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

Causes of High TSH & Hypothyroidism

Hypothyroidism – the opposite of hyperthyroidism – is when the thyroid is underactive and doesn’t produce enough T3 and T4 hormones.

1) Iodine Deficiency

Globally, the most common cause of hypothyroidism is iodine deficiency [1].

Thyroid hormones are made from the chemical iodine, which humans need to get from the food they eat. Not getting enough iodine in your diet (severe iodine deficiency) can lead to hypothyroidism, and may even cause goiters (a large swelling of the thyroid gland that bulges out from the neck) [2, 3].

2) Iodine Excess

Many studies also show that excessive iodine intake can also lead to hyperthyroidism (>150 μg for people with existing thyroid diseases, or >1,100 μg for health individuals) [4, 5, 6, 7]

For example, children living in an area with abnormally high iodine concentrations in their drinking water show higher rates of thyroid dysfunction (increased levels of TSH and thyroid antibodies) [8].

Animal and cell studies show that excess iodine can be toxic to the thyroid gland and lead to thyroid cell death [9, 10, 11].

3) Autoimmune Thyroid Problems

High TSH can be caused by primary hypothyroidism, which is when TSH levels rise due to issues with the thyroid gland such as Hashimoto’s thyroiditis and other forms of hypothyroidism.

Another relatively common cause of hypothyroidism is Hashimoto’s thyroiditis (an autoimmune disorder), where the body’s own immune system attacks and gradually destroys the thyroid gland [1].

4) Lithium Medication or Supplements

Many studies have shown that lithium therapy leads to increased rates of developing hypothyroidism and goiters [12, 13, 14, 15].

5) Low-Carb Diets

Going on a ketogenic diet (high-fat, low-carb) is popular with many people, and is even a common treatment for people with epilepsy. However, the ketogenic diet can interfere with thyroid function. For example, a low-fat diet caused hypothyroidism in 17% of 120 epilepsy patients in one study [16].

6) Soy

Soy-based foods contain compounds that can mimic or affect the activity of several hormones (such as estrogen). Because of this, soy foods may also interfere with proper thyroid function [17].

One study with 189 children showed that those who were fed soy milk formulas had a much greater chance of developing autoimmune thyroid disorders later on (such as Hashimoto’s disease) [18].

Three months of increased soy intake led to goiters, sleepiness, and constipation in a study involving 37 previously-healthy adults. However, the symptoms went away after stopping excess soybean intake [19].

In a study with 78 patients, infants with hypothyroidism who were fed soy formula had higher TSH levels than infants fed formula without soy [20].

7) Vitamin Deficiencies

Many studies show that vitamin D deficiency is linked to thyroiditis/autoimmune thyroid disorders [21, 22, 23, 24, 25].

Another study with 60 people showed that vitamin D deficiency is also associated with hypothyroidism [26].

Vitamin B12 deficiency is linked to hypothyroidism as well, as seen in a study with 116 patients [27].

8) Stress

There are many different ways that stress can impact your T3 and T4 levels. On the one hand, it’s a possible cause of hyperthyroidism and Grave’s disease. On the other hand, it may disrupt the thyroid and lead to hypothyroidism. Stressing rats with electric shocks, for example, lowers their T3, T4, and TSH. Social stress also induced hypothyroidism in rats [28, 29].

9) Diabetes

Diabetes is strongly related to thyroid dysfunction – especially hypothyroidism – which can greatly influence your T3 and T4 levels.

Biological signs of low thyroid activity (such as high TSH and low T4 levels in the blood) correlate with an increased risk for diabetes [30].

A study of 202 diabetic patients found that 11% had hypothyroidism, which was ten times higher than the rate in the general population [31, 32].

Other studies have reported that up to 30% of diabetic patients may have some type of abnormal thyroid functioning [33].

Many studies show that metformin, a drug used to treat diabetes, lowers TSH levels, putting diabetes patients at even greater risk of hypothyroidism [34, 35, 36, 37].

10) Excess Fluoride

One study with 70 school children showed that those living in areas with excess fluoride in the water had higher levels of TSH [38].

