I. Hyperthyroidism
1. Concept: Thyrotoxicosis refers to a group of clinical syndromes in which excessive thyroid hormones in the blood circulation cause increased excitability and hyper-metabolism in the nervous, circulatory and digestive systems. The thyrotoxicosis is caused by hyperthyroidism (hyperthyroidism), where the thyroid gland itself is hyperfunctioning, resulting in increased synthesis and secretion of thyroid hormones; the thyrotoxicosis is caused by inflammation of the thyroid follicles (e.g., subacute thyroiditis, quiet thyroiditis, postpartum thyroiditis, etc.), and excess thyroid hormones stored in the follicles enter the circulation. Thyrotoxicosis is called destructive thyrotoxicosis, and the thyroid gland in this condition is not hyperactive.
2. Classification: Types of hyperthyroidism include: 1) Graves’ disease; 2) multinodular goiter with hyperthyroidism; 3) iodine hyperthyroidism with autonomic hyperfunctional thyroid adenoma; 4) pituitary hyperthyroidism; 5) differentiated thyroid cancer with hyperthyroidism; 6) iodine hyperthyroidism; 7) thyroiditis with hyperthyroidism; 8) various other tumors with hyperthyroidism. Among them, Graves’ disease is the most common, accounting for about 85% of all hyperthyroidism.
3. Etiology: The etiology and pathogenesis of hyperthyroidism, especially Graves’ disease, have not yet been fully elucidated. According to the research in the past 20 to 30 years, it is proved that the disease is mainly caused by the autoimmune reaction induced by stress factors such as mental stimulation on a genetic basis. The main etiological factors are.
Genetic: there are genetic susceptibility factors involved in the disease and some patients can have someone in their family suffering from thyroid disease.
Increased iodine intake: some data show that there is a great difference in the prevalence of hyperthyroidism in iodine-rich and iodine-deficient areas, with the former being 2-3 times higher than the latter. Data from epidemiological studies at home and abroad show that the incidence of thyroid autoimmune diseases, which include hyperthyroidism, increases after universal iodine supplementation.
Mental factors: including increased work pressure, competition, mental trauma and infection, etc. Clinical observation shows that many white-collar women are currently suffering from hyperthyroidism, which is related to the pressure of competition in the workplace. Basic research shows that viral infections are closely related to the development of hyperthyroidism.
Thyroiditis
1. Concept: Thyroiditis is a thyroid disease with inflammation as the main manifestation, including infectious and non-infectious. The clinical manifestations are inconsistent, and the thyroid gland can manifest as hypofunction to enlarged thyroid gland and symptoms similar to hyperthyroidism. It may be accompanied by systemic reactions of varying degrees.
2. Classification: The main categories are: 1) Hashimoto’s thyroiditis; 2) subacute thyroiditis; 3) resting (painless) thyroiditis; and 4) acute infectious thyroiditis. Hashimoto’s thyroiditis and subacute thyroiditis are more common clinically, while resting thyroiditis is insidious and usually occurs during pregnancy.
The cause of thyroiditis varies.
The thyroid gland appears diffusely enlarged, sometimes with multiple hard nodules, and can be easily confused with thyroid cancer. Serum TgAb and TmAb are often seen to be elevated. Patients often have hypothyroidism, which is permanent.
Subacute thyroiditis is most often associated with respiratory infections and is preceded by a history of various viral infections. Some patients may have transient hypothyroidism with mild symptoms, and some patients may have short-term manifestations of thyrotoxicosis; permanent hypothyroidism is rare.
Quiescent thyroiditis is a variant of Hashimoto’s thyroiditis that is short-lived and self-limiting, with mild and transient hyperthyroidism followed by transient hypothyroidism that eventually returns to normal on its own. The disease is usually more frequent during pregnancy and recovers on its own after delivery.
Symptoms of acute infectious thyroiditis include thyroid pain, painless enlargement of the thyroid gland and hypothyroidism, which is a systemic infectious disease involving the thyroid gland.
