TSH is often the first test doctors use to determine whether you have too little or has too much thyroid hormones. Low TSH is linked to an overactive thyroid or hyperthyroidism. Read on to learn about the causes, symptoms, and natural ways of increasing your TSH levels.

Causes of Low TSH & Hyperthyroidism

Hyperthyroidism is a condition where the thyroid is overactive and produces excess thyroid hormones T3 and T4.

1) Goiters & Grave’s Disease

The most common cause of hyperthyroidism is Graves’ disease, an autoimmune disease where your antibodies act like TSH, leading to overproduction of thyroid hormones [1].

A thyroidectomy is a procedure that removes part- or all of the thyroid gland. It is commonly performed to treat Graves’ disease, thyroid cancer, and various cases of goiter [2, 3].

Goiters are an enlargement of the thyroid gland, and can sometimes be seen as a bulging in the neck area. Goiters are usually a sign of thyroid dysfunction or iodine deficiency [4].

Other common causes of hyperthyroidism are toxic nodular goiters (swollen thyroid – also known as Plummer’s disease) and painless (or “silent”) thyroiditis (a condition where the immune system attacks the thyroid gland, causing it to become inflamed) [5].

2) Mild Iodine Deficiency

Mild iodine deficiency can lead to hyperthyroidism (as the thyroid is over-stimulated to compensate for the mild iodine deficiency) [6, 7].

3) Stress

There are many different ways that stress can impact your T3 and T4 levels.

For example, many studies have suggested that experiencing negative and stressful life events increases the likelihood of developing Graves’ disease, a common cause of hyperthyroidism [8, 9, 10, 11, 12].

However, the evidence is mixed, as a few other human studies have reached the conclusion that stress is not involved in Graves’ disease and related illnesses [13, 14, 15].

Nonetheless, several animal studies support the idea that stress is a contributing factor in thyroid dysfunction. For example, multiple rat studies have found that stress disrupts thyroid function, although in different ways.

Stress-induced by electric shocks to rat tails led to decreases in T3, T4, and TSH [16].

A variety of different chronic stressors (including water or food deprivation, cold temperatures, flashing lights, etc.) may also increase T3 and T4 levels [17].

4) Hormonal Changes in Pregnancy

Because of the hormonal changes and thyroid stimulation that occur during pregnancy, thyroid dysfunction is more common in pregnant women. About 2.1 – 3.4% of pregnant women experience either hypothyroidism or hyperthyroidism [18].

Studies have also found a variety of adverse effects on the children of women with hyperthyroidism. These include low baby weight during pregnancy (intrauterine growth restriction), premature labor and birth, and low birth weight [19, 20, 21].

5) Low-Carb Diets

Going on a ketogenic diet (high-fat, low-carb) may excessively lower TSH [22]

In one study, a high-fat low-carb diet also can decrease T3 levels, and both high-fat low-carb and high protein low carb diets can lower TSH levels [22].

6) Smoking

One study found that smokers have lower TSH levels than non-smokers [23].

7) Certain Medications

Rexinoids (a type of retinoid) may lower thyroid-stimulating hormone levels in rodents, healthy people and cancer patients (possibly by inhibiting TSH secretion and gene expression) [24, 25, 26, 27, 28].

However, one study with 10 patients showed that one type of rexinoid (bexarotene) did not affect TSH levels [29].

A meta-analysis of 7 different studies showed that metformin reduces TSH levels for hypothyroid patients, but not for people with normal thyroid function [30].

Many studies show that interferon-alpha (IFN-alpha, commonly used to treat hepatitis C) has led to increased rates of developing thyroid dysfunction [31, 32, 33, 34, 35].

8) Radiation Exposure

Exposure to radiation in the thyroid area is a big risk factor for developing thyroid cancer, especially for children [36, 37].

A common treatment for cancer itself is radiation therapy. Unfortunately, radiation therapy puts patients at a greater risk for thyroid cancer, as seen in multiple studies involving children [38, 39, 40].

Radiation also increases the risk of developing both hyperthyroidism and hypothyroidism [41, 42, 43, 44].

Limitations and Caveats

A lot of studies in this article talk about associations between low levels of TSH and certain conditions. These studies are relevant but it is important to note that correlation does not imply causation. Just because abnormal TSH levels are linked to specific conditions it does not mean that TSH caused these conditions. It could be the case that the disease caused the abnormal TSH levels, or some underlying factor caused both. Without further studies, it’s impossible to know which is the case.

Symptoms of Low TSH & Hyperthyroidism

Common Symptoms

A study of 84 hyperthyroidism patients found that the most common symptoms include [45]:

  • Nervousness
  • Increased sweating
  • Extreme thirst
  • Hyperactive reflexes
  • Heat intolerance
  • Goiters

Less Common Symptoms

Other, less common, symptoms include [5, 46, 45]:

  • Fatigue
  • Muscle weakness
  • Sleep difficulties
  • Weight loss
  • Increased eye sensitivity, leading to crying or tearing up, or painful sensitivity to light (photophobia)
  • Increased heart rate (tachycardia)
  • Swelling of tissues (peripheral edema)
  • Palpitations
  • “Lid lag” (delay in the movement of eyelids)
  • Excess stool production (more than 3x/day)

Hyperthyroidism can also cause psychological symptoms such as apathy, although this was found to be more common in elderly patients (> 70 years old) [45].

Hyperthyroidism can also cause a number of symptoms that affect the mouth, jaw, and throat, such as burning mouth syndrome, osteoporosis of jawbones, swollen or enlarged thyroid tissue (goiter), and higher chance to develop cavities and periodontal disease [47].

Hyperthyroidism is known to reduce bone mass (by increasing the activity of osteoclasts, the cells that break down bone tissue), which can lead to osteoporosis [48, 49, 50].