11) Other Toxins

Toxins such as perchlorates found in rocket fuels, thiocyanates, and nitrates can increase TSH levels [39]

12) Polycystic Ovary Syndrome (PCOS)

Women with polycystic ovary syndrome (PCOS) are more likely to experience thyroid dysfunction and signs of hypothyroidism such as autoimmune thyroiditis (like Hashimoto’s disease), high TSH levels, and goiters. Hypothyroidism can cause ovarian cysts to develop but is unlikely to cause PCOS itself [40, 41, 42].

13) 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 [43].

One study with 482 hypothyroid pregnant women showed that if these thyroid problems are treated, there is no increased risk to their children. However, the mothers still have an increased likelihood of developing high blood pressure and liver and kidney damage (preeclampsia) [44].

However, pregnancy-related thyroid problems can cause developmental issues in children if left untreated. The children of 62 women who had hypothyroidism performed worse on a variety of tests that measured their intelligence (IQ), attention, language and reading skills, and performance in school [45].

14) Overeating

Overeating is another common cause of thyroid dysfunction. A study found that chronic overeating led to an increase in T3 levels over both the short- and long-term (from 3 weeks up to 7 months) [46].

In rats, a diet high in saturated fat and calories led to thyroid dysfunction by causing low T4 and high TSH levels [47].

15) Being Overweight

Directly tied to the overeating, being severely overweight can also raise TSH levels [48, 49].

Two separate studies have shown that among women, overweight and obese patients have higher TSH levels than normal-weight patients. This includes people with higher overall body weight and body mass index (BMI), larger waist size, and higher body fat percentage [50, 49].

Another study found that, compared to women with low TSH levels, healthy young women with high TSH levels were found to be twice as likely to have metabolic syndrome (a condition that causes obesity, high blood pressure, and high levels of sugar, fat, and cholesterol in the blood) [51].

The link between TSH and obesity doesn’t apply only to women, either: two large-scale studies have shown that higher TSH levels are associated with a higher BMI in both male and female patients alike [52, 53].

TSH is involved in the weight of children as well. Obese and overweight children have higher TSH levels, and these high levels are linked to increases in cholesterol, fat, and blood pressure [54].

16) Certain Medications

Various opioids including morphine, methadone, and buprenorphine have been shown to increase TSH levels [55, 56, 57, 58, 59].

Clonidine, an alpha-adrenergic agonist, increased TSH levels [59].

Metyrapone (Metopirone), used to treat Cushing’s syndrome, can also increase TSH [60].

One study with 38 cancer patients showed that after chemotherapy with drugs such as docetaxel, TSH levels rose significantly [61].

17) Radiation Exposure

Treatments that kill or surgically remove thyroid cells, such as radioiodine ablation and thyroidectomy, can also cause hypothyroidism [62].

Exposure to radiation in the thyroid area is a big risk factor for developing thyroid cancer, especially for children [63, 64].

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 [65, 66, 67].

Radiation also increases the risk of developing both hyperthyroidism and hypothyroidism [68, 69, 70, 71].

18) Pituitary Gland Tumors

Although rare, tumors of the pituitary gland (adenomas) can sometimes cause excess TSH secretion. This can lead to hyperthyroidism or hyperthyroid symptoms [72, 73].

Limitations and Caveats

A lot of studies in this article talk about associations between high 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 High TSH & Hypothyroidism

Hypothyroidism causes a variety of physical and psychological symptoms.

Common Symptoms

The most common symptoms are:

Hypothyroidism may also cause a number of symptoms that affect the mouth, such as mouth breathing, thick lips, small jaw (micrognathia), thin tooth enamel (enamel hypoplasia), tongue swelling or inflammation, enlarged salivary glands, distorted sensations of taste (dysgeusia), and more [81].

Less Common Symptoms

Other symptoms of hypothyroidism can include [82]:

  • Low heart rate
  • Reduced sweating
  • Shortness of breath
  • Hair loss
  • Dry or yellow skin color
  • Hoarse voice
  • Skin swelling
  • Goiters
  • Hearing problems
  • Muscle or joint pain
  • Slow reflexes
  • Menstrual cycle problems like heavy bleeding
  • Decreased fertility
  • Erectile dysfunction

When prolonged, hypothyroidism can also lead to stunted growth, short height, and delayed bone formation (slowing down of bone growth) [83, 84, 85].