Three, hypothyroidism
1. Concept: Hypothyroidism, referred to as hypothyroidism, is a syndrome caused by insufficient synthesis, secretion or biological effect of thyroid hormones.
2, classification: mainly divided into.
Primary hypothyroidism, including congenital thyroid dysplasia, various types of thyroiditis, endemic iodine deficiency and postnatal thyroiditis caused by hypothyroidism.
Medical hypothyroidism, which includes hypothyroidism caused by anti-thyroid drugs, radioactive iodine 131, and thyroid surgery.
Secondary hypothyroidism, which is caused by a decrease in thyrotropic hormone (TSH) and/or thyrotropin-releasing hormone (TRH) due to pituitary and/or hypothalamic lesions.
Peripheral hypothyroidism, including hypothyroidism caused by thyroid hormone receptor and post-receptor defects that prevent normal application of thyroid hormones.
3. Etiology: mainly includes.
Destruction of thyroid cells leading to reduced synthesis and secretion of thyroid hormones, seen in various lesions of the thyroid gland itself, such as taking anti-thyroid drugs, various types of thyroiditis, after major thyroidectomy for hyperthyroidism or thyroid cancer, after radioactive iodine 131 treatment, congenital thyroid deficiency, and endemic iodine deficiency.
Upstream lesions due to pituitary or hypothalamic lesions are generally rare and can be seen in pituitary tumors, Sheehan’s syndrome, non-neoplastic selective TSH deficiency, stroke, after pituitary surgery or radiation therapy to the pituitary site, suprasellar tumors, and congenital TRH deficiency.
Terminal resistance to thyroid hormone action nuclear receptor deficiency, impaired binding of T3 or T4 receptors, and post-receptor defects.
IV. Thyroid tumors
1. Concept: Thyroid neoplasms (thyroidneoplasms) or thyroid nodules are common and frequent clinical diseases. In terms of gender, the incidence of thyroid tumors in women is 2-4 times higher than that in men.
2. Classification: According to benign and malignant, thyroid adenoma and thyroid cancer can be classified. Adenoma can be further classified according to its function as
Simple thyroid adenoma, which does not cause hyperthyroidism and is a “warm” or “cold” nodule on thyroid scan.
High-functioning adenomas, also known as toxic thyroid adenomas, are simple adenomas that increase in functional autonomy over time, resulting in increased synthesis and secretion of thyroid hormones and suppression of TSH secretion by the pituitary gland, resulting in “hot” nodules on thyroid scans.
As the adenoma grows larger, it may become hemorrhagic, degenerative, necrotic, or cystic, and the thyroid scan may show a “cold” nodule with loss of function.
In addition to benign thyroid adenomas, a small percentage of thyroid tumors are found to be thyroid cancer, which can be classified by pathological type.
Papillary carcinoma, which is the most common type of well-differentiated thyroid cancer, accounts for about 80% of all thyroid cancers and is less malignant and can be cured by surgery and iodine 131 treatment.
Follicular carcinoma, which accounts for 10%-15% of all thyroid cancers, easily penetrates the envelope and enters the vein to form a thrombus, which often becomes the starting point of distant metastasis, so follicular carcinoma is mostly seen in bloodstream metastasis, which accounts for 19%-25% in literature.
Medullary carcinoma, also known as C-cell carcinoma, is a moderately malignant tumor. It is often associated with systemic symptoms, and about 30% of patients have a history of chronic diarrhea and facial flushing resembling carcinoid syndrome, or cushing metabolic syndrome, which is related to tumor cell products.
Undifferentiated carcinoma, which is highly malignant, grows rapidly and often invades surrounding tissues and distant metastases at an early stage.
Etiology: The etiology of thyroid tumor is not very clear, it may be related to dietary factors (high iodine or iodine deficiency diet), history of exposure to firing line, increased estrogen secretion, genetic factors, or other benign thyroid diseases such as nodular goiter, hyperthyroidism, thyroid adenoma, especially chronic lymphocytic thyroiditis.