Hyperthyroidism is linked with an increase in oxidative stress (due to increases in reactive oxygen species and impairment of antioxidants) [51, 52, 53, 54].

Health Risks of Low TSH

1) Linked with Worse Mental Health

Low TSH levels may contribute to declines in mental health among the elderly.

In a study with 293 adults over the age of 65, low TSH levels were linked with deteriorating cognitive function [55].

Another study of 313 elderly adults showed that low TSH levels were associated with worsening cognitive function as well as dementia [56].

In a study involving 1,843 people aged 55 and over, those with low TSH levels were 3 times more likely to develop dementia or Alzheimer’s disease [57].

A study with 1,503 elderly adults showed that those with low levels of TSH had an increased likelihood of having depressive symptoms or developing depression later on [58].

2) Linked to Worse Bone Health

Having higher TSH levels may also support bone health in the elderly.

Low TSH levels were linked to a lower bone mineral density in a study with 674 elderly women [59].

In a study with 686 elderly women, those with low TSH levels had a much higher risk of fracturing their hip bones or spinal cord [60].

A study with over 14,000 patients showed that elderly women (but not elderly men) with low TSH levels had a higher likelihood of hip fractures [61].

3) Linked with Shorter Lifespan

Many studies show that TSH levels naturally increase as you get older [55, 62, 63, 64, 65].

However, although high levels of TSH are generally associated with negative outcomes in adults and children, this might not be the case for the elderly. In fact, many studies suggest the opposite – that in older people, it is actually lower TSH levels that cause problems, while higher levels may be protective.

A number of findings suggest that high TSH levels may be beneficial for living longer.

A very elderly group of people (with a median age of 98) had significantly higher levels of TSH when compared to a control group with a median age of 72 [66].

For 2,290 elderly adults aged 70-79, those with slightly elevated TSH levels had less difficulty walking, were able to walk faster, and were in better shape than those with normal TSH levels [67].

A study with 558 adults from ages 85 to 89 found that those with the highest TSH levels had the lowest overall risk of dying [68].

How to Increase TSH Levels Naturally

1) Increase Your Iodine Intake (If Mildly Deficient)

One study with 36 healthy patients showed that eating kelp, which is high in iodine, increased thyroid-stimulating hormone levels [69].

2) Exercise

Exercise can help naturally boost TSH and T4 levels. One study with 60 male athletes showed that moderate and high-intensity training led to increases in TSH and T4 [70].

3) Stop Smoking

Stop or reduce smoking, because smoking decreases TSH levels [23].

4) Reduce Alcohol

Reduce or stop alcohol consumption [71]. Alcohol use is associated with decreased TSH production.

5) Increase Your Carb Intake

If you are on a low-carbohydrate diet, you may need to increase your carbohydrate consumption [22].

6) Supplements

The following supplements can help increase TSH:

  • Green Tea [72]
  • Acetyl-l-carnitine [73]

7) Maybe Increase Serotonin

Rat studies show that serotonin can increase TSH levels. You may want to look into natural ways of increasing your serotonin levels [74, 75].

Unsuprisingly, antidepressant medications that increase serotonin have a similar effect. Selective serotonin reuptake inhibitor (SSRI) sertraline increased TSH in one study with 62 depressed patients [76].

One study with 19 depressed patients treated with SSRIs showed a relationship between TSH levels and symptom improvement. Patients with lower levels of TSH prior to treatment had greater improvements in their depressive symptoms [77].

8) Avoid Corticosteroids

Studies have shown that glucocorticoids (steroid hormones such as cortisol and dexamethasone) lower TSH levels in both hypothyroid patients and healthy people (potentially by inhibiting TRH) [78, 79, 80, 81].

9) Other Hormones to Look Into

The growth hormone-inhibiting hormone (GHIH) somatostatin (and related compounds) can also lower thyroid-stimulating hormone levels [82, 83, 84].

Rat studies show that testosterone may act to increase TSH levels [85, 86].

A Word About Conventional Treatments & their Side Effects

The most common treatment for hyperthyroidism in the United States is radioiodine ablation, which is generally safe. Radioactive iodine destroys thyroid cells, and therefore fewer thyroid hormones are produced [5, 87].

The major side-effect of radioiodine ablation is hypothyroidism, including acute thyroiditis [87, 88].

Other treatment options for hyperthyroidism include thyroidectomy (surgical removal of the thyroid). Common complications with thyroidectomy are hypothyroidism, low calcium levels (hypocalcemia), and vocal cord paralysis [89, 90].

Antithyroid medications are also commonly prescribed. These include Tapazole (methimazole) and propylthiouracil (which stop thyroid hormone synthesis) or cholestyramine (which promotes excretion of excess thyroid hormones) [5, 87].

Additionally, beta-blockers like propranolol, atenolol, and nadolol can be taken to ease hyperthyroid symptoms [5, 87].

One study with 449 Graves’ disease patients showed that side-effects of antithyroid medications include skin rashes, liver damage (hepatotoxicity), and low white blood cell count (agranulocytosis/neutropenia) [91].

Other side-effects of antithyroid medications are joint pain, swelling, nausea, and vomiting [92].

Learn More About TSH

This post is part of a three-part series about TSH.

Irregular TSH Levels?

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About the Author

Pranab Karki, BSc

BS (Neuroscience & Behaviour)

Received his BS in Neuroscience and Behavior from Wesleyan University and is getting his MS in Biochemistry and Cell Biology at Stony Brook University.

He loves helping people learn how to improve their overall well being. He is most interested in fitness, how the brain works, mental health, and enjoys sharing that information with others. He believes that the more people understand science, the better the world will be.

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