Introduction
The thyroid gland is an approximately 20-60 gram light organ that lies under the larynx and surrounds the esophagus and the vessels supplying the head. Despite its small size of only 3x2x11 cm on average, the thyroid gland has an important role in the body. The thyroid gland secretes the hormones T3 and T4, also known as triiodothyronine and thyroxine, through a complicated regulatory cycle.
These two hormones are essential for controlling metabolic processes in the human body. If the “thyroid gland values” are determined, this means the determination of these two hormones. The thyroid gland is a frequent trigger for various unspecific symptoms. The wide variety of symptoms shows how profound the effects of fluctuations in thyroid levels are.
Symptoms
The symptoms depend on the type of malfunction. If the thyroid gland values are too high, one speaks of hyperthyroidism, or hyperthyroidism. If the thyroid gland values are too low, it is called hypothyroidism.
Since the symptoms are very unspecific, other, more typical diseases are often clarified. However, thyroid dysfunction and changes in thyroid values are a very common clinical picture, the diagnosis of which has now become very simple, so that the disease is usually detected relatively quickly. Depending on which of the thyroid hormones is being considered, there are different reference ranges that limit the normal range.
It should be noted, however, that in certain groups of patients, such as pregnant women or children, there may be different normal ranges. This is especially true for the regulatory hormone TSH, which should be between 0.5 and 2.0 mU/L (milli units = thousandths of a unit per liter). In pregnant women, depending on the month, values between 0.1 and 3.0 can also be normal.
In children, too, higher values are sometimes considered normal. TSH is the most important and most significant marker of thyroid function. Unfortunately, some laboratories still work with outdated reference values.
In the course of the significant improvement in iodine supply over the last decades, an adjustment has been made for TSH. While in the past values up to 5 or 6 were accepted as normal, today these values should already be regarded as clearly excessive and thus as signs of a functional disorder. Unfortunately, not all doctors are up to date on this either.
It is therefore perfectly legitimate to discuss this topic with the treating physician. If the TSH exceeds or falls below the normal range, the thyroid hormones T3 (triiodothyronine) and T4 (tetraiodothyronine or thyroxine) are usually determined. These are usually determined as free (i.e. not bound to transport proteins) hormones.
The free T3 (fT3) should be between 2.6 and 5.1 pg/ml (trillionths of a gram per milliliter) and the fT4 between 10 and 18 ng/L (billionths of a gram per liter). It should be noted, however, that different units are used in some cases and that the figures for the normal range may therefore be different. Special values such as thyroid antibodies should not be detectable at all in the best case.
However, some healthy people also have them in their blood without this having a negative effect or requiring treatment. If too high thyroid gland values are detected, the first thing to do is to remain calm. The cause can be a variety of possible diseases, but in most cases there are good treatment options available.
An increase in the usual thyroid gland values is generally more likely to indicate a benign disease. First of all, it depends on which thyroid gland values are elevated. If the thyroid hormones T3 and T4 (thyroxine) are elevated, the thyroid gland is overactive.
The thyroid’s regulatory hormone, TSH, is then usually lowered. In the case of hypofunction, in most cases the reverse is the case, i.e. TSH is increased and T3 and T4 are decreased. The reason for this is that more TSH is produced so that the thyroid gland works more, but it cannot produce enough hormones.
Depending on the type of dysfunction, different diseases can be the cause. A hypofunction that occurs in adulthood is in most cases caused by the thyroid disease Hashimoto. It is treated by replacing the thyroid hormones in the form of tablets that are taken daily.
In case of hyperthyroidism, two diseases are common.One is the so-called thyroid gland autonomy, which can occur especially in older patients. This leads to an uncontrolled hormone production by part of the thyroid gland. As therapy, either the thyroid gland can be removed by surgery or a targeted radiation treatment from the inside by the so-called radioiodine therapy.
Elevated thyroid hormone levels can also indicate Graves’ disease. This disease can also occur in younger people. Typical signs are protruding eyes.
In addition, special thyroid gland values (antibodies) are usually elevated, which are additionally determined in suspected cases. If Graves’ disease is diagnosed, treatment with tablets that slow down the increased thyroid function (e.g. carbimazole) is usually carried out first. In many cases the disease is cured after a few months.
Otherwise, the already mentioned radioiodine therapy or surgery remain as therapy alternatives. Symptoms of hyperthyroidism are general: restlessness, nervousness, heavy sweating, increased body temperature, weight loss or a cachectic, i.e. emaciated, appearance. In addition, there are cardiac arrhythmia, high pulse, and possibly hair loss up to baldness.
Not all symptoms need to be present at the same time, usually not all of them occur. The Burch-Wartofsky Score is used to assess a possible thyrotoxic crisis. It is intended to provide information, independent of the actual thyroid gland values, as to whether there is a derailment of thyroid control.
Due to the complex interrelationships and the multitude of possible causes, the physician will advise the patient accordingly and, if necessary, order further examinations to determine the cause of the elevated thyroid gland values. The next step is to discuss a possible therapy and alternatives. Experts for thyroid diseases are, on the one hand, nuclear medicine specialists (radiologists) and, on the other hand, endocrinologists (doctors for hormone diseases).