Hypothyroidism is also linked with an increase in oxidative stress (due to increases in reactive oxygen species and impairment of antioxidants) [86, 87, 88, 89].

Health Risks of High TSH

1) Poor Heart Health

A study with over 30,000 people revealed that people with higher TSH levels tended to also have higher blood pressure [90].

A meta-analysis of data from over 55,000 patients demonstrated that people with very high TSH levels have a significantly higher chance of developing (and dying from) coronary heart disease [91].

Another study with 314 patients at risk for heart disease found that high levels of “macro TSH” (TSH fused to an antibody) were associated with lower sleep quality [92].

TSH has also been linked to high blood pressure in children, especially in overweight children [54].

2) High Fat and Cholesterol Levels

Two studies have reported that higher TSH levels are linked to higher levels of fat (triglycerides) and “bad” cholesterol (low-density lipoproteins, or “LDL”) [93, 94].

Another study with almost 21,000 people showed similar results, and also found that higher TSH levels are correlated with lower levels of “good” cholesterol (high-density lipoproteins, or “HDL”) [95].

3) Pregnancy Issues

TSH levels were significantly higher among women who were unable to get pregnant after 1 year of trying (unexplained infertility) when compared to a control group [96].

Levothyroxine is a drug used to treat thyroid problems and is more commonly given during pregnancy. One study looked at 1,013 women treated with Levothyroxine and found that many of them had increased TSH levels, which was associated with an increased risk of miscarriage [97].

In a study with over 184,000 women, mothers with high TSH levels 6 months before conceiving had an increased likelihood of spontaneous abortion (miscarriage before 20 weeks), stillbirth, premature birth, and other delivery-related issues [98].

4) Inflammation

Patients given 0.9 mg of TSH for 2 days had impaired blood vessel function, which was possibly due to inflammation and oxidative stress (study with 24 women) [99].

In two animal studies, TSH increased levels of the major inflammatory factors tumor necrosis factor (TNF) and interleukin-6 (IL-6) [100, 101].

5) Risk of Thyroid Cancer

Various studies including a meta-analysis have found that having a high TSH level is a risk factor for developing thyroid cancer [102, 103, 104, 105].

Another study showed that for 126 patients with a specific type of thyroid cancer (papillary thyroid microcarcinoma), high TSH levels were correlated with faster cancer progression [106].

6)  Stress

In a study of 54 healthy young adults, higher levels of TSH were associated with higher levels of the stress hormone cortisol, suggesting that TSH may make the body more sensitive to the effects of stress [107].

How to Lower TSH Levels Naturally

1) Get More Selenium

Selenium is important for thyroid health as it helps convert T4 into T3. Multiple studies show that selenium can reduce T4 levels [108, 109].

Furthermore, areas with high rates of goiter are linked with selenium deficiency and decreased antioxidant (glutathione) levels. Supplementation with selenium raised both to normal levels [110].

The World Health Organization recommends a maximum daily intake of 70 micrograms of selenium. Doses over 400 micrograms per day can be toxic [111].

Some great dietary sources of selenium include [111]:

  • Brazil nuts
  • Garlic
  • Onion
  • Salmon
  • Eggs
  • Beef

2) Increase Your Thyrosine Intake

Research has not looked at the benefits of tyrosine supplements on thyroid disorders, but we do know it is important.

Tyrosine is an amino acid that is used to make T3 and T4 [112].

Low levels of tyrosine are linked to lower levels of thyroid hormones (and thus, higher TSH), at least in patients with severe infections [112].

As an added bonus, tyrosine supplements have been shown to enhance cognitive performance as well [113].

Foods that contain high levels of tyrosine are [114]:

  • Chicken and turkey
  • Fish
  • Dairy products
  • Peanuts
  • Bananas

3) Consider Ashwagandha Supplements

The Ayurvedic herb ashwagandha can also help with thyroid issues. One study with 50 people showed that patients with mild hypothyroidism who took Ashwagandha had improved levels of TSH, T3, and T4 compared to placebo [115].

