In the early 1900s, doctors often considered depression to be a symptom of low thyroid levels. We now understand that depression is about more than low thyroid, but still, they were onto something. Today many doctors are again turning to thyroid medication for their patients with depression. The long list of symptoms that can be caused by low thyroid also includes anxiety, memory loss, foggy thinking, weight gain, fatigue, dry hair and skin and brittle nails. Low thyroid can also increase the risk of heart disease and Alzheimer’s disease.
Women in particular tend to have symptoms of low thyroid but test “normal” for thyroid levels. However, when doctors give them thyroid medication their symptoms often disappear. This so-called subclinical hypothyroidism may be caused by estrogen dominance or low iodine levels, both conditions which can block thyroid function without causing a drop in thyroid stimulating hormone (TSH), which is what doctors typically test. The best way to diagnose estrogen dominance is a combination of testing estradiol and progesterone levels, and looking at symptoms. It’s more difficult to determine iodine deficiency by symptoms, but iodine levels are easily tested with an iodine urine test.
Thyroid medication is being used in psychiatry to enhance the effectiveness of lithium and the SSRI antidepressants (e.g. Celexa, Prozac, Zoloft). Studies have found that depressed patients who didn’t respond to these medications did better once they were also given thyroid replacement.
In the book “The Thyroid Axis in Psychiatric Disorder” by Russell T. Joffe, M.D. and Anthony J. Levitt, M.D. they say, “In summary, it is important for those having behavioral and/or psychiatric symptoms to know that T3 [a thyroid hormone] is found in large quantities in the limbic system of the brain, the area that is important for emotions such as joy, panic, anger, and fear… and that if you don’t have enough T3, or if its action is blocked, an entire cascade of neurotransmitter abnormalities may ensue and can lead to mood and energy changes.”
The good news is that thyroid medications don’t do a lot of harm, or have serious side effects if used in the lowest possible dose. Most alternatively-oriented doctors use natural dessicated thyroid, which is ground up pork thyroid (e.g. Armour) rather than one of the single thyroid hormones such as T3 (triiodothyronine, Cytomel) or T4 (e.g. thyroxine, Levothyroxine).
It’s probably wise for women with low thyroid symptoms to first check for estrogen dominance and low iodine, since addressing those issues could clear up the problem without resorting to thyroid medications.