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Lithium is a well-known treatment option for bipolar disorder and depression that can alter thyroid function even without a history of thyroid disease. However, this medication is critical in managing bipolar disorder. Therefore, if you need to take lithium, you need to know what signs may indicate thyroid dysfunction.
Lithium is an element found in almost all rocks. Despite the extensive research on this medication, we know little about how it works to treat psychiatric conditions. One of the leading theories is that it stimulates chemical messengers in the brain that regulate your mood, thought patterns, and behavior.
People taking lithium need to take it every day as prescribed by their doctor. It is not safe to stop taking it without consulting your doctor first. People who do stop taking it are at risk of having mood symptoms reoccur.
Like any medication, there are side effects to taking lithium, including:
- Nausea and vomiting
- Increased urination
- Appetite changes and increased thirst
- Dry mouth
- Hair loss
More severe side effects include lithium toxicity and diabetes insipidus, an uncommon disorder that causes an imbalance of fluids in the body. Women who wish to become pregnant also need to talk with their doctor before conceiving, as lithium may cause heart defects in babies.
Long term risks
Lithium is often a lifelong medication. Thus, some conditions can arise with long-term use, like kidney problems. To watch for kidney dysfunction, people need to have routine kidney function tests.
Lithium may inhibit iodine uptake by the thyroid gland. Iodine is an element that essential to the production of thyroid hormone. Lithium also inhibits iodotyrosine coupling (a reaction in the formation of thyroid hormone) and thyroid hormone secretion. This impact on thyroid hormone secretion may lead to the development of hypothyroidism and goiter.
An estimated 40 percent of people taking lithium develop a goiter, an enlarged, swollen thyroid gland. Goiters often appear in the first two years of taking lithium. Likely, people get goiters because lithium increases thyroid-stimulating hormone (TSH) concentration in the body, resulting in thyroid gland enlargement. Another theory suggests that lithium activates tyrosine kinase, which stimulates thyroid cells to grow and multiply.
Sometimes, a goiter requires removal if it becomes too large, especially if it starts to affect your ability to breathe.
About 20% of people taking lithium develop hypothyroidism. Most people will have subclinical hypothyroidism, which is where TSH levels are slightly elevated, but T4 and T3 levels are normal. However, some people will develop overt or primary hypothyroidism.
Lithium may increase autoimmunity, which is where your immune system attacks your healthy cells. Specifically related to thyroid, Hashimoto's thyroiditis is an autoimmune condition in which the immune system attacks the thyroid gland. Hashimoto's is one of the leading causes of hypothyroidism. This autoimmune condition tends to run in families, and women are more likely to be affected. A family history of any autoimmune disease can increase your risk for developing hypothyroidism, especially when taking lithium.
Although less common than developing a goiter or hypothyroidism, an overactive thyroid may also be a risk factor in lithium therapy. We still don’t know precisely why hyperthyroidism may develop in this case. Lithium may have a direct toxic effect on the thyroid gland. Additionally, it may be related to autoimmunity as well.
Your thyroid is one of the main organs your doctor will assess before starting lithium therapy. Checking your thyroid is essential because people who have thyroid disease before starting lithium are at greater risk for their condition worsening.
Your doctor will start by doing a physical exam to look for signs of thyroid disease, including:
- Under or overactive reflexes
- Swelling, nodules, or irregularity in your thyroid gland
- Checking your vitals, especially your heart rate, rhythm, and blood pressure
- Examining your eyes for exophthalmos (bulging eyes) or dryness
- Assessing your weight
- Observing your skin and hair distribution
While physical signs and symptoms are important markers for determining thyroid health, a thyroid blood test provides a more accurate window into what is going on in the body. A thyroid function test usually assesses TSH, Free T4, Free T3, and TPO antibodies.
You should regularly check your thyroid function when taking lithium, as thyroid disease can develop anytime after starting the medication.
Yes. It is vital for people who need lithium to take it, even if they have a thyroid condition. While there are risks with taking lithium, the benefits often outweigh these risks. Often, people who take lithium struggle with manic depression, which may lead to suicidal thoughts and ideation. If you do not take lithium, it could potentially result in death.
It is, however, necessary to see your doctor regularly to check your thyroid function (along with your kidneys and overall health). If you start to develop new or worsening symptoms, it is essential to notify your doctor immediately.
A note from Paloma
Lithium-induced thyroid dysfunction can be managed and treated. Meet with a trusted thyroid doctor to learn about your options for keeping your thyroid happy and healthy.