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Thyroid Gland

 

Diseases of a thyroid gland

 

Where is the thyroid gland located?

The thyroid gland is a butterfly-shaped organ which is located beneath the larynx and in front of the trachea. This organ consists of a left and a right lobe and an intermediate connective tissue, known as isthmus, even though it weighs only 20g. The thyroid gland tissue is supplied through blood vessels from the large cervical arteries which open up in the upper and lower and centre of the gland into the tissue. Behind each lobe of the gland, an important nerve is attached, the “nervus laryngeus recurrens”. This nerve plays a crucial role in phonation by innervating the internal laryngeal muscles. It is difficult to find since it’s located behind and close to the left and right lobe of the thyroid. In the range of the thyroid capsule and the above mentioned nerves, one can find 4 so-called parathyroid glands next to the thyroid tissue, which are responsible for the regulation of the calcium metabolism.

Functions of the thyroid gland

Two different types of thyroid hormones are being produced in the thyroid tissue. Both of them play an important role in the regulation of our metabolism: the so called Thyroxin (T4) and the triiodothyronine (T3). They act on many cells and influence our energy metabolism. By that, our body demands a lot of iodine to produce these hormones. Iodine must be obtained by the intake of nutrients. In the thyroid tissue, the hormones are linked to proteins. If our body demands for those specific hormones, they simply bud off from the protein into our blood. In the blood T3 and T4 will again link themselves to carrier proteins to reach to their final destination. The demands for the thyroid hormones are controlled by a very complex regulatory circuit in which the hypothalamus and pituitary gland are included. If the amount of thyroid hormones decreases below the critical point, the hypothalamus and pituitary gland will release messengers to the thyroid, which will then increase the production of its hormones. If the amount of thyroid hormones rises in the blood, the brain suppresses the distribution of further thyroid hormones.

Most common diseases of the thyroid gland

If there is a lack of iodine in the body, the production of thyroid hormones will be insufficient. Through the regulatory circuit mentioned above, the hypothalamus is alarmed about the lack of thyroid hormones production. Therefore the hypothalamus sends out messengers to initiate the production of such hormones, However, because of the distribution of messengers, they thyroid gland will increase in size. If a shortage of iodine is a common state in the body, the thyroid tissue will increase even more in size and in volume. In addition to this, the tissue structure will change itself: Cysts, nodes and calcifications are developed. The enlarged thyroid gland is called “Struma” however the common name used for it is “goitre”. The Struma is one of the most common diseases of the thyroid. Another disease of the thyroid is an immunogenic hyperthyroidism also known as “morbus basedow”. In this case, stimulating antibodies are responsible for the constant overproduction of the thyroid hormones, which result to the so called hyperthyroidism. Physical symptoms are: swelling of the connective tissue behind the patients’ eye (endocrine orbitopathy), which over years can lead to a protruding eye. In addition the eye sight of the patients can jeopardize. Thyroid cancers are rare cases; however they should be mentioned here for the record.

How do I recognize a diseased thyroid gland?

A diseased thyroid gland may be undiscovered for over a long time, since the symptoms are mostly unspecific. The signs are caused by the production rate of thyroid hormones. In addition the signs can be influenced as well by the size increase of the organ. If an overproduction of thyroid hormones is the case, complaints about increased sweat outbreaks, heart rhythm disturbance, restlessness, and decrease in weight and hair loss are common in patients. However patients who suffer under a lack of thyroid hormones experience freezing, blockage, depressed and the feeling of being tired. If the organ increases in size, influenced by the Struma due to lack of iodine, patients endure a pressure in their necks. In rare cases the Struma may even narrow down the trachea and patients experience shortness in breath intakes.

