The activity of the thyroid produces numerous effects in our body. For example, the thyroid regulates metabolism and controls very important functions, such as heart rate, development of the nervous system, body growth, muscle strength, sexual function and much more. Due to the central role of the thyroid gland in regulating the body's metabolism, when this gland does not function properly, the whole body suffers.
The causes of thyroid malfunction can be many. First of all, the thyroid can increase or slow down its activity, producing hormones in excess or in defect compared to the real needs of the body. These conditions are called, respectively, hyperthyroidism, ie an "excessive production of thyroid hormones, and hypothyroidism, which is the opposite condition, in which there is a deficiency of thyroid hormones.
In addition to these dysfunctions in the synthesis of hormones, the thyroid can also be affected by morphological alterations (therefore by changes in its shape, as in the case of goiters and nodules), or it can be the site of inflammation (which are thyroiditis) and tumors . Let's now see in detail all these conditions.
Hyperthyroidism (or overactive thyroid) is a condition in which the thyroid produces and secretes an excess of thyroid hormones. Precisely because thyroid hormones are responsible for controlling metabolism, hyperthyroidism causes an increase in many metabolic activities. This accelerated metabolism causes symptoms such as weight loss, tachycardia (a rapid heartbeat), nervousness, tremors, insomnia, muscle weakness, increased sweating, and heat intolerance. Sometimes, the hyperthyroid patient has evident signs even with the naked eye, such as the enlargement of the thyroid gland, called goiter, or the protrusion of the eyeballs that doctors call exophthalmos.
The causes of hyperthyroidism can be manifold. As we will see below, hyperthyroidism can be, for example, the consequence of a hyperfunctioning thyroid nodule or Graves 'disease (pronounced Beisdow). Graves' disease or syndrome is an autoimmune disease characterized by the production of abnormal antibodies that act like the TSH hormone, that is, they stimulate the thyroid to produce more hormones. I remind you that TSH is a hormone produced by the pituitary gland, located at the base of the skull. Through TSH, the pituitary gland controls the functions of the thyroid gland directly, stimulating its activity. If the thyroid is poorly functioning, the pituitary gland tries to compensate by secreting more TSH, vice versa if there are too many thyroid hormones in circulation the pituitary gland tries to rein in an overactive thyroid by reducing the share of TSH.
We speak of hypothyroidism when the thyroid does not produce an adequate amount of thyroid hormones for the body's needs. This leads to a reduction in metabolic processes and symptoms opposite to those we have just seen for hypothyroidism. For example, the hypothyroid subject complains of fatigue, slowing of reflexes, weight gain despite poor appetite and intolerance to low temperatures.
As for the causes of hypothyroidism, this condition may be due to problems that directly affect the thyroid gland (in these cases we speak of primary hypothyroidism) or to problems that alter the correct communication between the thyroid, hypothalamus and pituitary gland, as happens in the case of of an inappropriate secretion of TSH by the anterior pituitary which gives rise to a so-called secondary hypothyroidism.
Among the most common causes of hypothyroidism we remember first of all the iodine deficiency, but also autoimmune diseases of the thyroid gland such as Hashimoto's thyroiditis.
Hypothyroidism can also represent the outcome of surgery, irradiation of the neck or tumors of the pituitary or hypothalamus.
Another very common condition that can affect the thyroid is the so-called goiter. This term defines a generic increase in thyroid volume, which can be quite conspicuous at times.
Not all goiters are the same. For example, we have uninodular or multinodular goiters, that is, localized in one or more specific areas of the thyroid that resemble lumps. The so-called diffuse goiters, on the other hand, are characterized by the uniform enlargement of the entire gland.
The increase in thyroid volume can occur both in the case of hyperthyroidism and in the case of hypothyroidism. In addition, there are also goiters that do not modify the functionality of the thyroid gland at all, the so-called euthyroid goiters.
In addition to the cosmetic damage associated with the appearance of a bump on the neck, a bulky goiter can compress nearby organs, making it difficult to swallow or even breathe.
Another rather common problem that can affect the thyroid gland is the formation of so-called thyroid nodules. These are small lumps located on the thyroid that generally have a benign origin, ie they do not compromise its function, do not hide neoplasms and do not cause any symptoms to the individual. In any case, in the presence of thyroid nodules it is good to undergo specific tests to rule out possible future dysfunctions and to ascertain that it is not a tumor (which is a rare event, but still possible).
As for thyroid tumors, these can be both benign and malignant. As we have seen, in the majority of cases these are benign nodules, which do not cause symptoms, but which must still be kept under control. Malignant thyroid tumors are rare.
To conclude, another common thyroid disorder is so-called thyroiditis. The suffix -ite reminds us that we are talking about an inflammatory disease. Thyroiditis is therefore an inflammation of the thyroid gland.
The disease can have several causes, but the most common form is Hashimoto's thyroiditis. We have already seen this condition among the causes of hypothyroidism. I remind you that this is an abnormality of the immune system characterized by the production of antibodies that attack the cells of the thyroid itself, damaging them and consequently reducing the activity of the gland.
