What is the thyroid gland, and how common are its diseases?
The thyroid is a small, butterfly-shaped hormone gland located at the front of the lower neck, just in front of the windpipe. The thyroid hormones it produces (T3 and T4) regulate the body’s metabolic rate, heart rate, body temperature and energy balance. Thyroid diseases are very common in the population; they are several times more frequent in women than in men, and their frequency increases with age. Thyroid diseases are considered in three main groups: diffuse enlargement of the gland (goiter), nodule formation, and disturbed hormone production (hyperthyroidism or hypothyroidism). These three conditions may occur independently of one another or together in the same patient.
What are the symptoms?
Mild goiter and small nodules often cause no symptoms at all and are noticed incidentally during a routine examination or imaging. When the gland enlarges markedly, neck swelling, a feeling of fullness, difficulty swallowing, shortness of breath, a feeling of pressure that increases especially when lying on the back at night and sometimes hoarseness may occur. Hormone excess (hyperthyroidism) shows itself with palpitations, irritability, tremor, weight loss, heat intolerance, increased sweating and sleeplessness, whereas hormone deficiency (hypothyroidism) presents with findings such as weakness, weight gain, feeling cold, constipation, dry skin and forgetfulness. Because these symptoms develop slowly, patients may not notice them for a long time.
Causes and risk factors
The most common cause of goiter is iodine deficiency; however, since the use of iodised salt has become widespread, autoimmune thyroid diseases (Hashimoto’s thyroiditis, Graves’ disease) have come to the fore. A family history of thyroid disease, female sex, older age, previous radiation exposure to the head and neck region and the presence of certain autoimmune diseases are risk factors for the development of nodules and goiter. Thyroid nodules are extremely common; on ultrasound at least one nodule is found in a large proportion of adults, but the great majority of these are benign. Factors that increase the risk of malignancy in a nodule include radiation exposure in childhood, a family history of thyroid cancer, a hard, rapidly growing nodule, and accompanying hoarseness or a hard lymph node in the neck.
Diagnostic process
The assessment begins with a neck examination and a detailed medical history. To evaluate thyroid function, TSH and, when needed, free T3 and T4 levels are measured with a blood test; when an autoimmune process is suspected, thyroid antibodies are checked. The gold standard in imaging is thyroid ultrasound; with this method the size and structure of the gland, and the number and size of nodules and whether they carry suspicious features (such as irregular margins, microcalcifications or increased blood flow), are assessed. Nodules of certain sizes and features undergo ultrasound-guided fine-needle aspiration biopsy; the cell sample obtained is examined cytologically and the results are reported as benign, suspicious or malignant according to a standard classification system. With suspicious results, molecular tests or a repeat biopsy may come into consideration. In large substernal goiters (those extending into the chest), a CT scan may be requested to assess pressure on the windpipe.
Treatment options
Conservative and medical treatment
Benign, small nodules that cause no symptoms and mild goiter are usually just monitored with ultrasound at set intervals; no intervention is needed unless there is growth or a new suspicious finding. In patients diagnosed with hypothyroidism, lifelong hormone replacement therapy with a single daily dose of levothyroxine is given, and the dose is adjusted regularly with blood tests. In hyperthyroidism, treatment depends on the cause; in Graves’ disease, antithyroid medication, radioactive iodine therapy or surgery are considered. In toxic nodular goiter, if there is an inadequate response to medication, radioactive iodine or surgery comes into consideration.
Surgical treatment
Surgery is recommended in the following situations: cancer detected on biopsy or a strong suspicion of cancer; large goiters that press on the windpipe or the gullet and cause shortness of breath or difficulty swallowing; large goiters extending into the chest (substernal); toxic nodules resistant to medical treatment; and suspicious nodules that grow during follow-up. The operation is performed under general anesthesia through a small incision in the neck; part of the gland (lobectomy) or all of it (total thyroidectomy) may be removed. During the operation, protecting the nerves that control the vocal cords (the recurrent laryngeal nerves) and the parathyroid glands that maintain calcium balance is of great importance; in experienced centres the risk of damage to these structures is low.
