat irregular heart beat; and interferon, used to treat certain types of cancer)

Table 3.5 Symptoms suggestive of hyperthyroidism

• Overdosage of thyroxin treatment for hypothyroidism. On rare occasions, hyperthyroidism can be a consequence of people with an underactive thyroid accidentally or intentionally taking too much medication, a condition known as thyrotoxicosis factitia.

Secondary hyperthyroidism can be brought on by:

• Faulty pituitary function, on rare occasions due to a pituitary tumour, leading to an abnormal production of thyroid-stimulating hormone (TSH), thereby causing the thyroid to produce too much hormone

• Cancer-related problems. In extremely rare instances, hyperthyroidism may be the result of a thyroid cancer that has spread.

Autoimmune Thyroid Problems

Hashimoto’s Thyroiditis

In adults, the most common reason for the thyroid to become underactive is autoimmunity. Hashimoto’s thyroiditis (Hashimoto’s disease) – named after Hakuru Hashimoto, the Japanese doctor who originally described it in 1912 – is the most common type of autoimmune hypothyroidism. The other type is called ‘spontaneous atrophic hypothyroidism’, where the thyroid wastes away and shrinks. This is more likely to affect older women.

THE SYMPTOMS

At first, although you may not feel ill. You may develop a small, painless goitre and, as time goes on, this may become tender and feel uncomfortable when you swallow. Curiously, when the disease first develops, you may develop symptoms of an overactive thyroid (see page 48). This is only temporary, however. As the disease progresses, the thyroid becomes increasingly less active, and the typical signs and symptoms of hypothyroidism eventually set in.

Graves’ disease

For six to eight out of 10 women, hyperthyroidism is a result of Graves’ disease, another autoimmune condition that is the mirror image of Hashimoto’s disease. It is most common between the ages of 20 and 40, but it can be seen in girls as young as five and, very occasionally, in the infants of sufferers.

Robert James Graves, a charismatic Irish physician, gave his name to the illness. In 1835, he wrote a paper outlining all the symptoms now recognized as Graves’ disease in the UK and USA. In Europe, the same condition is often called ‘von Basedow’s disease’, after Dr Carl A. von Basedow, a private practitioner in Germany, who described the illness in 1840. Graves was the first to make the connection with pregnancy – the women he wrote about were all pregnant (see Chapter 9).

Confusing Symptoms

Graves’ disease may be associated with all the classic symptoms of hyperthyroidism but, according to the UK-based endocrinologist Dr Anthony Weetman, these can be extremely variable. Writing in the New England Journal of Medicine, Weetman explains that both age and duration of thyroid overactivity play a part in determining which symptoms predominate. In over half those affected, nervousness, fatigue, rapid heart beat, heat intolerance and weight loss are key symptoms. However, in the over-50s, weight loss and loss of appetite are more common. Atrial fibrilliation is rare among the under-50s, but affects up to a fifth of those over 50. And while 90 per cent of younger women have a firm, diffuse goitre, only 75 per cent of the over-50s do. Glucose intolerance (inability to metabolize glucose) and, more rarely, diabetes can accompany Graves’ disease, and if you have diabetes, the condition will increase your need for insulin.

Is It Really Graves’ Disease?

Graves’ disease has been called the ‘great masquerader’ because it doesn’t always produce the typical symptoms of an overactive thyroid. Confusingly, the condition can take a relapsing-remitting form in which the thyroid swings from overactivity to normal to underactivity and back to overactivity again. Even more curiously, 5 per cent of those with Graves’ disease become hypothyroid over time, sometimes becoming lethargic and passive, and unable to do anything but lie in bed all day. Patricia, 34, who was diagnosed with an overactive thyroid two years ago, recalls:

In the past, I was always a very active person. I love sports and would be out playing tennis or squash or doing aerobics four or five times a week. A couple of years ago, I began to feel completely worn out. I started to put on weight. My muscles ached all over and I felt fluey. I really struggled to get through each day. I was backwards and forwards to the doctor for about six months but, each time, I was diagnosed as having flu or a virus.

My mother suffers from an underactive thyroid so when my neck began to swell, I asked the doctor if I could have a thyroid problem. He said no. He thought it was a problem with my ears, because my job involves a lot of flying abroad. Eventually, I saw an ENT specialist, who felt my neck and said, ‘Are you being treated for your thyroid problem?’ Two days later, I was back at the hospital having tests, which showed I had an overactive thyroid. My symptoms weren’t at all typical, which I guess is why it took so long to get a diagnosis.

Such symptoms tend to be more common in older women who develop an overactive thyroid and who may be labelled depressive or thought to be suffering from a hidden cancer. This type of hyperthyroidism – known as apathetic thyrotoxicosis – can be particularly tricky to detect, which can lead to delays in diagnosis. But a diagnosis is important as this kind of apathy is a sign that the body’s metabolism has reached the point of burnout and in need of urgent treatment to bring the thyroid under control.

Thyroiditis

Thyroiditis is inflammation of the thyroid. There are three different types:

• Viral or subacute thyroiditis is the result of a virus infecting the thyroid, although no single virus has yet been identified as the culprit. It tends to be especially common between the ages of 20 and 50. The condition usually resolves within two to five months, although one or two out of 10 of those who get it will have a recurrence. Symptoms may include:

• swelling, pain and tenderness of the thyroid

• flu-like symptoms and/or a raised temperature

• symptoms of thyroid overactivity (see page 43) lasting for two to four weeks, sometimes followed by symptoms of hypothyroidism.

