Hyperthyroidism is the medical term doctors use to describe excessive production of hormones in your thyroid gland, a small organ that sits in the lower front region of your neck. You rely on your thyroid hormones for a number of essential body functions, but an overabundance of these substances can significantly harm your health. Current scientific evidence indicates that hyperthyroidism can produce symptoms of mania that are more or less identical to the mania symptoms found in people with the mental health condition called bipolar disorder. In turn, people with bipolar disorder have increased risks for developing hyperthyroidism. Hyperthyroidism Basics The thyroid gland produces hormones, called triiodothyronine (typically abbreviated as T3) and thyroxine (typically abbreviated as T4), which your body needs to maintain functions that include controlling your metabolism, determining how much activity the cells in your organs can sustain, and creating a wide variety of vital proteins. The amount of T3 and T4 your thyroid produces is regulated by a third hormone, called TSH (thyroid-stimulating hormone), produced at the bottom of your brain inside your pituitary gland. In order for you to properly maintain your thyroid-related health, your T3 and T4 levels must stay within a certain range. People develop hyperthyroidism when their thyroid glands produce too much of these hormones. In some cases, this overproduction occurs over a relatively short span of time; in other cases, it occurs over an extended period of time. Apart from any mania-related issues, known effects of hyperthyroidism include an unusual sensitivity to heat, intermittent or absent menstruation, heightened sweat output, concentration problems, jitteriness or nervousness, unexplained weight loss, a form of neck swelling called a goiter, sleeping problems and male breast enlargement. Known hyperthyroidism causes include high consumption of supplemental thyroid hormones, excessive iodine consumption, thyroid gland inflammation, the effects of certain ovarian and testicular tumors, and benign pituitary or thyroid growths. However, most people develop the disorder as a complication of a medical condition called Graves disease. Hyperthyroidism and Bipolar Disorder Mania is a classic symptom of bipolar I disorder, the form of bipolar disorder closest to the public perception of \u201cmanic depression.\u201d People affected by mania commonly have unusual amounts of energy and experience prominently touchy or exhilarated moods; they also frequently do such things as become unusually talkative, get distracted easily, or display considerable recklessness or misplaced confidence. People with hyperthyroidism sometimes enter a manic state as a result of a thyroid-related overactivation of their adrenal glands, according to the authors of a study published in 2010 in the journal Current Opinion in Psychiatry. Typically, problems with mania appear in the early stages of hyperthyroidism before the body has time to deplete its adrenal gland functions. Because of the similarities between bipolar disorder-related mania and hyperthyroidism-related mania, doctors regularly check for the presence of thyroid problems before making a bipolar disorder diagnosis in their patients. Bipolar Disorder and Hyperthyroidism People with bipolar disorder have increased risks for developing hyperthyroidism or some other type of thyroid gland dysfunction, the National Institute of Mental Health reports. Interestingly, thyroid problems don\u2019t tend to appear in people while they\u2019re experiencing the full-blown mania classically associated with bipolar I disorder. Instead, affected individuals with the greatest chances of developing thyroid difficulties are either in a mixed phase of bipolar illness that features symptoms of both mania and depression, or have a rapid cycling form of bipolar disorder that moves unusually quickly between episodes of partial or full-blown mania, major depression, and mixed symptoms of mania and depression. According to the results of a Danish study published in 2005 in the journal Bipolar Disorders, people who require hospitalization for treatment of bipolar symptoms have unusually high chances of being hospitalized for hyperthyroidism at some point in the future. Treatment Considerations Lithium, one of the mainline treatments for people with bipolar disorder, is known for its ability to alter normal function in the thyroid gland and reduce production of the thyroid gland hormones. This lowered hormone production can lead to the onset of unusually diminished thyroid function, a condition known medically as hypothyroidism. However, use of lithium also sometimes leads to the onset of hyperthyroidism. Doctors treating bipolar disorder must carefully consider the potential effects of lithium use and monitor their patients for any sign of an overactive or underactive thyroid gland.