Thyroid for Dummies (14 page)

10_031727 ch05.qxp 9/6/06 10:46 PM Page 63

Chapter 5: Dealing with an Underactive Thyroid

63

Getting the right amount

The amount of thyroid hormone that you receive is determined using a TSH

test (assuming that central hypothyroidism is not the diagnosis). Depending on the particular laboratory doing the test, the TSH level is usually 0.3–4.5

µU/ml (microunits per millilitre). (Check out Chapter 4 for more on this test.) Keep in mind that some doctors question whether this measure actually is the normal range for TSH. Ten per cent of the population tests positive for thyroid autoantibodies and probably has autoimmune thyroid disease. Most of these people are not given the diagnosis of hypothyroidism. When a laboratory creates a normal range, it tests several hundred or more people who are considered free of thyroid disease, usually because they have no signs or symptoms. The laboratory measures their TSH and states that ‘this is the range for TSH in the normal population.’ Are they really measuring a normal population when one of every 10 people tested may have an undiagnosed thyroid disease?

Some patients do not feel normal with a TSH between the normal range, and feel better when given enough thyroid hormone to lower their TSH to below the usual range.

If you are receiving treatment for hypothyroidism and don’t feel right on your current dose of replacement thyroid hormone, ask your doctor to check your TSH. Then ask the doctor whether they are willing to prescribe more thyroid hormone to lower your TSH further. Some endocrinologists believe that complete wellbeing is only restored when T4 levels are towards the upper limit of normal, and the TSH level is slightly suppressed below the normal range.

This dosage is something you need to discuss with your doctor so you can aim for a result that minimises risks of side effects while at the same time optimising your metabolic rate so problems such as weight gain are less problematic.

Tinkering with thyroxine doses yourself is never a good idea. Excess thyroxine is potentially toxic and can cause rapid pulse, palpitations, heart rhythm abnormalities such as atrial fibrillation and even angina, not to mention diarrhoea, tremor, headache, sweating, muscle weakness, and insomnia.

Another important point is that hypothyroidism is not necessarily permanent.

Up to 25 per cent of people with autoimmune hypothyroidism may return to normal thyroid function at a later date. The reason is that production of the autoantibodies that block the action of TSH may decline over time.

If your autoimmune hypothyroidism has gone on for several years, ask your doctor if you can stop the thyroid hormone replacement for four to six weeks to see whether or not your TSH remains low. (Do not stop taking your hormone replacement without your doctor’s supervision.)

10_031727 ch05.qxp 9/6/06 10:46 PM Page 64

64
Part II: Treating Thyroid Problems

On the other hand, a thyroid gland that is failing due to autoimmune thyroiditis goes through several levels of failure. At first, you may need little thyroid hormone to replace what you’re missing. With time, more of your thyroid tissue may fail or the antibodies that block TSH may increase, and you will need more. Seeing your doctor on a regular basis to check for this increasing (or decreasing) failure of the thyroid is important.

After your thyroid function stabilises, see your doctor every six months or every year to have your TSH level checked and your dosage of thyroid hormone altered if necessary. These checkups are important because you may not feel different in yourself, even if your thyroid function gradually declines.

Testing hormone levels

It takes about four weeks for a change in your dose of replacement thyroid hormone to make a difference in your lab tests. If your dose is changed, you’re normally retested regularly to ensure that you’re on the correct dose.

11_031727 ch06.qxp 9/6/06 10:43 PM Page 65

Chapter 6

Taming an Overactive Thyroid

In This Chapter

ᮣ Recognising the symptoms of hyperthyroidism

ᮣ Linking hyperthyroidism and Graves’ disease

ᮣ Deciding on treatment

ᮣ Battling severe hyperthyroidism

Hyperthyroidism refers to the excessive production of thyroid hormones. The condition leads to many signs and symptoms that suggest your body is, in effect, speeding up.

Hyperthyroidism is fairly common. Each year, about 1 new case is diagnosed per 1,000 people, most of whom are women. That number adds up to more than 60,000 new cases in the United Kingdom every year, because the United Kingdom’s population is at least 60 million.

