Goiter & Multinodular Goiter Overview Causes & Treatment
A goiter is defined as an enlarged thyroid. It can be a simple goiter which is when the thyroid is bigger than normal or a multinodular goiter in where there are multiple nodules throughout the thyroid. It is uncertain what exactly causes multinodular goiters. In some cases little iodine in the diet and genetic factors have been shown to lead to multinodular goiters. Multinodular goiters can be classified as toxic when the thyroid produces too much thyroid hormone causing hyperthyroidism or non-toxic, when the thyroid hormone remains normal.
Multinodular Goiter Symptoms
Usually multinodular goiters do not cause any symptoms and are picked up on a routine physical exam. If a goiter is very large patients may have compressive symptoms such as difficulty breathing, difficulty swallowing (choking sensation), or swelling or fullness in the neck. These symptoms are more common when the goiter is growing into the chest called a substernal goiter. Patients with a toxic multinodular goiter will have signs and symptoms of hyperthyroidism.
Evaluation of Multinodular Goiters
The work up of a multinodular goiter begins with history and physical exam.
- How fast is the thyroid growing?
- Does the patient have risk factors for thyroid cancer such as a family history or exposure to radiation?
- Does the patient have a family history of goiter?
- Are compressive symptoms present such as hoarseness, difficulty swallowing or difficulty breathing or lying flat?
- Does the patient have any symptoms of hyperthyroidism?
On physical exam the size and texture of the gland is important. It is also important to look for signs that the gland may be growing down into the chest.
Following a complete history and physical exam, the thyroid is further evaluated using ultrasound (USG). This test gives more details about the size and appearance of the thyroid. It also allows for the precise measurement of any thyroid nodules and whether they are cystic (fluid contained) or solid. The ultrasound is also used to describe the features of each nodule such as the character of the borders, and whether there are any calcifications.
Multinodular Goiter Biopsy
In patients who are found to have a nodule that is greater than 1 cm in size, or patients with smaller nodules that harbor worrisome ultrasound characteristics (calcification, irregular borders), a biopsy is recommended. This is usually accomplished using a technique called fine needle aspiration. Under ultrasound guidance, the physician aspirates cells from the nodule using a 21 or 25 gauge needle (a little typically smaller than the one used to draw blood). The purpose of the needle aspiration is to identify nodules that may be cancer. Once the biopsy has been obtained, the cells are placed on class slides and reviewed by a cytopathologist. Most pathologists use the Bethesda classification system to categorize the biopsy findings.