Recovery and follow-up
After thyroid surgery the great majority of patients are discharged after spending one night in hospital. In the first days there may be mild pain and tightness in the neck and discomfort when swallowing, which usually eases within a few days. Temporary hoarseness is not uncommon and mostly resolves within a few weeks. If the whole thyroid has been removed, lifelong hormone replacement therapy is needed and the dose is adjusted at regular intervals with blood tests; if only one lobe has been removed, the remaining tissue can usually continue to produce enough hormone. In patients diagnosed with cancer, radioactive iodine therapy and regular oncological follow-up may be needed after surgery. For all patients, follow-up after surgery with blood tests at set intervals and, when needed, ultrasound is recommended.
Pregnancy and thyroid diseases
Normal thyroid function during pregnancy is very important both for the mother’s health and for the baby’s neurological development. Hypothyroidism diagnosed in pregnancy must be treated, and the dose should be reassessed with blood tests in each trimester; untreated hypothyroidism has been associated with a risk of miscarriage, developmental problems and pregnancy complications. For nodules newly detected in pregnancy, ultrasound can be used safely, and if considered necessary a needle biopsy can also be performed during pregnancy. If surgery is required, it is postponed to the second trimester where possible; if it is urgent, it can be performed safely at any stage of pregnancy. In the period after childbirth, some women may develop temporary thyroiditis; this typically runs a course of a hyperthyroid phase followed by a hypothyroid phase and most often resolves on its own.
What you should know about thyroid cancer
Compared with many other types of cancer, thyroid cancer is generally a group of diseases that progress slowly and respond well to treatment; in papillary thyroid cancer, the most common subtype, long-term survival rates are very high. When caught at an early stage, a cure can be achieved with surgery in a large proportion of cases. When the diagnosis is made, patients should, without undue anxiety, work through with their doctors an individual treatment plan shaped by the subtype, stage and spread of the cancer. After surgery, some patients receive radioactive iodine therapy, depending on the features of the disease, with the aim of clearing any thyroid tissue or microscopic disease that may remain. Long-term follow-up after treatment continues with blood tests (especially the thyroglobulin level) and periodic neck ultrasound.
Quality of life after surgery
The great majority of patients who have thyroid surgery lead a completely normal life with regular hormone monitoring and, when needed, replacement therapy. The scar left on the neck after surgery fades markedly over time; the incision is usually planned so that it is hidden in a natural skin crease. Most patients can return to their daily activities within a few days and to work and exercise at full capacity within a few weeks. Correct adjustment of the hormone dose is decisive for energy levels, weight control and general well-being; for this reason, it is important that blood test check-ups after surgery are not skipped.
Frequently asked questions
A thyroid nodule has been found – does this mean cancer? No. The great majority of thyroid nodules are benign. Ultrasound features and, when needed, needle biopsy are used to tell them apart definitively.
Is a needle biopsy painful and risky? The procedure is performed with a fine needle under ultrasound guidance; it usually causes only a mild pricking sensation, and the risk of a serious complication is very low.
Will my voice be affected after goiter surgery? In experienced hands the risk of permanent vocal cord damage is low; temporary hoarseness may occur and usually resolves on its own.
Will I have to take thyroid medication for life? If the whole thyroid has been removed or permanent hypothyroidism has developed, yes – hormone replacement therapy continues for life; taken regularly, this treatment preserves a normal quality of life.
What should I watch for while a small nodule is being monitored? It is important to attend check-up ultrasounds at the recommended intervals and to inform your doctor without delay if the nodule grows or develops a new suspicious feature.
What should I know about my calcium level after goiter surgery? Because the parathyroid glands can be temporarily affected during the operation, the calcium level is monitored after surgery and, if necessary, calcium supplements are given temporarily; this condition is mostly not permanent.
For the summary:
Back to the short articleThis article is for general information purposes only; please consult your physician for diagnosis and treatment.