Updated 5 July 2022 A thyroid with nodules is technically called a nodular goitre. Thyroid nodules are more frequent in females and their prevalence increases with age. With the use of ultrasound examination, it is possible to identify thyroid nodules in more than 50% of all women aged over 50. How are thyroid nodules characterised? Various types of nodules may develop in the thyroid; they can be classified as: Benign - benign nodules may be cysts, nodular hypoplasia (colloidal) or adenomas; Malign - also known as thyroid cancer or carcinoma. A nodule is malignant when it has the capacity to invade other structures outside the physical limits of the gland. These nodules are uncommon , occuring in 5 % of people with nodular goitre. Thyroid carcinoma has various forms, with papillary carcinoma being the most common . In most cases, is the least aggressive. What are the causes of thyroid nodules? There is no single cause of thyroid nodules. Factors that can contribute to their emergence include: Iodine deficiency; Genetic changes (which may be transmitted through generations); Thyroid inflammation; Exposure to radiation in childhood. What are the symptoms of thyroid nodules? Most thyroid nodules do not cause symptoms. The nodules are often identified during routine medical exams performed due to other reasons. Symptoms, where present, are due to thyroid malfunctioning or to the organ excessive volume. Some nodules produce excessive amounts of hormones and are called toxic or hyperfunctional, being associated with: Palpitations; Weight loss; Tremors; Anxiety; Heat intolerance. These nodules are very rarely malignant. Very bulky nodules can compress the adjoining neck structures , leading to, among other things: Hoarseness; Difficulty breathing; Difficulty swallowing. Diagnosis of thyroid nodules It is always for the doctor to decide whether there is a need for a particular test, depending on the individual characteristics and needs of each person. In general, 3 types of examinations are performed in the diagnosis of thyroid nodules: 1 - Blood tests Levels of thyroid hormones (thyroxine or T4 and triiodothyronine or T3) and the pituitary hormone regulating the thyroid function (thyroid stimulating hormone or TSH) are determined in the blood. When one or more nodules are producing to excess, hyperthyroidism can arise. This results in lower than normal TSH levels and, possibly, increased T3 and/or T4 levels. These tests can be carried out without the need for fasting. 2 - Neck ultrasound Neck ultrasound allows us to: Assess the size of the nodules; Identify whether they are single or multiple; Elucidate on the risk of malignancy (although it does not allow a definitive diagnosis); Assess the lymph nodes. This is a high precision , relatively economical, painless and harmless test, since it does not involve exposure to radiation. 3 - Fine needle aspiration cytology (FNAC) The examination that allows for greater approximation to a final diagnosis is aspiration cytology with a fine needle: This consists of the collection of cells from the nodule for microscopic analysis ; Cell collection is carried out by puncturing the nodule with a very fine needle ; It is a procedure that is generally painless, very fast , similar to an injection, by which the cells needed for diagnosis are aspirated; Its main objective is to identify malignant nodules . However: Sometimes not enough cells are collected to make a diagnosis. It therefore becomes necessary to think about repeating the test ; It is possible for the diagnosis to be inconclusive; in other words, cytology cannot definitively confirm whether the nodule is benign or malignant. In some of these situations it is safer to opt directly for surgery; As with the general medical examination, cytology is not wholly reliable . So, even nodules with a benign cytology should be monitored; Not all nodules should be subject to cytology testing. This examination should not be carried out on nodules measuring less than 1 cm/1.5 cm , particularly if the risk of malignancy is low according to their clinical and ultrasound characteristics; When the thyroid has multiple nodules, cytology should be carried out on the nodules considered more suspicious. Cytology should be ultrasound-guided . Therefore, it is very important that the doctor carrying out this examination is familiar with thyroid disease. Even a diagnosis of malignancy by this method will require confirmation by analysing the entire nodule under the microscope (histological examination) after surgery. Other examinations, such as thyroid scintigraphy or computerised tomography (CT) , should only be performed in specific situations. Why should thyroid nodules be assessed? Thyroid nodules should be medically assessed principally in order to: Investigate whether the thyroid is working normally; Identify the possible existence of a malignant tumour. Thyroid nodules and thyroid carcinoma: what’ is the relationship between them? A diagnosis of thyroid carcinoma almost always comes about following the assessment of a painless thyroid nodule. There are various signs and symptoms that can lead to the suspicion that a nodule is malignant , but they are by no means definitive: Progressive growth; Hoarseness; Nodule hardness; Presence of increased lymph nodes. What is the treatment for thyroid nodules? In most cases, drug treatment is largely ineffective in reducing the volume of thyroid nodules. Surgery is indicated when: The nodule is malignant; There is a suspicion of malignancy ou the citology is not conclusive; The size of the nodules leads to respiratory, deglutition ou aesthetic disorders. Iodine-131 therapy (radioactive iodine) should be considered when the nodule produces an excess of hormones and after surgery of a malignant tumor to kill resicual cells. Iodine-131 acts differently in benign nodules and thyroid carcinoma, and, therefore, there is no need for admittance to hospital in the first case. Endocrinology and General Surgeru are the medical specialities dealing with thyroid diseases. This article was written with the support of physicians and other clinical professionals from the Hospital da Luz network. The content published in the Health Guide is intended for the general public and is provided for informational and educational purposes only. It does not replace individual medical assessment, diagnosis, or personalized clinical advice from a qualified healthcare professional. The content is produced or reviewed by physicians and other healthcare professionals at Hospital da Luz and is based on the knowledge available at the time of publication or the most recent update, as indicated at the beginning of each item.