Most people with hyperthyroidism (about 80 per cent) have an autoimmune disorder called Graves’ disease, which this chapter discusses in detail. As well as causing signs and symptoms of hyperthyroidism, Graves’ disease also affects the eyes and skin. These abnormalities are all bound together by the fact that they result from autoimmunity. (Refer to Chapter 4 for a discussion of ‘Thyroid autoantibodies’.) In some circumstances, a person has hyperthyroidism but no eye or skin disease, and blood tests show no evidence of autoimmunity. These people do not have an autoimmune disorder, but their hyperthyroid state produces the same medical picture as if they had Graves’

disease.

This chapter shows you how to recognise hyperthyroidism, tells you about the treatment options and the possible complications that may occur as a result of the treatment or the disease itself. Many people believe that if you have hyperthyroidism, you’re lucky because the condition makes weight control or weight loss easier. This chapter shows you why that thinking is seriously flawed.

11_031727 ch06.qxp 9/6/06 10:43 PM Page 66

66
Part II: Treating Thyroid Problems

Picturing Hyperthyroidism

Tammy is the mother of Stacy and Karen, who have recently learned that they have autoimmune thyroiditis and hypothyroidism, respectively (refer to Chapter 5). Tammy is a very active person, but lately she has noticed a lot of things wrong with her, and they are getting worse.

Tammy feels warm all the time, and her skin is moist. A few months ago, she lost some weight without trying and was delighted, but the weight loss has continued despite the fact that she has a really strong appetite and is eating more than usual. She often feels her heart racing, which makes her very nervous. She notices that her hands shake when she just sits quietly. She goes to the bathroom more frequently than usual, both to urinate and to open her bowels.

The changes in Tammy are not lost on her husband, Patrick, or her daughters.

They notice that she is constantly staring at them, though when they question her, she denies it. Patrick, in the course of giving her a massage to help her relax, notices a bump on the front of her neck that was not there before.

Tammy’s family insists that she see their family doctor.

The GP asks a number of questions and does a physical examination. He discovers that Tammy’s thyroid is enlarged, and he finds a skin abnormality on her lower legs. He tells the family that Tammy almost certainly has hyperthyroidism due to Graves’ disease. The final diagnosis requires only some confirmatory blood tests, and the outcome of those tests is so certain that the doctor prescribes Tammy medication to calm her heart rate down, as well as referring her to an endocrinologist at the local hospital for specialist advice.

The tests confirm the diagnosis. Tammy sees the specialist and immediately starts taking an antithyroid pill once a day. By the end of three weeks, she feels better, and after eight weeks, she is her old self. She is a bit disappointed when the pounds start coming back on, but she feels so good that she returns to her health club and sheds several of them in no time. Patrick is, of course, delighted to have his wife back at moderate instead of high speed. Now he wants to visit a London theatre in the West End as he knows she would not sit through a play in her previous condition.

Listing the Signs and Symptoms

of Hyperthyroidism

Hyperthyroidism, whether caused by Graves’ disease or another condition, produces consistent signs and symptoms that affect every part of your body.

11_031727 ch06.qxp 9/6/06 10:43 PM Page 67

Chapter 6: Taming an Overactive Thyroid

67

The major abnormalities are described in the following sections, grouped according to the organ system of the body that is affected.

The body generally

Hyperthyroidism can raise your body temperature persistently high. You may lose weight despite an increased appetite. The weight loss is due to the loss of lean body tissue like muscle, not due to a loss of fat. In rare cases, however, you may gain weight because you’re eating so many calories. Hyperthyroidism can cause you to feel weak. You may feel enlarged lymph glands all over your body (for example in your neck, armpits, and groin), because Graves’ disease is an autoimmune disease and the lymph system is a key player in autoimmunity. Your tonsils, which are part of the lymph system, are also enlarged.

Other possible reasons for enlargement of the lymph glands can be more serious than Graves’ disease, so if you experience this symptom, see your doctor.

The thyroid

When Graves’ disease is the cause of hyperthyroidism, your thyroid is enlarged in a symmetrical way and the entire gland is firm. When a single overactive nodule (a lump on your thyroid) is to blame for hyperthyroidism, that nodule is large, but it often causes the rest of the gland to shrink. (Head to Chapter 7 for a discussion on nodules.) When a multinodular goitre is responsible (see Chapter 9), you can feel many lumps and bumps on your thyroid.