Necessary clarifications and diagnostic possibilities

Mostly a diseased thyroid gland is being diagnosed as an additional finding during the routine check-up. If a diseased thyroid gland is being suspected, the physician has to carry out a questioning with the patient and search for any symptoms, caused by an over- or underproduction of thyroid hormones. Afterwards a manual examination of the thyroid gland is carried out: The physician stands behind the patient and feels with both hands how big the tissue of the thyroid is and its’ nature. Simultaneously the patient has to swallow, so that the physician can determine the mobility of the thyroid swallowing ability which is located in front of the trachea. In addition to this, various parameters are being defined from the blood of the patient: TSH value, which provides information through the diencephalon and the pituary gland, as well as T3 and T4, which shows how the body is supplied with thyroid hormones. If there is any reference of an immunogenic diseased thyroid or a malignant disease, additional examinations are made from the tissue structure and evaluation for a final determination of the disease. If any changes are found in the ultrasound or laboratory, an ultrasound has to be carried out of the thyroid. Therefore after some injections, “cold” and “warm” nodes in the thyroid tissue can be shown. If the local findings show a Struma large in volume, a radiograph from the soft tissues of the neck may be necessary to exclude a constriction of the trachea before the operation.

How can a diseased thyroid be treated?

A goiter with lack of iodine can be primarily treated through medicaments, by giving the patient thyroid hormones or supplementary iodine. Therefore the control circuit will be disturbed, which normally would signalise to the diencephalon the continuous lack of thyroid hormones. If nodes or cyst are already developed in the thyroid, only medicaments can slow down the growth of the thyroid. Larger struma or thyroids which show growing nodes are scaled down operatively. An immunogenic diseased Thyroid can be treated with a hormone blocker since in this case too many hormones are being produced. Another Therapy however would be the radioiodine therapy: Radioactive iodine 131 is being given to, whereby the cells of the thyroid are being destroyed. If a relapse should occur despite the medical treatment, surgery is the last and only solution. In occasion of thyroid cancer, the whole thyroid tissue and the corresponding lymph nodes are being removed through surgery. The following lines will describe the fundamental steps of the operation. The patient will be positioned on his back with a backwards hyperextended head. In the front of the base of the neck, at the point where the right and left collarbones almost touch each other, approx. one index finger length incision of the skin towards the chin will be carried out (Kocher incision). Afterwards the binding tissues and the flat neck muscles are being separated likewise the neck veins. The neck muscles are held aside with a hook. The surgeon concentrates now on the lobes of the thyroid. Depending on the disease and diagnostic findings, one lobe of the thyroid is being removed or even both of them. The connecting tissue will be carefully dissected from the lower lying thyroid capsule. The physician has to operate during theatre near the tissue and the thyroid capsule, so that he won’t injure the recurrence nerve, since this nerve innervates the vocal cords. With the use of a specialized instrument, the tissue bridge (isthmus) between the right and left thyroid lobe, will be hamstrung and removed. The lobe which has to be removed will then be excised carefully from the connective tissue of the lobes’ back. The blood vessels which perfuse the lobe will be suppressed. In the next step the pole vessels will be supressed as well. If the nerve and parathyroid are plainly identified and preserved, the diseased thyroid tissue can now be removed. Additionally, a thin drainage is inserted into the skin, so that the ichor and the residual blood can be eliminated. The skin muscle lobe will be sealed up through stitching, in result that afterwards, only a thin line-shaped scar is visible.

What happens after the treatment?

After the surgery, the surgeon will check on the operated area if there was any bleeding. As soon as the patient is awake and responsive, a voice trial is carried out to see whether the voice is hoarse. Using mirroring of the vocal cords, the neck-nose-ears doctor checks later if the vocal cords move equally on both sides. Any injured nerve is with 3 to 4 percent, the most common complication of a thyroid operation. Furthermore the calcium levels and the thyroid values, depending on the disease of the thyroid, are being checked. Especially the immunogenic thyroid diseases should be paid attention to, since the patient suffered of an over functioned thyroid. In general, the patient has to intake thyroid hormones and iodine in form of pills. The drainage will be removed 24 to 48 hours after the operation. The stiches in the skin are made of a resorbable material.

What has to be paid attention to in future everyday life?

Depending on the disese, the patient has to take continously medicaments. Whether in the form of iodine or thyroid hormones. It’s of great importance that blood values and binding tissues of the fundus oculli should be supervised especially in case of a immunogenic diseased thyroid. So that the physician can see if any new tissue has developed itself in the area where once the thyroid was removed.

 

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