Fullscript Academy

Thyroid dysfunction can be categorized as primary or secondary. Primary hypothyroidism occurs when there's a dysfunction in the thyroid gland itself and it isn't able to produce adequate levels of thyroid hormone. Secondary hypothyroidism, also known as central hypothyroidism, occurs when there's a dysfunction in communication with the thyroid gland via the hypothalamus-pituitary axis. (Gaitonde 2012) 

While there are many potential causes for primary and secondary hypothyroidism, autoimmunity is the most common cause of primary hypothyroidism. (Nygaard 2014) Autoimmunity can lead to autoimmune hypothyroidism or Hashmito’s thyroiditis, which will be the focus of this article. Autoimmunity can also lead to autoimmune hyperthyroidism or Grave’s disease. 

Given that autoimmunity is the most common cause of primary hypothyroidism, identifying it is the key for optimal thyroid health management.

Given that autoimmunity is the most common cause of primary hypothyroidism, identifying it is key for optimal thyroid health management. 

Contrasting primary hypothyroidism and Hashimoto’s 

Given that Hashimoto's disease is a cause of hypothyroidism, it precedes primary hypothyroidism and can eventually develop into overt hypothyroidism. However, it's possible to have Hashimoto’s disease without developing hypothyroidism if the autoimmune response doesn't significantly impair thyroid function. Conversely, a diagnosis of hypothyroidism can occur without having Hashimoto's since there are many other causes of primary hypothyroidism. (Allarakha 2022) Other causes of primary hypothyroidism include congenital anomalies, nutrient deficiencies, infiltrative cardiomyopathies, and chronic and various iatrogenic factors such as thyroid surgery, radioiodine therapy, and neck radiation. (Gaitonde 2012)

The importance of a comprehensive assessment

A comprehensive assessment of thyroid function ruling out an autoimmune process is crucial for designing a holistic patient treatment plan. Including autoimmune markers in the assessment of thyroid function can uncover underlying etiologies, such as Hashimoto’s disease, which may not be apparent through standard thyroid function tests alone. Furthermore, considering the clinical picture and patient symptoms is essential, as certain causes of hypothyroidism, like thyroid hormone resistance, may not be detected in blood work. Therefore, it's important to consider several factors in the evaluation of a patient with hypothyroidism to ensure comprehensive treatment, beyond just lab values. 

(NIDDK 2022)(Wilson 2021)

Patient history and physical exam findings 

Since thyroid hormone governs the metabolism of all of our cells, diverse system effects are possible. (Mincer 2023) 

On palpation, the thyroid can feel firm in Hashimoto’s thyroiditis, malignancy, and benign and malignant nodules. (Thyroid Exam 2024) A thyroid ultrasound may be helpful in further assessing thyroid nodules, goiter, and thyroiditis. 

Additional considerations

Several medications, herbs, and environmental toxins have been noted to inhibit thyroid function. It’s important to consider whether these may be contributing to a patient’s picture and whether the prescribing doctor needs to modify them to improve thyroid function.  

Environmental toxins

Environmental toxins, such as heavy metals (e.g., cadmium, lead, and mercury) and certain chemicals (e.g., bisphenol A, phthalates, and perchlorate), can disrupt thyroid function by interfering with hormone production, transport, and metabolism. These toxins are often ubiquitous in the environment due to industrial processes, pollution, and everyday exposure to consumer products. Identifying and measuring levels of these environmental toxins in individuals with hypothyroidism can provide valuable insights into potential contributing factors to thyroid dysfunction. 

Medications

Certain medications can interfere with thyroid function at various stages of hormone production and utilization. For instance, drugs like lithium carbonate, sulfonamides, sulfonylureas, and tyrosine kinase inhibitors can affect the synthesis of thyroid hormones. (Sarne 2016)(Torino 2009) Others, such as amiodarone and androgens, can lower levels of triiodothyronine (T3). (Torino 2009)(Wang 2015) Beta blockers are known to reduce the conversion of thyroxine (T4) to T3 in peripheral tissues, while interferons and interleukin-2 have been linked to autoimmune thyroid disease. (Schraga 2002)(Torino 2009) Furthermore, high doses of thyroid replacement hormone can suppress the body's natural thyroid hormone production. (American Thyroid Association 2020)

Herbs 

Some studies have suggested that Lycopus virginicus, Lycopus europaeus, Melissa officinalis, and Lithospermum officinale may potentially inhibit the level of thyroid-stimulating hormone (TSH), resulting in decreased levels of thyroid hormone. (Auf'mkolk 1985)(Kaplan 2021)(Santini 2003)(Sourgens 1982)(Sourgens 1986) Additionally, an in vivo animal study showed that oral Lycopus extract may alter peripheral conversion of T4 to T3. (Kaplan 2021) In fact, some evidence suggests that these herbs may be useful as a treatment in cases of hyperthyroidism, as they can lead to restoration of euthyroidism. (Auf'mkolk 1985)(Kawara 2024)(Yarnell 2006) Though this evidence might be useful to consider in the assessment of thyroid function, it’s important to note that more studies are needed to determine clinical relevance.