If you put your hand over an enlarged thyroid, you can often feel a buzzing sensation, called a thrill, which results from the great increase in blood flow through the overactive gland. You can also hear the thrill with a stethoscope; the sound is called a bruit (pronounced
brooeee
).

The skin and hair

Hyperthyroidism can make your hands feel warm and moist, and they may appear red. You may experience a loss of skin pigmentation (a condition called vitiligo) in places, which is another sign of autoimmunity. Other areas of your skin may appear darker. Sometimes hair changes, too, becoming fine, straight, and unable to hold a curl.

11_031727 ch06.qxp 9/6/06 10:43 PM Page 68

68
Part II: Treating Thyroid Problems

The heart

Hyperthyroidism can cause a rapid pulse, which you feel as heart palpitations. The first sign of Graves’ disease is sometimes
atrial fibrillation
, an irregular heart rhythm. If the person is older and already has heart disease, hyperthyroidism can induce heart failure. The condition can also bring on heart pain (angina) or make pre-existing angina worse because your heart is working hard, beating too rapidly. You may also experience shortness of breath.

The nervous system and muscles

If you have hyperthyroidism, your fingers have a fine tremor when you hold your hands out. The loss of muscle tissue leads to weakness. Your reflexes are increased and some people find it impossible to sit still. The mental changes associated with hyperthyroidism are discussed in Chapter 2.

Basically, if you’re hyperthyroid, most likely you’re anxious, nervy, you don’t sleep as much as you used to, and you have rapidly changing emotions, from exhilaration to depression.

The reproductive system

Hyperthyroidism can cause a decrease in fertility because it interferes with ovulation in women. Menstrual flow is decreased as well and may even stop temporarily until treatment brings your thyroid function back towards normal.

The stomach and intestines

If you are hyperthyroid, food moves more quickly through your intestines than it used to, and you have more frequent bowel movements or even diarrhoea. You may experience nausea and vomiting.

The urinary system

As blood flows more quickly through your body, more blood passes through your kidneys that are filtering out more urine than normal. As a result, you need to visit the bathroom more frequently. In turn, you feel more thirsty than usual.

11_031727 ch06.qxp 9/6/06 10:43 PM Page 69

Chapter 6: Taming an Overactive Thyroid

69

The eyes

Any form of hyperthyroidism results in changes to the eyes, most of which are reversible. Your upper eyelids may look pulled up higher so that you can see more of the white above each pupil; this feature makes you appear as if you’re staring and pop-eyed. When you are asked to look down, your upper eyelid may not follow your eye, which exposes even more of the white. This disorder is called lid lag.

Graves’ disease can also cause more serious eye problems, which are not reversible. These problems are discussed later in this chapter.

Confirming a Diagnosis

of Hyperthyroidism

The signs and symptoms described in the previous section usually lead to a conclusive diagnosis of hyperthyroidism, which is confirmed by blood tests.

Among the lab findings that can lead to a diagnosis, the following are most important:

ߜ The levels of both free T4 and free T3 (thyroid hormones) in your blood are elevated, and the thyroid-stimulating hormone (TSH) level is suppressed (refer to Chapter 4). The definitive tests for hyperthyroidism are the TSH and the free T4. In 1 per cent of people with hyperthyroidism, a raised level of free T3 can occur, with a normal level of free T4; this condition is called T3 thyrotoxicosis (see the section

‘Recognising Other Causes of Hyperthyroidism’ later in this chapter).

ߜ If Graves’ disease is the cause of hyperthyroidism, the levels of peroxidase autoantibody and antithyroglobulin autoantibody are elevated (check out Chapter 4).

ߜ Your blood glucose (sugar) level is elevated because your body is absorbing food so rapidly.

ߜ You may have insulin resistance, and diabetes may develop or become worse if it’s already present. (Diabetes improves after the hyperthyroidism is treated.)

ߜ Blood tests of your liver function (such as the alkaline phosphatase and bilirubin levels in the blood) are sometimes elevated.