Editing Thyroid (section)

====Nodules====

{{Main|Thyroid nodule}}
[[Thyroid nodule]]s are often found on the gland, with a [[prevalence]] of 4–7%.<ref name="Dean2008">{{cite journal | vauthors = Dean DS, Gharib H | title = Epidemiology of thyroid nodules | journal = Best Practice & Research. Clinical Endocrinology & Metabolism | volume = 22 | issue = 6 | pages = 901–11 | date = December 2008 | pmid = 19041821 | doi = 10.1016/j.beem.2008.09.019 }}</ref> The majority of nodules do not cause any symptoms, thyroid hormone secretion is normal, and they are non-cancerous.<ref name="Orlov2003">{{cite journal | vauthors = Welker MJ, Orlov D | title = Thyroid nodules | journal = American Family Physician | volume = 67 | issue = 3 | pages = 559–66 | date = February 2003 | pmid = 12588078 | url = http://www.aafp.org/afp/2003/0201/p559.html | access-date = 6 September 2016 }}</ref> Non-cancerous cases include simple [[cyst]]s, [[colloid nodule]]s, and [[thyroid adenoma]]s. Malignant nodules, which only occur in about 5% of nodules, include [[Follicular thyroid cancer|follicular]], [[Papillary thyroid cancer|papillary]], [[Medullary thyroid cancer|medullary]] carcinomas and [[metastasis]] from other sites.{{sfn|Davidson's|2010|p=744}} Nodules are more likely in females, those who are exposed to radiation, and in those who are iodine deficient.<ref name="Dean2008" />

When a nodule is present, [[thyroid function test]]s determine whether the nodule is secreting excess thyroid hormones, causing hyperthyroidism.<ref name="Orlov2003" /> When the thyroid function tests are normal, an [[medical ultrasound|ultrasound]] is often used to investigate the nodule, and provide information such as whether the nodule is fluid-filled or a solid mass, and whether the appearance is suggestive of a benign or malignant cancer.<ref name="Dean2008" /> A [[needle aspiration biopsy]] may then be performed, and the sample undergoes [[cytology]], in which the appearance of cells is viewed to determine whether they resemble normal or cancerous cells.{{sfn|Davidson's|2010|p=744}}

The presence of multiple nodules is called a [[multinodular goitre]]; and if it is associated with hyperthyroidism, it is called a [[toxic multinodular goitre]].{{sfn|Davidson's|2010|p=744}}