Admeda Arzneimittel: Thyroid Gland

The Thyroid Gland

Thyroid hyperfunction (Hyperthyroidism)
- Treatment of Hyperthyroidism

General Information

The situation in Europe has shown that approximately 10% of the population has an enlarged thyroid gland (goiter). With age, this rate increases to even 40-50%. Of these 40-50%, a number could have been helped if they had received treatment early enough. Many of the operations that are performed year for year could have been avoided. The rate of hyperthyroidism incidence in Europe amounts to several hun-dred thousand per year.

Structure and Function of the Thyroid

The word thyroid stems from the Greek word thureos and means oblong shield. As the name implies, the thyroid is situated like a shield before the trachea. It is butterfly-shaped and weighs up to 19 grams in women and up to 25 grams in men.

The thyroid gives off its secretion inwardly, into body tissue and from there into the bloodstream. These secretions are called hormones. Thyroid hormones are indis-pensable. A critical component of hormones is iodine, which is taken up via water and food. From iodine and protein building blocks, the thyroid produces triiodothyron-ine and thyroxine, or T3 and T4 for short. These hormones are released into the body as needed.

Hormones stimulate development and growth, step up metabolic processes and en-ergy conversion and are of great significance to mental development and the devel-opment of the central nervous system. In short: a loss of function slows down physical and mental life processes, and an increase in function speeds them up.

Iodine Deficiency

The population in Europe consumes just 1/3 of the recommended dosage of iodine. The recommendation calls for 150-300 micrograms. In times of hormonal transition such as puberty, pregnancy or menopause, the required amount is even higher. Therefore, in part due to their monthly menstrual cycles, women are affected 3 times more often than men.

It is easy to increase iodine intake
You should only use iodised salt in your household. As industrially prepared food-stuffs are not usually seasoned with iodine table salt, domestic intake is not enough to provide the body’s daily allowance. Moreover, high sodium intake entails the risk of high blood pressure and associated circulatory disorders.

The most important source for increasing iodine intake is saltwater fish (ocean perch, pollock, mackerel, cod); i.e. not freshwater fish such as trout for example. The con-sumption of one portion of saltwater fish twice a week means saying goodbye to worries of iodine deficiency. As far as possible, you should make sure that the fish you eat is fresh or frozen, as processed fish products contain hardly any iodine. Frying destroys less iodine than cooking.

Classification of the degree of severity of iodine deficiency on the basis of io-dine excretion in urine (WHO)

grade I	excretion of 50-150 g iodine/g creatinine
grade II	excretion of 25-50 g iodine/g creatinine
grade III	excretion below 25 g iodine/g creatinine

An iodine deficiency of grade I or grade II is prevalent in Europe.

Iodine Deficiency Goiter (Goiter)

Iodine deficiency goiter occurs, as the name already indicates, from a lack of iodine. If not enough iodine is available, no thyroid hormone can be produced. As a result, the level of this hormone in the blood drops. This deficiency is then reported back to the brain with the message that the thyroid needs to actively produce more hormones for the metabolism. To confront this situation, the thyroid grows in order to be able to exploit the last bit of iodine left in the body. Thus, in the event of too little iodine, too much tissue is the result. That means that when faced with the presence of a sus-tained state of iodine deficiency, the thyroid attempts to compensate for this condition by growing.

Categorisation of goiter size on the basis of palpitation findings according to the recommendation of the WHO

grade I	palpable goiter
grade Ia	not visible when bending head back
grade Ib	visible when bending head back
grade II	visible goiter when neck is in a normal position
grade III	very large goiter, visible even from a distance

How long a goiter grows will depend on the degree of iodine shortage and to what extent iodine deficiency forces the thyroid to grow. However, the body defines individually when a state of iodine deficiency is reached and when not. The ability of cells to absorb iodine differs from person to person. A goiter can be present for many years before any dysfunction occurs. Left untreated, a goiter almost always leads to hyperthyroidism.

Thyroid hyperfunction (Hyperthyroidism)

If too many thyroid hormones are produced in the thyroid, the body can become flooded with thyroid hormones, signalling the onset of the condition : thyroid hyperfunction (Hyperthyroidism).

These symptoms may occur due to hyperthyroidism:

weight loss

increase in appetite

increase in heart rate

nervousness, restlessness

frequent bowel movements

heat intolerance, moist skin

hair loss

fatigue

muscle weakness

menstrual disorders

Circulatory system:
Rapid, at times irregular pulse, slightly elevated blood pressure.

