Depression is often a sign or symptom of hypothyroidism, or an under-active thyroid gland. When depression is present, it is really important to look at thyroid hormone levels as a potential cause. This is true even in patients with known thyroid conditions undergoing treatment. Often patients with hypothyroidism getting standard treatment with thyroid hormone replacement, still have symptoms consistent with depression. Even more interesting there is an association of T4 and T3 levels with the severity of depression even in patients with normal levels of thyroid stimulating hormone (TSH). TSH is the marker most often used to diagnose hypothyroidism. In patients with depression, therefore it is not enough to just test TSH due to the association of symptom severity with T4/3 levels.

It is not surprising to me that in a recent online survey of patients with the diagnosis of hypothyroidism, a large percentage of patients reported dissatisfaction with their current treatment plan citing the presence of ongoing symptoms. Those receiving levothyroxine or T4 formulations were less satisfied than those receiving naturally desiccated T4/T3 combinations as well as those receiving other combinations of levothyroxine (T4) and liothyronine (T3). We can learn from this that T3 levels seem to be important when it comes to symptoms of hypothyroidism and depression. Some of this is under genetic and epigenetic control with the enzyme deiodinase that converts T4 to T3. This can also be influenced by inflammation, other hormone levels such as cortisol and nutrient deficiencies.

In addition, the therapeutic goal for reduction of depression symptoms in hypothyroidism for TSH is less than the 2.5 MIU/L as shown in at least one study that looked at this specifically.

Treatment Suggestions

If you have the diagnosis of hypothyroidism and are suffering from symptoms of depression, consider the following:

1. Have you had your levels checked recently? Including TSH, T3, T4? Reverse T3? If not maybe you should given the association of T3 levels with depression severity.
2. Consider sources of inflammation. Both hypothyroidism (usually due to Hashimoto’s or autoimmune hypothyroidism) and depression have links with inflammation and inflammatory proteins produced by the body. Common causes of inflammation are food sensitivities, imbalanced gut micro biome, nutrient deficiencies and stealth infections and toxins.
3. Work on self care practices. Prioritize getting adequate sleep (7-8 hours per night). Eat a whole foods diet particularly foods with B vitamins such as leafy greens and fruits and vegetables. Get some exercise daily, preferably spending some time outdoors.

If you have been diagnosed with depression and are wondering if hypothyroidism or an under active thyroid could be the cause, I would recommend items 1 to 3 as well! Get your levels checked, look at possible sources of inflammation and practice self care.

References:
1. Peterson SJ1, Cappola AR2, Castro MR3, Dayan CM4, Farwell AP5, Hennessey JV6, Kopp PA7, Ross DS8, Samuels MH9, Sawka AM10, Taylor PN4, Jonklaas J11, Bianco AC1. Thyroid. 2018 Apr 5.
An Online Survey of Hypothyroid Patients Demonstrates Prominent Dissatisfaction.

2. Berent D1, Zboralski K, Orzechowska A, Gałecki P. Mol Biol Rep. 2014;41(4):2419-25. Epub 2014 Jan 18.
Thyroid hormones association with depression severity and clinical outcome in patients with major depressive disorder.

3. Talaei A, Rafee N, Rafei F, Chehrei A.
BMC Psychiatry. 2017 Sep 7;17(1):327. 1478-9. TSH cut off point based on depression in hypothyroid patients.