With this thyroid disease, there is a loss of the functional and growth interdependence of numerous pathologically changed thyroid cells on superordinate TSH control, leading to excessive thyroid hormone production due to the same (autonomy).
The elevated thyroid hormone level is detected by the healthy pituitary gland, which leads to inhibition of TSH secretion into the blood. The diminished TSH level halts the activity of the healthy thyroid gland sections, and in this way counteracts the hyperfunction as far as possible. This protective mechanism is highly effective, however it eventually breaks down with sustained growth and further cell reproduction of the autonomous cells. The result is clinically relevant hyperfunction.
The spatial distribution of the autonomous cells in the thyroid gland may manifest itself under scintigraphic examination as individual hot nodes (unifocal autonomy), as numerous hot nodes (multifocal autonomy), or as distributed evenly throughout the entire thyroid gland (disseminated autonomy), corresponding to a division of the disease into its three anatomical forms.
Autonomy occurs more often in older patients than in younger persons. In some geographical areas, the growth of autonomous cells is reinforced by a diet deficient in iodine.
Complaints resulting from autonomy cover a wide spectrum and are dependent on the number and function of the autonomous cells.
The most common symptoms with all forms of autonomy are:
- Rapid heartbeat
- Heavy sweating
- Hypersensitivity to heat
- Weight loss
Thyrostatic drugs such as Thiamazole, Carbimazole, Perchlorate (short-term)
Avoidance of large amounts of iodine (short-term)
Functional autonomy does not heal spontaneously. Therefore, with this disease, the autonomous regions of the thyroid gland should be surgically removed or permanently shut down using radioiodine therapy.
An operation is the preferred therapy option, in particular with:
Thyroid gland size above 80 ml, local complications such as pressure on the trachea or the esophagus with the simultaneous presence of multiple hot and cold nodes,
Suspicion of malignant changes, contradictions to radioiodine therapy, and the patient’s express wish for an operation.
Radioiodine therapy is the preferred therapy option with unifocal or multifocal autonomy without cold nodes and without suspicion of malignant changes.
Depending on the extent of the removed or deactivated thyroid regions, there could be thyroid hormone deficiency after an operation or radiotherapy. In such cases, lifelong medication with thyroid hormones (Levothyroxine) is required.
Radioiodine therapy may not be performed during pregnancy and breastfeeding due to the radiation exposure. Women of childbearing age should postpone becoming pregnant for six months after radiotherapy.
Thyrostatics: in cases of hyperthyroidism, therapy with thyrostatic medication (Thiamazole, Carbimazole, Perchlorate) should only be used for a short time, as a stopgap measure, before an operation or radiotherapy.
With manifest hyperthyroidism, the ideal option before an operation is to bring about normal thyroid metabolism (euthyroid metabolic state), and before radiotherapy mild hyperthyroidism (subclinical hyperthyroidism), by means of medication.
Beta-blockers: for the immediate control of cardiac and vascular complaints, for example rapid heartbeat and high blood pressure, beta-blockers such as Propranolol (Inderal) are used. They not only bring these complaints under control; they also have a sedative effect, which can be an advantage, given the restlessness caused by hyperthyroidism. In addition, they reduce the transformation that takes place in body tissue of T4 into the 10-times more effective T3, thus also increasing the effectiveness of T4 on tissue.
Avoiding iodine: at the beginning of therapy and before implementation of the definitive treatment of the thyroid gland using radioiodine therapy or an operation, large amounts of iodine should be avoided. High concentrations of iodine are found particularly in the contrast medium used in computer tomography and in medications such as Amiodaron. It is also recommended that foods containing iodine, such as fish, seafood, and cheese, should be avoided during the active phase of the disease (manifest hyperthyroidism). After surgical removal or deactivation of thyroid autonomy using radioiodine therapy, a diet low in iodine is no longer necessary.