What Causes Thyroid Nodules | UCLA Endocrine Center

Hello, I'm James Wu, an endocrine surgeon with the UCLA Health Endocrine Center. One common question I receive is about the causes of thyroid nodules.

First and foremost, it's crucial to recognize that thyroid nodules are much more common than previously thought. In the past, thyroid nodules were primarily detected through physical examination, with only a small percentage being palpable (able to be felt by the hands of the examining physician). However, the introduction of ultrasound technology has greatly enhanced our ability to visualize deep neck structures, including tiny thyroid nodules. In fact, if a random sample of healthy individuals underwent a neck ultrasound, nearly one-third would show thyroid nodules. Moreover, among individuals aged 50 or older, close to half would exhibit such nodules on imaging.

Why do we develop thyroid nodules?

As we get older, the chances of developing thyroid nodules rise. This is due to the gradual proliferation of abnormal cells within the thyroid gland over time. The buildup of these irregular cells results in the formation of nodules, a frequent occurrence as we age.

Another significant factor contributing to thyroid nodules is iodine deficiency, which can disrupt thyroid function and promote nodule formation. The thyroid gland relies on iodine to synthesize thyroid hormones, and inadequate iodine intake can lead to the development of nodules. However, in regions where iodine is added to salt as a public health measure, iodine deficiency-related nodules are rare. Hence, the labeling of iodinated salt in grocery stores serves as a reminder of its crucial role in thyroid health.

Additionally, studies have identified several lifestyle factors associated with thyroid nodules, including smoking, excessive alcohol consumption, and obesity. These habits have been linked to hormonal imbalances and inflammatory processes that may contribute to nodule development. Understanding the multifactorial nature of thyroid nodules underscores the importance of adopting healthy lifestyle practices and ensuring adequate iodine intake to support optimal thyroid function and minimize the risk of nodule formation.

Thankfully, most thyroid nodules are benign and do not require medical care. Furthermore, most patients with thyroid nodules have normal thyroid function, meaning that the thyroid gland continues to secrete thyroid hormone normally. When a new thyroid nodules is found, it's crucial to address two key concerns: Firstly, ensuring it lacks suspicious features indicative of thyroid cancer; and secondly, confirming it doesn't impede thyroid function. By prioritizing these evaluations, individuals can receive timely interventions if necessary and alleviate any potential concerns regarding thyroid health.

Key Insights:

  • Age is a significant factor in the development of thyroid nodules, with higher prevalence in older individuals.
  • Factors such as iodine deficiency, smoking, drinking, and obesity have been linked to the formation of thyroid nodules.
  • The majority of thyroid nodules are benign and do not cause any problems with thyroid function.
  • Proper diagnosis and evaluation are crucial to determine if a nodule is suspicious for cancer or affecting thyroid function. Regular check-ups and follow-ups are important.

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