Skin:
The skin is warm and velvety. Patients sweat a lot and prefer colder rooms. Afflicted persons tend to dress lightly. Nails break easily and increased hair loss is noted during brushing. The hair is silky soft and “doesn’t lay right”.

Gastrointestinal system:
Tendency to diarrhoea or frequent bowel movements. Stool that was once firm becomes soft.

Musculature and skeletal system:
Moderate grade osteoporosis is possible, muscular weakness, muscle aches and tension.

Blood:
Slight anaemia

Hormonal system and metabolism:
Menstrual disorders, decrease in libido and potency. In the event of insufficient treatment during pregnancy, there is a risk of miscarriage, premature birth or birth defects.

Nervous system:
Patients become nervous. They have difficulty controlling their emotions. Restless, unmotivated movements and sleeping disorders are common. The irritability can build up leading to serious psychotic states.

Goiter:
Often there is presence of thyroid enlargement, or a goiter forms simultaneously with onset of the hyperfunction. However, there may be a lack of visible gland enlargement.

Eyes:
With Graves’ disease, watery eyes, foreign body eye sensation, photosensitivity, redness and protrusion of the eyes may occur.

Hyperthyroidism can be the manifestation of thyroid segments which have liberated themselves and separated from tissue, thus becoming autonomous. However, it can also be caused by Graves’ disease. On the whole, these two diseases account for 95% of all hyperthyroidism cases.

Causes of Hyperthyroidism

immunethyreopathy (Graves’ disease)

autonomy

inflammation

secondary hyperthyroidism

hormone production outside the thyroid: e.g. carcinomatous metastases

hyperthyroidism caused by external influences: e.g. caused by medicaments

Autonomy
The term autonomy refers to the independency of certain functions from regulative influences. In the thyroid, cells defy regulation and uninhibitedly produce hormones. These cells become “nodules” which overheat due to overactive production. Autonomy can occur as single nodules (unifocal autonomy or autonomous adenoma), in the form of multiple nodules (multifocal autonomy) or as scattered cell heaps (disseminated autonomy). Although autonomy does tend to develop more prevalently in older goiters, it can still be found in normalsized thyroids. Hence, even people without goiters are not safe from thyroid hyperfunction caused by autonomy.

Graves’ Disease
If autonomy is not the cause of the overactive thyroid, then the signs point to the presence of Graves’ disease. Graves’ disease is a socalled autoimmune disease: Thereby various defence proteins (antibodies) of the body’s own police force (immune system) are formed to attack the cells of the thyroid. This means that the im-mune system, which usually protects against disease entering the body from the out-side, itself becomes a link in the chain of destructive events. The thyroid “thinks” that the antibodies are thyroid-stimulating hormones (TSH) and begins to produce hor-mones. This leads to a hyperfunction. In 60 % of all cases, patients with Graves’ disease have greatly protruding eyeballs. Through the lymphatic system, these defence proteins infiltrate into the depths of the eye orbits. Here as well, autoimmune processes take place. In rare cases, a third area can become affected: the main front sections of the lower legs. Scientists still do not know why the body’s own immune system suddenly attacks itself. The cause of the disease is probably genetic on the one hand, but mental and hormonal processes seem to also play a role on the other hand.

The most common symptoms in Graves’ disease are of a mental nature.

Treatment of Hyperthyroidism

Medical Therapy
As an autoimmune disorder, Graves’ disease tends to heal itself. In order to bridge the time until the degeneration of disease processes, medical therapy is expedient. Therefore, thyreostatic long-term therapy is the treatment of choice for Graves’ disease. The duration of its existence is of key significance to the selection of the optimal form of therapy. Patients with “fresh” onset of hyperthyroidism will be treated with medicine as a general rule. If there are still indications after 1-2 years of the persistence of hyperthyroidism, then a surgical therapy form should be considered. Antithyroid drugs are thyroid inhibitors which curtail hormone production by preventing the thyroid from absorbing iodine.

Autonomy does not regress under the influence of antithyroid drugs. In this respect, as a rule, the thyreostatic therapy serves as a preparation to a definitive therapy in this case (operation or radioiodine).

Thyroid inhibitors curtail the production of hormones, but have no influence on those hormones that have already been produced and are “in storage”. Therefore, delayed effects are to be expected. For a while, from one up to three weeks time, the unset-tling symptoms will persist. At times, tranquillisers are also prescribed along with thyroid medicines. The initial dosage is adjusted according to the patient and the active ingredient in the thyroid inhibitor. If symptoms normalise after approximately 4 weeks, dosage will be reduced to a minimal so that the thyroid is not completely incapacitated.

