Cannabis & Thyroid Health

Providers caring for patients with thyroid disorders know how difficult it can be to get symptoms under control, even with conventional treatment options. Plagued by fatigue, anxiety, depression, memory problems, weight gain, and more, patients with thyroid disorders often struggle to find relief from these all-too-common symptoms, leading to a decreased quality of life.

While there’s a lack of clinical evidence to support cannabinoid therapy as a tool to help improve or cure thyroid disorders, there’s evidence that chronic cannabis consumption doesn’t have a negative influence on thyroid function in humans.1 Furthermore, there are data to support the value of using cannabis to manage autoimmune conditions, the category under which the most common thyroid disorders—Hashimoto’s thyroiditis and Graves’ disease—fall.2

While there isn’t enough research to support the role between cannabis consumption and reversal of thyroid disease, anecdotal reports from patients suggest cannabis can be an effective solution for managing the condition’s symptoms.

Thyroid Disease Overview
The thyroid is a hormone-producing gland located at the base of the neck. While this butterfly-shaped gland is small, it affects every cell, tissue, organ, and function of the body. When healthy, the thyroid secretes hormones that affect critically important functions of the body, including physical growth, brain development, metabolism, and body temperature regulation.

But when unhealthy, the thyroid doesn’t produce adequate hormones for the body to function properly, leading to a vast array of unpleasant symptoms including weight gain, joint pain, muscle pain, thinning hair, and an unusual sensitivity to cold. Other symptoms, such as excessive fatigue, sleep problems, anxiety, and depression, can take a particularly severe toll on patients’ quality of life. It’s believed that common lifestyle factors such as extreme stress, environmental toxins, a sedentary lifestyle, and poor dietary choices all play an important role in the development of thyroid disease.

According to the American Thyroid Association, an estimated 20 million Americans live with some form of thyroid disease, with women being five to eight times more likely to be affected than men; more than 12% of the US population will develop a thyroid disorder in their lifetime.3 The most prevalent type of thyroid condition is hypothyroidism, the most common cause of which is the autoimmune condition Hashimoto’s thyroiditis.4 Other common thyroid disorders include hyperthyroidism, Graves’ disease, goiter, and thyroid cancer. Undiagnosed or untreated, thyroid disease can wreak havoc, producing debilitating symptoms that may put patients at risk for more long-term chronic health conditions such as cardiovascular disease.

Limited Available Clinical Evidence
Preliminary evidence suggests that cannabis consumption doesn’t play a role in the development of thyroid disease.1 Unfortunately, there remains a significant lack of concrete scientific evidence to support the use of cannabis in the treatment of thyroid disorders. The available scientific studies are limited by small sample sizes and a lack of human participants. For this reason, it’s essential that cannabis professionals advocate for the removal of cannabis from the Federal Schedule I drug classification to allow for more scientific studies to be done to increase understanding the role of cannabis in thyroid function. In the absence of substantial clinical evidence to guide cannabis use for the treatment of thyroid disorders, what’s left is to examine the role between autoimmunity and the role and function of the endocannabinoid system (ECS).

Autoimmunity and the ECS
An autoimmune thyroid disease such as Hashimoto’s thyroiditis is sparked when the immune system mistakenly generates autoantibodies, or antibodies that fight self-antigens, which are healthy cells and tissues of the body, resulting in damage. The immune system misidentifies the self-antigens as foreign bodies, causing the immune system to attack otherwise healthy cells; this can, over time, lead to autoimmune disease.

In the case of Hashimoto’s, the body misidentifies the cells that produce thyroid hormones as foreign invaders, causing an immune response that interferes with the thyroid’s function and hormone production, ultimately leading to the development of hypothyroidism. In the case of Graves’ disease, the opposite is true; the immune system creates antibodies that cause the thyroid to make more hormones than are needed and causes the thyroid gland to enlarge.4,5 Other autoimmune-induced thyroid disorders include postpartum thyroiditis and subacute thyroiditis.

The ECS is an important modulator of the immune system and can be influenced by a patient’s cannabis use, making it an important factor to consider when managing autoimmune thyroid conditions.