However, the path should first lead to the family doctor, who will issue a referral if necessary. The first conspicuous value in a developing hypothyroidism is usually an elevated regulatory hormone (TSH). Even if there are no symptoms yet, an underfunction can be detected at an early stage.
The physician then also speaks of latent hypothyroidism. If the hypothyroidism is very pronounced, the thyroid hormones T3 and T4 are often also reduced in the blood. This is known as manifest hypothyroidism.
In many cases, this is accompanied by symptoms of hypothyroidism such as freezing, tiredness and weight gain. The most common cause is the thyroid disease Hashimoto. In most cases, special thyroid gland values in the blood are also elevated.
These are antibodies typical for Hashimoto, such as TPO antibodies and TG antibodies. In rare cases, hypofunction can also manifest itself in a reduction of the TSH value. This constellation, also known as central hypothyroidism, occurs when the pituitary gland is damaged, for example by an inflammation in the mother after the birth of a child.
The symptoms of hypothyroidism differ from those of hyperthyroidism. Roughly speaking, they form ,symptomatically speaking, the exact opposite: there is a lack of drive, weight gain, depression, fatigue, dry/rough skin and slow pulse (bradycardia). In addition, hair loss and cold intolerance can also occur.
Hashimoto’s thyroid disease usually leads to hypofunction with correspondingly reduced levels of the thyroid hormones T3 and T4 (thyroxine). The regulatory hormone of the thyroid gland (TSH) is usually elevated, as the body tries to increase hormone production in this way. However, especially at the beginning of the disease, a temporary hyperactivity with increased thyroid hormone levels and decreased TSH can occur.
Other specific blood values are decisive for the diagnosis of Hashimoto. These so-called thyroid gland antibodies are determined by the doctor if he suspects Hashimoto’s disease. In most patients, these are elevated.
The causes of hyperthyroidism can be different. In order to understand them, one must first look at the thyroid gland’s regulatory circuitry: The main task of the thyroid gland is first of all to produce the two hormones T3 and T4. These are then secreted into the body (more precisely: into the body’s bloodstream).The production of T3 and T4 is in turn controlled by a hormone called TSH.
TSH is the thyroid stimulating hormone. It stimulates – as the name suggests – the thyroid gland. A high TSH level requires a high production of T3 and T4.
But how do high TSH levels come about? This can occur naturally, for example, when the body feels that there is too little T3 and T4. This is the most favourable case and can be quite normal in certain life situations.
However, if the thyroid gland values are too high, this can also have other, more serious causes: For example, one speaks of thyroid autonomy when a part of the thyroid gland withdraws from the regulatory cycle and no longer reacts to the regulating TSH. This means that some gland cells of the thyroid gland produce hormones all by themselves and no longer listen to external signals. As a result, the T3 and T4 levels naturally shoot up, so the thyroid levels are much too high.
In order to counteract the overfunctioning, the production of TSH is reduced to zero by reflection to prevent the thyroid from producing. In the case of thyroid autonomy, as occurs with autonomous adenomas, this of course does not change the hyperfunction and high thyroid values. Extremely low TSH values in the laboratory together with clinical symptoms such as restlessness and nervousness represent the classic picture of an overactive thyroid gland, also called hyperthyroidism.
However, hyperthyroidism can also have other causes: Especially in iodine-deficient areas, the development of huge thyroid glands occurred in earlier years, some of which reached 100 times their normal size. Colloquially this phenomenon was called “goiter“, nowadays one knows rather the term “struma”. But how did it come about?
The thyroid gland needs iodine to produce its two hormones T3 and T4. To be exact 180-200 micrograms per day (i.e. 0.18 – 0.2 milligrams) for adults and adolescents. Even this small amount could not be achieved in the past in many iodine-poor areas.
In response, the thyroid gland has to increase its volume in order to reach the necessary thyroid levels with more cells. However, if a struma patient is suddenly administered a lot of iodine, for example in the form of medication or iodine-containing contrast medium, all thyroid gland cells are fired up, resulting in immediate hyperthyroidism. For this reason, the thyroid gland values must always be checked before contrast media are administered, as otherwise a potentially life-threatening metabolic condition is created.
Meanwhile, by the way, iodine is artificially added to many staple foods in Germany in order to ensure an adequate supply even in iodine deficiency areas. The best example is iodized table salt. The cause of acquired hypothyroidism, or hypothyroidism, is, as already mentioned, iodine deficiency.
It is the most common cause of avoidable mental developmental disorders (retardation) in children worldwide. If there is no substitution of iodine, the thyroid gland continues to grow, hoping to produce enough thyroid hormones with more tissue. However, even with growth alone, the low thyroid gland values cannot be compensated in the long term, so that a deficiency or hypothyroidism occurs.
In addition, the thyroid gland may be completely absent or only partially formed at birth. This can quickly become apparent when the child’s thyroid gland values are too low. One speaks of secondary hypothyroidism if there is nothing wrong with the thyroid gland itself, but the stimulating hormone TSH is not produced sufficiently by the pituitary gland in the brain. Hyperthyroidism and hypothyroidism can therefore merge and be mutually dependent.