Pregnancy and Breastfeeding
Maternal hyperthyroidism during pregnancy can be associated with an increased rate of miscarriage and birth defect. During the 10th – 14th week of pregnancy, foetal hormone production commences. Thence, the dosage of antithyroid medicine must be kept as low as possible. In the last trimester of pregnancy, hyperthyroidism often improves spontaneously.

During lactation, iodine therapy is only good for iodine deficiency goiter. However, thyroid inhibitors are passed into the breastmilk. Therefore, the antithyroid drug propylthiouracil is the treatment of choice, as its concentration in milk amounts to a maximum of one-tenth of the maternal blood serum concentration.

Nevertheless, gynaecologists, thyroid specialists and paediatricians should work together in this matter.

Effects of Therapy
If the treatment of hyperthyroidism was successful, hormone production slows down, the metabolism normalises and the body can put on weight again. At times, the patient will put on more weight than before, as the patient’s eating habits are still tailored to the increased metabolic state.

It should also be kept in mind that once muscle weakness is present, time is needed for the body to get back to its original strength. Therefore, immediate bounciness is not to be expected.

Peace and Quiet
An overactive thyroid can be countered with peace and quite. Sleeping and going for quiet walks has a positive effect on patients. A great deal of understanding is required from family members, as on the outside patients appear to be normal. However, on the inside a storm is still raging. Moreover, patients should avoid sunbathing and sports. Naturally, smoking is one of the things that should be avoided.

Avoidance of Iodine
Iodine-containing foods are taboo in the event of hyperthyroidism. Seafood should not be a part of the patient’s diet. However, if nutrition-based iodine deficiency was the cause of the disease, this will certainly not be a problem.

Radioiodine Therapy
For over 50 years, millions have undergone radioiodine therapy across the globe by now. Radioactive iodine is absorbed preferentially by hormone cells whose metabolic rate has increased. In the case of Graves’ disease, all cells are affected and diseased sections are reached in the event of autonomy. This way, inopportune thyroid tissue is deactivated cleanly, thoroughly and without complication, thus eliminating hyperthyroidism. Irradiation takes place on site and is limited to this site. An individual dosage can be determined which is oriented to the motto “as little as possible, as much as necessary.” The surrounding tissue is not exposed, therefore receiving no damage. For purposes of irradiation protection, therapy is conducted on an inpatient basis. Therapy takes a little bit longer because radioiodine treatment is very thorough. Effects begin to unfold after 4 weeks time. After this point, care should be taken to rule out hypothyroidism.

Operation
Today, thyroid operations rank number 3 on the most frequently performed operation list, following appendicitis and hernia operations. Surgery is performed on larger goiters, which, for example, block the windpipe, or in the event of nodular changes. Some nodules no longer absorb iodine, making radioiodine therapy ineffective. Surgery is only performed after the metabolism has been stabilised through drug treatment. This is the fastest way for the patient to rid himself of hyperthyroidism. Thyroid removal or removal of all but a small remainder of the thyroid can cause hypofunction, which would have to be treated with thyroid hormone tablets. However, the following holds true: it is better to have a healthy individual with an underactive thyroid than a mentally disturbed person with hyperfunction.

Thyroid Hypofunction (Hypothyroidism)

As opposed to hyperfunction, with thyroid hypofunction, the body has too little thyroid hormone available to it. Causes of this are congenital, stimulated by inflammation or extreme Iodine deficiency situations.

Thyroid hypofunction (hypothyroidism) develops gradually. As all body cells are de-pendent on thyroid hormones, effects of the shortage thereof spread out throughout the entire body. More than 2/3 of patients complain of less efficiency, weakness, lethargy, fatigue, chills, constipation and loss of memory. The overall scaled-down metabolism coupled with physical inactivity at the same level of food intake leads to patients becoming overweight. Further physical findings are manifested as oedema. Excess water causes swelling of the eyelids. The fingers become fat. The skin becomes dry and pale and even patchy at times.

Treatment of Hypothyroidism

As hypothyroidism is the effect of a lack of hormones, therapy consists of administering thyroid hormones such as thyroxine (T4). The synthetic made hormone is identi-cal to the body’s own so that no side effects can be expected if the proper dosage is given.