• Autoimmune thyroiditis is yet another autoimmune effect on the thyroid. Mild autoimmune thyroiditis can affect as many as one in five women who are otherwise healthy, often without their even being aware of it. In a small number – about one in 10 – the disease may progress to overt hypothyroidism. The condition tends to run in families, so if you have a family history of this condition (see page 129), the doctor may suggest testing for thyroid antibodies.

• Postpartum thyroiditis (see Chapter 9).

Triggers and Causes

Hashimoto’s thyroiditis, Graves’ disease and most kinds of thyroiditis are autoimmune conditions. What triggers the immune system to see the thyroid as its enemy in such cases? All have a genetic component, yet studies of identical twins show a relatively low genetic effect; clearly, environmental and lifestyle factors must play key roles. Research has been mainly aimed at Graves’ disease, but there is reason to believe that similar mechanisms may be involved in other autoimmune types of thyroid disease.

Could Infection Play a Part?

Because the immune system is commonly triggered by infection, the hunt has been on for some time to identify a possible specific infection that might trigger autoimmune thyroid problems. One of the most intriguing suggestions, described by US surgeon Mr David V. Feliciano in the American Journal of Surgery in November 1992, was that Graves’ disease might be sparked off by a food-poisoning bug known as Yersinia enterocolitica, a distant relative of the plague bacteria.

Although Y. enterocolitica has not proved to be as significant as Feliciano suspected, a study published in the journal Clinical Microbiology and Infection in 2001 reported that patients with Hashimoto’s thyroiditis also had a 14-fold increase in Y. enterocolitica antibodies – so the question is still open.

Is Stress to Blame?

Over the past few years, there has been increasing evidence that, in a number of illnesses, the immune system is weakened by negative mental states such as fear, tension, overwork, anxiety and exhaustion – in a word, stress. So, could stress be responsible for autoimmune thyroid problems? The answer seems to be yes, especially in the case of Graves’ disease.

Doctors in the 19th century observed that Graves’ disease often followed a period of severe emotional stress – a frightening episode or ‘actual or threatened separation from an individual upon whom the patient is emotionally dependent’. One 19th-century doctor, Bath-based physician Caleb Hillier Parry, described the onset of symptoms in the patient ‘Elisabeth S, aged 21’:

[She] was thrown out of a wheelchair in coming fast down hill, 28th April last, and very much frightened, though not much hurt. From this time she has been subject to palpitation of the heart, and various nervous affections. About a fortnight after this period she began to observe a swelling of the thyroid gland.

Today, Dr Mark Vanderpump, secretary of the doctors’ organization the British Thyroid Association, observes:

When compared with people without thyroid disease or patients with toxic nodular goitres, patients with Grave’s more often give a history of psychological stress before the onset of hyperthyroidism through immune suppression followed by immunological hyperactivity. The same phenomenon is seen post pregnancy as well when the immune system is suppressed during pregnancy and relapse follows delivery.

In Norway and Denmark, the incidence of hyperthyroidism increased during the first years of the Second World War. In their book Thyroid Disease: The Facts, Drs R.I.S. Bayliss and W.M.G. Tunbridge mention research showing a significant rise in the incidence of Graves’ disease in Northern Ireland since the start of political troubles in 1968. More recently, researchers reported a dramatic fivefold increase of Graves’ disease in eastern Serbia during the war in the former Yugoslavia.

Significance of Life Events

Back in 1991, a team of Swedish researchers found that those developing Graves’ had often suffered an unhappy event in the recent past. The death of a close relative or friend was reported by 15 per cent of Graves’ patients compared with 10 per cent of a control group. The disease was also more likely to strike those who were divorced or less happy with their jobs – suggesting that long-term anxiety, unhappiness and other negative feelings could be a factor.

In 1998, Japanese researchers reported in the journal Psychosomatic Medicine that women diagnosed with Graves’ disease were seven-and-a-half times more likely to have experienced stressful life events although, curiously, the same finding did not hold true for men. In 2001, another study, reported in the journal Clinical Endocrinology, found a five-and-a-half-fold increase in ‘life events’ in individuals with Graves’ compared with those with toxic nodular goitre and those without thyroid problems. Intriguingly, in this study, people with Graves’ had also experienced more happy – but still potentially stressful – events like a promotion, a pay rise, getting engaged or married, or having a baby.

None of these studies prove conclusively that stress is to blame for triggering Graves’ disease, but they do suggest a significant connection. However, fewer connections have been found linking stress with Hashimoto’s thyroiditis. Clearly, more research is needed to unravel the precise mechanism by which stress may tip the thyroid into overactivity and to determine whether it is a factor in thyroid underactivity.

Smoking

Smoking has long been a known risk factor for the thyroid eye disease Graves’ ophthalmology (see Chapter 8). However, its role in Graves’ disease has been less clear. Nevertheless, the evidence is beginning to stack up. In the 1998 Japanese study mentioned above, smoking was found to be an independent risk factor for women developing Graves’. This finding was echoed in a Danish study, published in the journal Thyroid in January 2002, in which 45 per cent of women diagnosed with Graves’ disease were current or former smokers, compared with 28 per cent of those with toxic nodular goitre and 23 per cent of those with autoimmune hypothyroidism.