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On average, more than 21% of Americans have used unprescribed or illegal drugs – sometimes referred to as “recreational” drugs – in the last year. Drug use is also on the rise in the U.S.
What does this have to do with the thyroid? A great deal, actually. Our bodies regulate hormones through complex pathways. A change, even a small one, can have significant repercussions throughout the body. Using unprescribed and recreational drugs can alter how the body regulates hormones, ultimately affecting how the body functions.
Ahead, a look at the effects of opioids, cocaine, and cannabis on thyroid function.
You need to know a bit about how endocrine glands work to understand the effect of drugs on your thyroid. Your glands produce chemical messengers called hormones. These messengers affect many processes in our bodies, including the following:
- Growth and development
- Sexual function
Your hypothalamus, located in your brain, releases thyrotropin-releasing hormone (TRH). TRH tells the pituitary gland to release thyroid stimulating hormone (TSH). This release of TSH signals the thyroid gland to release thyroid hormones, namely thyroxine (T4) and triiodothyronine (T3).
Once released, T3 and T4 travel through your bloodstream, either bound to a thyroid-binding protein (TBG) or unbound (free). Free T3 and T4 enter tissue cells where the conversion of T4 to the active thyroid hormone T3 takes place.
As more T4 converts to T3, your T4 levels drop. Because of this, your hypothalamus releases TRH, signaling the release of TSH. And the cycle repeats.
This cycle is called the hypothalamus-pituitary-thyroid (HPT) axis. A disruption anywhere in this cycle can lead to thyroid disease and dysfunction, such as:
- Hyperthyroidism: an overactive thyroid gland producing too much thyroid hormone
- Hypothyroidism: an underactive thyroid gland producing too little thyroid hormone
Next, let’s look at how drug use can disrupt the HPT axis.
Healthcare providers prescribe opioids such as morphine, fentanyl, and oxycodone to help relieve pain. Morphine – and the street drugs heroin and opium – are both derived from the opium poppy plant. The alterations of thyroid function differ depending on the specific opioid taken.
A 2014 study showed that opium increases the concentration of TBG in your body. TBG binds to thyroid hormones, making them inactive. As TBG levels increase, thyroid hormone metabolism decreases. Because of this, total (bound plus unbound) T3 increases, and free T4 levels lower. A low T4 level would stimulate the start of the HPT axis.
Although morphine comes from opium, it appears to affect thyroid function differently. But, morphine’s exact effect on thyroid function isn’t clearly understood. The 2014 study mentioned above suggests that morphine may decrease TSH alone or decrease TSH, T4, and T3 levels. But, a 2020 study showed the opposite, stating that morphine administration (acute or chronic) might increase TSH levels.
More research is needed to expand the understanding of which opioids are more likely to affect glands and hormones, including the thyroid. It’s also not known how long it takes for opioid use to affect thyroid function or if stopping opioids will restore thyroid function to normal.
Some research suggests that cocaine abuse stimulates the production of TRH. At the same time, your pituitary gland will have a reduced response to TRH. Because of this, lower amounts of TSH are released, resulting in low TSH levels and, in some cases, hyperthyroidism.
A 2014 case report attributed a case of thyroid storm, a life-threatening medical condition due to undiagnosed hyperthyroidism, to cocaine abuse. This patient presented with a low TSH level and high free T4 and T3 levels.
Animal studies, however, have found that acute or chronic cocaine abuse doesn’t affect thyroid hormone levels.
With the legalization of medical and recreational marijuana in a number of states, the use – and abuse – of this drug is on the rise.
A 2017 study found that “recent marijuana users had significantly lower frequency of elevated TSH and positive anti-thyroperoxidase antibody (TPOAb) versus nonusers/past users.”
Recent studies also suggest that marijuana use may suppress TSH at the hypothalamic level.
A 2022 study found that cannabis and related cannabinoids – such as generally legalized Delta-9 products – can impact thyroid, adrenal, and sex hormone function, including “lower thyroid hormone levels with acute use” and adverse effects on the adrenals and stress response, blood sugar, and fertility.
Currently, there are no controlled studies on the effect of marijuana use on thyroid function in humans. More investigation is needed to establish whether occasional or chronic use of cannabis products directly impacts thyroid function.
Depending on the drug and whether it’s used occasionally or chronically abused, there’s a potential for changes in thyroid function due to disruption of the HPT axis. How the thyroid will specifically be affected, and to what extent, is still a topic of debate.
As a patient, one thing you can do is be open and honest with your health care provider about the use or abuse of any drugs, including legal cannabis or Delta-9 products. If you regularly use or abuse illegal or prescription drugs, you should also ensure that you periodically check your thyroid levels to monitor for any changes. Our Paloma comprehensive home Thyroid Test Kit makes it easy and affordable to get blood tests that accurately measure your TSH, Free T4, Free T3, and TPOAb at home.
Finally, if you or someone you know is struggling with a substance abuse disorder, call 1-800-662-HELP or visit SAMHSA’s confidential services locator for information on treatment centers and additional resources.