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Lithium and Thyroid Disease

The Thyroid Impact of Lithium Treatment for Bipolar Disease

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Updated June 10, 2014

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Patients with bipolar disorder are often surprised to learn that thyroid problems are a common side effect of the drug lithium, which is a common treatment for bipolar disorder, also known as manic depression.

Experts don't understand the exact mechanism, but the drug lithium can prevent your thyroid from functioning properly. Lithium is known to cause goiter (an enlarged thyroid), as well as hypothyroidism, and chronic autoimmune thyroiditis. There is also a link to hyperthyroidism in some patients.

Goiter is the most common thyroid-related side effect of lithium, and is through to occur in approximately half of all patients treated with lithium. Goiter usually develops within the first two years of treatment. With a lithium-induced goiter, your thyroid can enlarge to as much as twice its normal size.

Hypothyroidism -- a deficiency in thyroid hormone -- is estimated to occur in 20 to 30 % of patients taking lithium. It most often occurs during the first two years of lithium treatment. Women over 45 are at greater risk of lithium-induced hypothyroidism, and the overall risk of hypothyroidism increases with age.

The hypothyroidism can be subclinical -- with an elevated TSH level, and normal T4 and T3 -- with few signs or symptoms. A small percentage of patients, however, develop overt hypothyroidism, with its typical signs and symptoms. These patients should be treated for the hypothyroidism.

Patients taking lithium are also at risk of developing chronic autoimmune thyroiditis -- an autoimmune inflammation of the thyroid gland. For patients who are just starting lithium therapy, the presence of antithyroid antibodies -- even without active thyroid dysfunction -- puts them at higher risk of developing an overt thyroid condition while being treated with lithium. There also appears to be some evidence that lithium itself can cause elevated antibodies and the onset of autoimmune thyroid disease in some patients.

Lithium treatment also appears to be linked to an increased risk of hyperthyroidism -- an excess of thyroid hormone. Several studies have shown that hyperthyroidism is two to three times more prevalent in patients treated with lithium, versus in the general population.

What Should Patients Do? Advice from UpToDate 

In order to help patients taking lithium understand more about the thyroid-related effects, I looked up what the experts say in UpToDate -- a trusted electronic reference that is used by many physicians:
Because of the high incidence of goiter and hypothyroidism that occurs during lithium treatment, patients should have a careful thyroid physical examination and determination of serum TSH and antithyroid antibody titers before lithium treatment is begun. Patients with normal thyroid function at that time should be reevaluated every six to 12 months for several years. If thyroid function is abnormal at the initial evaluation, lithium can still be given if necessary but the thyroid dysfunction should be treated.
What this means is that if you are prescribed lithium, you'll need to make sure that you have a thorough clinical thyroid examination -- as well as blood tests to measure TSH and antithyroid antibody levels, before you start your lithium therapy. As long as you are taking lithium, your doctor should reevaluate your thyroid function, including blood tests, every six to 12 months.

If you develop a thyroid problem while on lithium, your lithium does not need to be discontinued, as long as you are getting effective therapy for your thyroid condition. Your physician will need to monitor your thyroid and the response to treatment, to determine if continuing with lithium is the best option for your health.

Want to learn more? See UpToDate's topic, "Lithium and the thyroid," for additional in-depth, current and unbiased medical information on name the condition/disease of relevance, including expert physician recommendations.

Source:

Surks, Martin. "Lithium and the thyroid." UpToDate.  Accessed: March 2009.

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