The ECS, which has a broad purpose of maintaining homeostasis within the body, is made up of three major components: messengers, receptors, and enzymes. There are two primary cannabinoid receptors, CB1 receptors, found in the brain and central nervous system, and CB2 receptors, found primarily on immune cells. Evidence supports the immune-modulating effects of cannabis and its active ingredients, which affect T-cells, B-cells, monocytes, and microglia cells, resulting in decreased expression of proinflammatory cytokines and increased anti-inflammatory cytokines.6,7

In the ECS, the majority of CB2 receptors are located in the immune system, suggesting that cannabinoids may play an important role in modulating the immune response associated with Hashimoto’s or Graves’ disease. When exogenous cannabinoids such as CBD or THC are introduced to the body through cannabis use, they exert an autoimmune effect by modulating neurotransmitter and cytokine release while possessing immunosuppressive properties through apoptosis.6,7

Various tissues in the body, including the thyroid gland, can contain CB1 and/or CB2 cannabinoid receptors, although each receptor is believed to be linked to a different action. CB2 receptors are found mostly in the peripheral tissues of the body, including the immune system. It’s believed that CB2 receptors are mediators for suppressing pain and inflammation and have therapeutic potential in inflammatory, fibrotic, and neurodegenerative diseases.8

While the relationship between CB2 receptors and the immune system has yet to be fully defined, CB2 receptors activate the immunomodulatory effects of endocannabinoids and signal the immune system as needed. This makes them of particular interest for the development of a therapeutic treatment for autoimmune-related thyroid conditions due to their location, their mode of action, and their inability to cause intoxicating effects, unlike CB1 receptors.9

There have been limited explicit connections made between the ECS and the thyroid gland, but there’s some research published in the journal Endokrynologia Polska that examines the effects of cannabinoids on the endocrine system. Researchers note that endocannabinoids have been shown to help moderate food intake and the body’s energy homeostasis, as well as significantly affect the endocrine system and the activity of the pituitary gland, adrenal cortex, thyroid gland, pancreas, and gonads.10

Cannabis Consumption and the Development of Thyroid Disease
With limited evidence available, it’s important to note that preliminary studies have suggested that cannabis consumption isn’t directly tied to—nor is it known to be a risk fact for—thyroid disorder development, and chronic consumption doesn’t significantly influence thyroid function.1

According to the Handbook of Cannabis and Related Pathologies, as of 2017 there were only four published studies that examined the effects of cannabis on human thyroid function. A review of these studies observed that regular cannabis consumption, particularly of THC, was associated with only minor effects on thyroid function tests in serum. Overall, it was noted that chronic cannabis smokers, when compared with nonsmoking controls, had stable thyroid-stimulating hormone (TSH) levels, while total T4 and total T3 levels were found to be lower but still within normal limits. No thyroid function tests were significantly influenced by serum levels of THC.1

These findings build upon a 2013 study published in Pharmacopsychiatry that evaluated the thyroid function tests (TSH, total T3, and free T4) of 39 cannabis-dependent subjects. All participants showed levels of TSH, total T3, and free T4 within a typical range, and thyroid hormones levels weren’t significantly associated with serum levels of THC, 11-hydroxy-THC, or 11-nor-9-carboxy-THC.1

One study published in the journal Thyroid studied the effect of cannabis use on thyroid function and autoimmunity. In this cross-sectional analysis, data from the National Health and Nutrition Examination Survey 2007–2012 were used to assess the effects of cannabis on thyroid function and autoimmunity in users. Their findings suggest that “recent cannabis use is either protective for subclinical hypothyroidism, or the lower TSH level seen among recent marijuana users may be due to hypothalamic suppression of TSH, as noted in prior animal studies.” The conclusion remained that recent cannabis use wasn’t associated with thyroid dysfunction but was significantly correlated with lower TSH levels. This limited evidence suggests that cannabis consumption may be beneficial for those with hypothyroidism. Hypothyroidism is characterized by high TSH levels, which indicate that the body isn’t making enough thyroid hormones.11

Practical Recommendations for Clinicians
With limited evidence to direct the use of cannabis for the treatment of thyroid conditions, it’s important for clinicians to remember to treat the patient, not the condition. With so many different types of thyroid disorders, it’s imperative that clinicians work with patients to deliver patient-centered care. Additionally, clinicians must remember that no two ECSs can be treated the same. While there are some general guidelines for introducing a patient to cannabis use, it’s crucial to tailor individual recommendations for their unique circumstance.

While it seems simple, this process often requires patience and willingness to experiment to find the ideal application method and dose. Each patient reacts differently to the various combinations and ratios of cannabinoids and terpenes unique to each strain of the plant. Clinical evidence points both to cannabinoids and terpenes as mediators of disease. Many theories suggest that it’s the entourage effect—the potential cannabis synergy and complementary pharmacological activities between phytocannabinoids and terpenoids—that has the greatest likelihood of producing the most significant reduction in systemic pain and other symptoms. For clinicians, this suggests that whole-plant, full-spectrum cannabis products likely will produce the most significant results for patients. This also points to the importance of looking into various terpene profiles and the potential health benefits they may hold. Working with patients to trial various cannabinoid ratios, application methods, and dosages, clinicians can find a solution that provides optimal pain and symptom relief without unwanted side effects.

— Emily Kyle, MS, RDN, CDN, CLT, HCP, is a certified holistic cannabis practitioner.

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