Excellencies - Diabetology and Endocrine Diseases

The Thyroid

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Thyroid diseases derive from dysfunctions of the thyroid gland, an endocrine gland at the base of the neck that produces thyroid hormone, in the form of tyrosine (T4) and triiodothyronine (T3).
Thyroid hormones regulate numerous functions of metabolism, including lipolysis at the adipose tissue level, protein synthesis and the production of glucose from the liver glycogen, as well as the development of the central nervous system and body growth (1, 2).
The production of an adequate quantity of thyroid hormones is therefore indispensable for normal body growth and for the development and maturation of the various systems.
The correct function of the thyroid gland is guaranteed by an adequate nutritional intake of iodine. Iodine, in the form of iodide, is absorbed by the thyroid gland and chemically combined with the amino acid tyrosine to synthesize the thyroid hormone.
The daily intake of iodine required is estimated at 150 ug/day. However, the presence of this element in food and water is very variable and often too low compared to human needs.

Iodine deficiency, one of the most serious public health problems according to World Health Organization estimates, results in several diseases, more or less serious depending on age and sex, such as hyper (hyperthyroidism) or thyroid hormone hypoproduction (hypothyroidism) by the gland, or the uni or plurinodular goiter (3).
Hypothyroidism is a condition characterized by the presence of bradycardia, stress dyspnea or sleep apnea often associated with asthenia and constipation, pale, cold and dehydrated skin, constipation, until the appearance in young women of irregularities in the menstrual cycle (4).
Hypothyroidism is frequently caused by autoimmune thyroiditis, medication or iodine deficiency.
Hyperthyroidism, on the other hand, manifests itself with signs and symptoms diametrically opposed to those of hypothyroidism: specifically, people who suffer from hypothyroidism complain of tachycardia, profuse sweating, hot skin and weight loss, which is often associated with diarrhea. The most common cause of hyperthyroidism is Graves’ disease (GD), followed by toxic nodular goiter (TMNG), whose prevalence increases with age, especially in regions of iodine deficiency (5).
A thyroid hormone deficiency during fetal life has serious consequences on intellectual development, leading to mental retardation, deaf-mutism and spastic paralysis (hypothyroidism in pregnancy).

The need for iodine is therefore particularly high for pregnant women and children.
Iodine deficiency is the cause of a chronic increase in TSH values (pituitary hormone that regulates thyroid hormone synthesis), which in turn induces hyperplasia and hypertrophy of the thyroid gland which results in the appearance of the thyroid goiter.
Within the thyroid goiter it is sometimes possible to find nodular lesions which, depending on their ability to synthesize thyroid hormones, are divided into hot or cold nodules. The latter are more frequently associated with an increased incidence of thyroid malignancies (6, 7).
It is necessary, for the prevention of thyroid diseases, that the daily intake of iodine with food is supplemented. The use of iodised salt makes it possible to cover the daily requirement by providing 30 μg of iodine per gram of salt. The WHO recommends maintaining daily salt consumption at 3-5 g for the risk of cardiovascular disease (8).

To reduce the risk of thyroid disease, however, in addition to iodine-prophylaxis, the role of the endocrinologist is essential. At the Endocrinology clinics of the MultiMedica Hospital it is possible to carry out a specialist examination with the endocrinologist, who also collaborates with a multidisciplinary team (radiologist, nuclear physician, ENT surgeon) in order to identify and treat the main thyroid alterations at an early stage.
In our laboratories, blood samples can be taken quickly in order to identify conditions of dysthyroidism worthy of treatment. In our Centre it is also possible not only to perform biohumoral examinations, but also to carry out instrumental investigations such as neck ultrasound, thyroid scintigraphy and needle aspiration (FNAB) eco-assisted, with the possibility to consult the cytological reports directly online, so as to shorten the time needed to intervene through a thyroidectomy surgical approach.
Thyroid ultrasound is recommended in all patients with goiter or palpable thyroid nodules in order to assess the size and morphology of the gland and the possible coexistence of non-palpable lesions, to highlight phlogistic phenomena or characters suggestive of altered thyroid function, to document ultrasound characters suggestive of malignancy and to select the nodules to be submitted to FNAB in the context of multi-nodular goiters, and finally to check the variation in the size of the thyroid gland or its lesions during the follow-up (9).
Ultrasound study of the neck is also necessary in patients with an indication for thyroidectomy or radioiodine treatment. In cases of surgical indication on suspicion of malignancy, ultrasound provides important information on lesion size, possible extra-capsular growth, multifocal/bilaterality of lesions and presence of secondary adenopathies. This data is essential for proper planning of thyroidectomy surgery by our ENT surgeons.

Bibliography:

  1. Molina P. Fisiologia Endocrina. Lange Physiology Series. McGraw-Hill, 2004: 84-8.)
  2. Yen PM. Physiological and Molecular Basis of Thyroid Hormone Action. Physiol Rev 2001, 81: 1097-142.
  3. www.epicentro.it
  4. Brent GA, Reed-Larsen P, Davies TF. Hypothyroidism and thyroiditis. In: Williams Textbook of Endocrinology, Kronenberg, HM et al Eds, Philadelphia: Saunders, Elsevier 2008: 377–409
  5. Ross DS, Burch HB, Cooper DS, et al. 2016 American Thyroid Association Guidelines for diagnosis and management of hyperthyroidism and other causes of thyrotoxicosis. Thyroid 2016, 26: 1343-421.
  6. www.issalute.it/index.php/la-salute-dalla-a-alla-z-menu/m/malattie-della-tiroide
  7. Gharib H, Papini E, Garber JR, et al, on behalf of the AACE/ACE/AME Task Force on Thyroid Nodules. American Association of Clinical Endocrinologists, American College of Endocrinology, and Associazione Medici Endocrinologi medical guidelines for clinical practice for the diagnosis and management of thyroid nodules. Endocr Pract 2016, 22 suppl 1: 1-60.
  8. Ramelli F, Studer H, Bruggisser D. Pathogenesis of thyroid nodules in multinodular goiter. Am J Pathol 1982, 109: 215
  9. Cooper DS, Doherty GM, et al. Revised American Thyroid Association management guidelines for patients with thyroid nodules and differentiated thyroid cancer. Thyroid 2009, 19: 1167.