Quick Answer
Thyroid monitoring on lithium is part of safe bipolar care. The FDA label calls for thyroid testing before starting lithium and regular monitoring afterward, since lithium can cause hypothyroidism or, less often, hyperthyroidism. Low thyroid function can cause fatigue, low mood and weight gain that look like bipolar depression. Treatment is usually simple.
Understanding thyroid Monitoring on Lithium
The thyroid gland helps regulate energy, metabolism, temperature and mood. Lithium can affect how the thyroid works, and over time some people taking lithium develop hypothyroidism, an underactive thyroid. Less often, lithium can be linked with an overactive thyroid. The FDA prescribing information for lithium includes hypothyroidism and hyperthyroidism among its warnings and calls for thyroid function to be evaluated before starting treatment and monitored regularly afterward. Regular blood tests, usually including TSH, help catch changes early, often before symptoms appear. This guide is part of Dr. Farkas's New York bipolar resources.
Thyroid changes matter in bipolar disorder because low thyroid function can look like bipolar depression. Fatigue, low mood, slowed thinking, weight gain, feeling cold and dry skin can all come from an underactive thyroid. Untreated hypothyroidism may also make bipolar depression harder to treat. That’s why a check of thyroid function is part of evaluating any depressive episode in someone taking lithium. Our guide on starting lithium explains the full set of baseline and ongoing tests.
For New Yorkers on lithium for years, a routine thyroid check can explain fatigue that might otherwise be blamed on depression. The NYC Health Department noted that among adults in serious distress who didn’t get care they wanted, not knowing where to go and cost were common barriers. Secure video visits from anywhere in New York can make it easier to start bipolar care and keep regular follow-ups without extra travel.
How lithium affects the thyroid, thyroid symptoms vs. depression, and treating thyroid changes are the three topics this guide covers.
Thyroid and mood beyond lithium
Thyroid problems can occur in anyone, with or without lithium, and they can affect mood. Some people with bipolar disorder who aren’t on lithium are still checked for thyroid function, especially during depression or rapid mood changes. Thyroid conditions are common, particularly in women, so periodic checks are a sensible part of bipolar care.
Coordinating care
If you see a primary care doctor or endocrinologist, sharing thyroid results and medication changes keeps care aligned. Thyroid medication doses may need adjustment over time. Taking thyroid medication consistently, usually on an empty stomach, helps keep levels steady. Your care team can coordinate the details.
Thyroid Monitoring on Lithium at a glance
| Symptom | Low thyroid | Bipolar depression |
|---|---|---|
| Fatigue | Common | Common |
| Low mood | Can occur | Core symptom |
| Weight gain | Common | Can occur |
| Feeling cold, dry skin | Common | Less typical |
| Blood test | Shows thyroid change | Thyroid normal |
Testing schedule
Thyroid tests are usually done before lithium starts, again within the first several months and then periodically, often every six to twelve months once stable, or more often if symptoms or risk factors appear. Women, people with a family history of thyroid disease and those with thyroid antibodies may be at higher risk. Your clinician will set a schedule that fits you. Keeping copies of results helps you see trends.
Treating thyroid changes
If lithium lowers thyroid function, treatment is usually straightforward: thyroid hormone replacement, often levothyroxine, prescribed by your psychiatric clinician, primary care doctor or an endocrinologist. Many people continue lithium successfully while taking thyroid medication. Stopping lithium isn’t usually necessary just because of thyroid changes, and stopping suddenly can trigger relapse. Decisions are made together based on the full picture. Our guides on starting lithium and bipolar depression with kidney disease cover related topics.
Lithium thyroid care for New York patients
Thyroid results can be reviewed during secure video visits, with labs drawn locally. Visits run by secure video anywhere in New York, while you’re physically in the state. The practice is in-network with Aetna and Cigna; confirm your New York plan with the office, and see self-pay fees on the Good Faith Estimate page.
Other lithium monitoring
Thyroid checks are one part of lithium monitoring. Kidney function, electrolytes, calcium and lithium levels are also checked regularly. Together, these tests help keep lithium safe for long-term use. Many people take lithium for years with careful monitoring and good results.
