Thyroid Dysfunction Can Be Mistaken for Mental Illness

The thyroid is a butterfly-shaped gland at the front of the neck. Its job is to produce hormones which regulate our metabolism, that is, the speed at which energy is used by our bodies. Thyroid hormones are secreted into the bloodstream then carried to every tissue and organ in our bodies and help the body keep the brain, heart, muscles, and other organs working as they should. Too much or too little thyroid hormone can affect brain function. If the thyroid is under-active (hypothyroidism) or over-active (hyperthyroidism), the emotional symptoms that one experiences can be similar to the symptoms associated with various mental health disorders.

According to the American College of Endocrinology, thyroid disease is more common than diabetes or heart disease, effecting as many as 30 million Americans. More than half of those people are unaware of their condition, many because they have been misdiagnosed. It is not unlikely that a person reporting symptoms of depression, anxiety, fatigue, insomnia and “brain fog” will mistakenly receive a diagnosis of major depression, general anxiety, or bipolar disorder. They may be prescribed antidepressants, mood stabilizers, sedatives or all three, when in fact what is needed is treatment for thyroid dysfunction.

The chart below shows the similarities of symptoms between a thyroid condition and bipolar disorder.

Symptoms of Thyroid Condition

Symptoms of Bipolar Disorder


  • Depression
  • Weight gain
  • Fatigue
  • Difficulty concentrating
  • Fuzzy thinking
  • Trouble sleeping
Depressive Episode

  • Depressed mood
  • Lack of interest in, or pleasure from, normal daily activities
  • Significant weight loss or gain and/or changes in appetite
  • Insomnia or excessive need for sleep
  • Restlessness or slowed behavior
  • Fatigue or loss of energy
  • Feelings of worthlessness or guilt
  • Inability to think or concentrate
  • Thoughts of death or suicide

  • Anxiety
  • Insomnia
  • Weight loss
Manic Episode

  • Easily distracted
  • Thoughts are racing
  • Experience high levels of self-esteem
  • Need for sleep is reduced
  • Unusually, or excessively, talkative
  • Engage in reckless behavior

According to mainstream medicine, taking blood and measuring levels of TSH (thyroid stimulating hormone), a hormone released by the pituitary gland which regulates the release of hormones by the thyroid, is the “gold standard” for the diagnosis of thyroid dysfunction. According to Mary Shomon in Understanding the TSH Test and Its Controversies, as of 2017, at most laboratories in the United States, the official reference range for the TSH test runs from approximately 0.5 to 4.5 or 5.0 (mIU/L or Milli-International Units/Litre). A patient whose TSH level is within the reference range is considered to have normal thyroid function. However, there is much controversy as to whether or not this range is the best measure of “normal.”

In 2002, the National Academy of Clinical Biochemistry (NACB) issued new guidelines for the diagnosis and monitoring of thyroid disease. It reported that the range for what is considered normal was too wide and actually included people with thyroid disease. In 2003, the American Association of Clinical Endocrinologists (AACE) called for doctors to consider treatment for patients who test outside the boundaries of a narrower margin based on a target TSH level of 0.3 to 3.0, saying they believe the new range would result in proper diagnosis for millions of Americans who suffer from a mild thyroid disorder, but have gone untreated.

TSH alone may not provide a complete picture. Sometimes running a full blood panel that includes Total T4, Free T4, Total T3, Free T3, Reverse T3, and thyroid antibodies may provide more insight into the most appropriate course of treatment.

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