Lithium-Induced Hypothyroidism

What is Lithium-Induced Hypothyroidism?

Lithium-induced hypothyroidism is a condition where the thyroid gland produces too little thyroid hormone as a side effect of lithium medication. Lithium is commonly prescribed to treat bipolar disorder and certain mood disorders. While it can be highly effective for mental health, it can interfere with how your thyroid works.

The thyroid is a small gland in your neck that makes hormones to control your metabolism, energy levels, and body temperature. Lithium can block the release of thyroid hormone and may cause the thyroid to grow larger. This side effect develops in about 15 to 20 percent of people taking lithium long-term.

The good news is that lithium-induced hypothyroidism can be detected early with regular blood testing. Most people can continue their lithium therapy while treating the thyroid condition separately. Catching it early helps prevent symptoms and complications from developing.

Thyroxine Free (FT4), Immunoassay

Pinpoint the cause of your fatigue
Reveal hidden thyroid issues effortlessly
Clarify why you're gaining weight

^$99

Thyroid TSH w/ Free T4 & Free T3

Pinpoint the cause of your fatigue
Reveal hidden thyroid issues effortlessly
Clarify why you're struggling with weight

^$100

Complete Thyroid Follow up

Pinpoint the cause of your fatigue
Reveal underlying thyroid issues effortlessly
Clarify the reason behind weight changes

^$133

Symptoms

Many people with lithium-induced hypothyroidism experience:

Fatigue and low energy levels
Weight gain despite no changes in diet
Feeling cold more easily than usual
Dry skin and brittle hair
Constipation
Difficulty concentrating or brain fog
Depression or worsening mood symptoms
Slowed heart rate
Muscle weakness or aches
Swelling in the neck from an enlarged thyroid

Some people have no noticeable symptoms in the early stages. This is why regular thyroid monitoring is essential for anyone taking lithium medication.

Causes and risk factors

Lithium medication is the direct cause of this condition. Lithium interferes with several steps in thyroid hormone production and release. It blocks the thyroid gland from releasing hormones into your bloodstream. It can also prevent your thyroid from taking up iodine, which is needed to make thyroid hormone. In some cases, lithium triggers an autoimmune response where your body attacks the thyroid gland.

Your risk is higher if you take lithium for many years, have a family history of thyroid problems, or are female. Women are 2 to 3 times more likely to develop this condition than men. People who already have thyroid antibodies before starting lithium face increased risk. Higher doses of lithium and older age also increase the likelihood of developing hypothyroidism.

How it's diagnosed

Lithium-induced hypothyroidism is diagnosed through blood tests that measure thyroid function. The most important tests are Free Thyroxine, also known as FT4, and Thyroid Stimulating Hormone, or TSH. Low FT4 combined with high TSH indicates that your thyroid is underactive. Your doctor will compare these results to your baseline thyroid function from before you started lithium.

Regular monitoring is critical for anyone on lithium therapy. Most guidelines recommend checking thyroid function every 6 to 12 months during treatment. Rite Aid offers comprehensive thyroid testing including Free Thyroxine (FT4) through our preventive health panel. Early detection allows for treatment before symptoms affect your quality of life.

Treatment options

Continue lithium therapy while treating the thyroid condition separately in most cases
Start thyroid hormone replacement medication such as levothyroxine
Monitor thyroid levels every 6 to 8 weeks when starting treatment, then every 6 to 12 months once stable
Ensure adequate iodine intake through diet, including iodized salt, seafood, and dairy products
Eat selenium-rich foods like Brazil nuts, fish, and eggs to support thyroid function
Avoid excessive consumption of raw cruciferous vegetables that can interfere with thyroid hormone production
Work closely with both your psychiatrist and primary care doctor to balance mental health and thyroid treatment
In rare cases, switch to a different mood stabilizer if thyroid problems cannot be managed
Maintain consistent timing of thyroid medication, typically taken on an empty stomach in the morning

Frequently asked questions

Yes, most people can safely continue lithium therapy while treating hypothyroidism. Your doctor will typically prescribe thyroid hormone replacement medication like levothyroxine. This allows you to maintain the mental health benefits of lithium while correcting your thyroid hormone levels. Regular monitoring ensures both medications are working properly.

Lithium-induced hypothyroidism can develop at any time during treatment, but it most commonly appears within the first 2 years. Some people develop it within months, while others may take 10 or more years. The risk continues as long as you take lithium. This is why ongoing thyroid monitoring is essential throughout your treatment.

The primary tests are Free Thyroxine, or FT4, and Thyroid Stimulating Hormone, or TSH. Low FT4 with high TSH indicates hypothyroidism. Your doctor may also check thyroid antibodies to determine if an autoimmune process is involved. Baseline thyroid testing before starting lithium helps track any changes over time.

Most experts recommend thyroid testing every 6 to 12 months during lithium therapy. Your doctor may test more frequently if you have risk factors or develop symptoms. Testing should occur before you start lithium to establish a baseline. More frequent monitoring is needed when starting thyroid hormone replacement.

Sometimes, but not always. Some people see their thyroid function return to normal after discontinuing lithium. However, many continue to need thyroid hormone replacement even after stopping the medication. The likelihood of reversal depends on how long you took lithium and the severity of thyroid damage. Never stop lithium without medical supervision.

Common symptoms include fatigue, weight gain, feeling cold, dry skin, constipation, and difficulty concentrating. Some people notice depression or worsening mood symptoms. You might experience muscle aches, slowed heart rate, or swelling in your neck. Many people have no symptoms early on, which is why regular blood testing is critical.

No, only about 15 to 20 percent of people taking lithium long-term develop hypothyroidism. Women face higher risk than men. People with a family history of thyroid disease or existing thyroid antibodies are more likely to be affected. Regular monitoring helps catch the condition early in those who do develop it.

While diet cannot prevent the condition entirely, adequate iodine and selenium intake support healthy thyroid function. Include iodized salt, seafood, dairy, Brazil nuts, and eggs in your diet. However, these dietary measures cannot overcome the direct effects of lithium on the thyroid. Regular blood testing remains the most important prevention strategy.

Treatment typically involves taking thyroid hormone replacement medication, usually levothyroxine, while continuing lithium. Your doctor will adjust the dose based on regular blood tests. Most people respond well to this approach. Lifestyle factors like adequate iodine intake and stress management can support treatment.

It can be, but not always. Some people need lifelong thyroid hormone replacement, while others recover after stopping lithium. The duration of lithium use and degree of thyroid damage influence whether the condition is permanent. Even if permanent, hypothyroidism is highly manageable with daily medication and regular monitoring.