When to seek help
Tell your clinician if you notice new fatigue, weight gain, feeling cold, dry skin, constipation or low mood while taking lithium. Seek urgent care for signs of lithium toxicity. Thoughts of suicide need immediate help through 988. Thyroid changes on lithium are common and treatable.
Some people notice their energy and mood improve noticeably once a thyroid problem is treated, which can make it seem as if depression lifted on its own. Tracking mood alongside thyroid results helps sort out what changed. If depression continues after thyroid levels are back in range, bipolar treatment itself may need adjustment. Keeping both pieces in view prevents confusion and helps your clinician make clear, targeted changes.
Key Takeaways
- Lithium can lower thyroid function over time.
- Hypothyroidism can mimic or worsen bipolar depression.
- The FDA label calls for regular thyroid monitoring on lithium.
- Thyroid changes are usually treatable without stopping lithium.
The Bottom Line
Thyroid Monitoring on Lithium is common and treatable, and careful care can make daily life feel more manageable.
Frequently Asked Questions
Can lithium affect the thyroid?
Yes, lithium can lower thyroid function over time, causing hypothyroidism. Less often, it can be linked with an overactive thyroid. The FDA label includes both among its warnings. Regular blood tests catch changes early. Most thyroid changes are treatable. An evaluation can clarify what's happening and which options fit.
Can low thyroid look like bipolar depression?
Yes, an underactive thyroid can cause fatigue, low mood, slowed thinking and weight gain. These overlap with bipolar depression. Untreated hypothyroidism may make depression harder to treat. Thyroid testing is part of evaluating depression on lithium. A blood test can tell the difference. An evaluation can clarify what's happening and which options fit.
How often should thyroid be checked on lithium?
Thyroid tests are usually done before lithium starts and again within the first several months. Once stable, they're often repeated every six to twelve months. People with risk factors may need more frequent checks. Your clinician sets the schedule. Keeping copies of results helps track trends.
Do I have to stop lithium if my thyroid changes?
Not usually for most people. Thyroid changes on lithium are often treated with thyroid hormone replacement, like levothyroxine. Many people continue lithium successfully. Stopping lithium suddenly can trigger relapse. Decisions are made together based on the full picture. An evaluation can clarify what's happening and which options fit.
Who treats thyroid problems from lithium?
Your psychiatric clinician, primary care doctor or an endocrinologist may treat thyroid changes. Sharing results keeps care aligned. Thyroid medication doses may need adjustment over time. Taking it consistently helps keep levels steady. Your care team can coordinate. An evaluation can clarify what's happening and which options fit.
Can thyroid monitoring on lithium happen through telehealth in New York?
Yes, thyroid results are reviewed during secure video visits anywhere in New York, with labs drawn at a lab near you. You need to be physically in New York during each visit. Lab orders are sent electronically. The practice is in-network with Aetna and Cigna; confirm your New York plan with the office. Prescriptions go electronically to your pharmacy.
Where to go from here
- Right now, if you're not safe
- Call or text 988, or call 911.
- If you'd like an evaluation
- See how scheduling and telehealth work on the new patient page.
- If you want to keep reading
- Return to our full set of New York bipolar depression guides for more guides. For more help preparing and finding care, see NIMH’s tips for talking with your health care provider.
How We Reviewed This Page
Written by Steven Lockhart of Health Marketing Group and clinically reviewed by Gabriella I. Farkas, MD PhD, a board-certified psychiatrist. Clinical information comes from the sources listed below, and the page is reviewed every 180 days or when guidance changes.
What’s new: September 29, 2026. Page published.
References
- FDA. Lithium and Lithium Carbonate Prescribing Information (2018). https://www.accessdata.fda.gov/drugsatfda_docs/label/2018/017812s033,018421s032,018558s027lbl.pdf
- National Institute of Mental Health. Understanding the Link Between Chronic Disease and Depression. https://www.nimh.nih.gov/health/publications/chronic-illness-mental-health
- NYC Health Department. The State of Mental Health of New Yorkers (2024). https://www.nyc.gov/assets/doh/downloads/pdf/mh/state-of-mental-health-new-yorkers.pdf
- 988 Suicide & Crisis Lifeline. https://988lifeline.org/
- Tips for talking with your health care provider. https://www.nimh.nih.gov/health/publications/tips-for-talking-with-your-health-care-provider