HASHIMOTO'S DISEASE

Hashimoto's disease is a disease characterized by inflammation of the thyroid gland resulting from a disorder of the immune system. It was given this name because it was described by the Japanese scientist Hakaru Hashimoto at the beginning of the 20th century. In Hashimoto's disease, which is one of the autoimmune diseases, the thyroid gland is perceived as a foreign tissue by the immune system. As a result of the immune system losing its tolerance to its own tissues and not being able to recognize its own, the development of antibodies in the blood causes deterioration in the structure of the thyroid gland and inflammation. These antibodies cause a war in the thyroid gland, and over time, the gland shrinks and its functions decrease.

Hashimoto's disease is one of the diseases that cause insufficiency of the thyroid gland (hypothyroidism). 2% of the population is affected by this disease and 95% of the patients are women. It is 6-10 times more common in women than men. It can occur at any age, especially between the ages of 30-50.

Risk factors

Although the factor that initiates this disease is not known exactly, familial and genetic disposition is of great importance. If it is present in one of the family members, it tends to be seen in other people as well. Therefore, in individuals with Hashimoto's disease, it is important to follow up other members of the family in terms of disease risk. However, studies conducted in regions with high iodine intake such as the USA and Japan show that the frequency of Hashimoto's disease increases as iodine intake increases. For this reason, excess iodine intake, which is essential for thyroid hormone production, can cause harmful effects. Another factor that can trigger the development of Hashimoto's disease is radiation exposure. Radiation therapy (radiotherapy) to the neck area is an important risk factor for the development of thyroid diseases.

Symptoms

Hashimoto's disease is generally a slow-onset and insidious disease, and signs and symptoms progress within months. Initially, the patients did not have any complaints, and during the controls, elevations in hormones such as TSH or only antibodies such as anti-TG and anti-TPO can be detected (thyroid hormones such as free T3 and free T4 are usually normal at this stage). On the other hand, in patients who are not treated for a long time, symptoms ranging from complaints such as fatigue, constipation, dry skin and weight gain to coma can be seen. Weight gain usually develops due to fluid collection in the tissues. These symptoms may be accompanied by deepening of the voice, feeling cold easily, menstrual irregularities, hair loss, decreased thinking function and memory loss. Especially in women, decrease in the frequency of menstruation, breakthrough bleeding, infertility and sexual reluctance are common findings.

How is the diagnosis made?

In the presence of the aforementioned symptoms, the diagnosis of Hashimoto is made by looking at TSH and thyroid hormones (free T4 and T3) together with thyroid antibodies (anti-Tyroglobulin, anti-Thyroid Peroxidase) in the blood. While the thyroid hormones are normal, the increase in TSH indicates the initial stage of the disease, and the increase in TSH together with the decrease in the thyroid hormones indicates the progression of the disease. In Hashimoto's patients, 95% of anti-thyroid peroxidase antibodies and 60% of anti-thyroglobulin antibodies are positive. In some patients, while all hormones, including TSH, are normal, antibodies may be high. This is an indication of genetic predisposition for Hashimoto's disease and requires careful follow-up. However, it should be kept in mind that antibodies may be normal in 10% of Hashimoto's patients. Antibodies are generally important indicators during the diagnosis, but there is no clinical significance in their follow-up.

Although signs of coarsening and inflammation in the thyroid gland can be seen in the thyroid ultrasonography in the diagnosis of Hashimoto's disease, they are not essential for the diagnosis. However, ultrasonographic imaging has an important place in the evaluation and follow-up of nodules that may develop on the background of this disease.

If nodules are not present in Hashimoto's disease, thyroid biopsy (examination of the tissue for cancer cells by taking a piece from the thyroid gland) has no place.

Treatment

The treatment of Hashimoto's disease, like the treatment of other diseases that cause thyroid failure, is done by replacing the missing thyroid hormone. The drug dose required by each patient should be administered by experienced physicians with a TSH of 0.5-2.5 IU/L. Since thyroid drugs can cause absorption problems, care should be taken not to take them together with iron or vitamin pills.

Even without hypothyroidism, patients with goiter benefit from drug therapy and the goiter gets smaller. In pregnant patients, the dose requirement may increase up to 50%. Although there is no serious decrease in thyroid hormones, patients with high antibodies can also benefit from small-dose drug therapy. Spontaneous resolution of Hashimoto's disease is very unlikely, and these patients usually require lifelong drug therapy.

It is out of question for Hashimoto patients to be operated on unless nodules or thyroid cancer are detected. In the course of Hashimoto's disease, unreal, false nodules can be seen and have no clinical significance. However, the frequency of thyroid lymphoma increases in Hashimoto's disease, although it is not common. For this reason, in the presence of true nodules, these nodules should be followed carefully ultrasonographically and, if necessary, biopsy should be performed to show that they are benign nodules.

Hashimoto and Pregnancy

Hashimoto's disease can prevent pregnancy by causing thyroid hormone deficiency, disrupting the menstrual cycle and reducing egg quality. However, although pregnancy may occur in women with hormone deficiency in some cases, this situation carries great risks especially for the fetus in the mother's womb. Thyroid hormone insufficiency may cause miscarriage, as well as mental retardation and developmental disorders in the nervous system may occur in the fetus in case of survival. Pregnant women are faced with many risks, from gestational blood pressure to severe postpartum bleeding, from delayed delivery to inability to breastfeed. For these reasons, it is very important to evaluate thyroid tests before pregnancy in women who are planning pregnancy, and to follow up closely throughout pregnancy if a problem is detected and medication is started.

Prof Dr Mahmut Muzaffer Ilhan

Endocrinologj and Metabolism Disease