Labs

Thyroid lab tests can help identify various thyroid disorders, including primary and autoimmune hypothyroidism. Primary hypothyroidism and Hashimoto’s have similar lab findings, with the differentiating feature being the presence of antibodies. 

Recommended initial tests 

(Gaitonde 2012)(Paoletti 2008)

Advanced lab tests

Advanced lab tests can help investigate potential contributing factors to thyroid dysfunction, as thyroid health is influenced by various factors such as diet, stress levels, and environmental toxins. Understanding these factors can provide insights into the root causes of thyroid imbalances, leading to more targeted and effective treatment approaches.

Digestive function and stool analysis 

The gut microbiome plays a role in influencing thyroid health through various mechanisms. Given the gut-thyroid relationship, analysis of the gut flora through microbiome testing can help identify potential microbial imbalances that may be contributing to or exacerbating symptoms of hypothyroidism. Microbiome testing may be particularly useful in autoimmune hypothyroidism as the gut microbiome is involved in immune regulation and therefore could contribute to the development of autoimmune diseases like Hashimoto’s thyroiditis. (Knezevic 2020) It can also help identify specific bacterial imbalances that may be associated with cross-immune responses targeting the thyroid gland. (Bassi 2010)(Kiseleva 2011)(Wang 2010)

Since lifestyle and dietary factors can have an impact on both primary and autoimmune hypothyroidism, advanced lab testing can help provide a comprehensive assessment of these potential contributing factors.

Nutrient deficiencies 

Nutrients play a crucial role in supporting thyroid function. Nutrients like iodine and iron are important for the synthesis of thyroid hormones, while others such as selenium, zinc, and vitamin D are needed for peripheral conversion. (Leko 2023)(Mezzomo 2016)(Polak 2013)(Zimmerman 2002) Additionally, vitamin D and selenium have been shown to decrease anti-TPO antibodies in Hashimoto’s thyroiditis. (de Farias 2015)(Mazokopakis 2015) Therefore, ensuring adequate levels of these nutrients is particularly important in autoimmune thyroid conditions. 

While nutritional intake can be analyzed using dietary recall or a food diary, laboratory assessment can help provide further insights into possible nutritional deficiencies. Lab tests that can help determine potential contributing factors include vitamin D, iron, selenium, and zinc, which are crucial for maintaining healthy thyroid function. Furthermore, advanced nutritional panels such as organic acid testing can be used to evaluate various metabolic markers that can provide insight not only into functional nutrient deficiencies but also other processes such as mitochondrial function which is also impacted in Hashimoto’s thyroiditis. (Esfahanian 2021) (Rogers 2006)

Environmental and toxin panels

Testing for environmental toxins is increasingly recognized as important in the comprehensive management of hypothyroidism. This information can guide healthcare providers in developing targeted treatment strategies that help mitigate ongoing exposure to harmful substances. By reducing or eliminating exposure to environmental toxins through lifestyle modifications, clinicians can support thyroid health and improve overall treatment outcomes for patients with hypothyroidism.

Stress hormones 

Stress can intricately impact thyroid function through several mechanisms. When the body experiences stress, the hypothalamic-pituitary-adrenal (HPA) axis is activated, leading to increased cortisol production. Increased cortisol can suppress the hypothalamic-pituitary-thyroid (HPT) axis, reducing the release of TSH from the pituitary gland. (Cai 2020)(Wondisford 2015) Additionally, stress can hinder the conversion of T4 to T3, further impairing thyroid function. (Holtorf 2014) Chronic stress also contributes to immune dysregulation, potentially triggering or worsening autoimmune thyroid conditions like Hashimoto's thyroiditis or Graves' disease. (Mizokami 2004)(Puttaswamy 2024) Managing stress is crucial for maintaining optimal thyroid hormone production and regulation in the body. 

The bottom line

A comprehensive assessment for hypothyroidism is crucial for accurate diagnosis and effective treatment planning. Beyond simple laboratory tests, such an assessment considers a range of factors that may be contributing to a patient’s condition. This holistic approach helps to identify underlying causes such as autoimmune disorders (like Hashimoto's thyroiditis), nutrient deficiencies, medications, or previous treatments that may contribute to thyroid dysfunction. It also ensures that individual patient needs are addressed, facilitating personalized treatment strategies that optimize thyroid hormone levels and improve overall well-being. 

By conducting a thorough assessment, healthcare providers can tailor interventions that not only alleviate symptoms but also address any underlying etiology, thereby enhancing the quality of life for individuals with hypothyroidism.