4) Supplement with Fish Oil & Other Nutrients

A few animal studies show that fish oil supplements may benefit those with thyroid problems.

One rat study found that the PUFAs in fish oil can enhance the action of thyroid hormones [116].

Supplements may also protect against cognitive impairment caused by hypothyroidism [117].

Other supplements that can decrease TSH include:

  • Vitamin A (if deficient) [118]
  • Vitamin C [119]
  • Vitamin E (if deficient) [119]
  • Alpha-lipoic acid [120]
  • Taurine [121]
  • Insulin plant (Costus pictus) [122]

5) Check Your Vitamin B12 Levels

Vitamin B12 deficiencies are very common in people with thyroid disorders. According to some estimates, about 40% of people with hypothyroidism have low levels of vitamin B12 [123].

Correcting this deficiency can improve certain symptoms, including weakness, memory difficulties, and depression [27].

A study of 116 people found that vitamin B12 supplements improve symptoms in almost 60% of cases [27].

6) Get Enough Sleep

Make sure to get enough quality sleep. Sleep restriction increases TSH levels [124].

7) Stay Away from Dairy

People with Hashimoto’s thyroiditis are often lactose intolerant. If you are lactose intolerant, restricting lactose intake may help thyroid functioning. One study with 83 patients with Hashimoto’s thyroiditis showed that a lactose-free diet led to decreased TSH levels for patients with lactose intolerance [125].

8) Increase Your Iodine Intake (If Deficient)

Our body needs adequate amounts of iodine to make thyroid hormones. Since we can’t produce iodine, we get all of it from food [7].

It’s not surprising then that iodine deficiency is one of the leading causes of hypothyroidism [7].

So should you take iodine supplements?

The answer is a bit unclear.

People in the U.S. typically get more than enough iodine from their diets. Especially since the creation of iodized salt, iodine deficiency has not been a major problem [126].

The recommended daily intake of iodine is 150 micrograms [39].

Consuming too much iodine is dangerous. The upper limit of iodine is about 1,100 micrograms per day, doses above that can be lethal [127].

A study of 256 healthy adults found that iodine supplements can cause hypothyroidism. This happened when subjects took more than 800 micrograms each day. Additionally, too much iodine increases Th1 and Th17 immune responses. In turn, excess iodine supplementation may worsen inflammation and autoimmune issues [128, 129].

Only people who are not getting enough dietary iodine may benefit from supplements, especially pregnant women and children who are particularly vulnerable to deficiency [130].

Iodine is important for brain development in kids. Deficiencies during pregnancy can cause a number of complications [130].

Good food sources of iodine include [7]:

  • Seafood
  • Seaweed and kelp
  • Bread
  • Milk
  • Iodized salt

9) De-stress

Look into stress-busting techniques such as practicing yoga [131]. Six months of yoga had beneficial effects on thyroid hormones in women with hypothyroidism.

10) Maybe Increase Dopamine

Studies and reports show that dopamine (and similar compounds) inhibits thyroid-stimulating hormone [132, 133, 134].

One study with 20 healthy adults showed that blocking dopamine receptors led to increased TSH levels, further indicating that dopamine inhibits TSH [135].

In mouse studies, dopamine, epinephrine, and norepinephrine have been shown to counteract the effects of TSH by blocking the release of T4 into the bloodstream [136, 137, 138].

11) Maybe Increase Norepinephrine

One study with 62 depressed patients showed that the norepinephrine reuptake inhibitor (NRI) reboxetine reduced TSH [139].

12) Avoid Gluten (if Sensitive)

If you are sensitive to gluten, avoid gluten-containing foods. Maintaining a strict gluten-free diet can help normalize thyroid hormones in people with celiac disease [140].

13) Look into Thyroid Supplements

Although levothyroxine therapy is considered to be one of the best options for treating hypothyroidism, it comes with many side effects that are hard to tolerate. Side effects of levothyroxine include hives (or other allergic reactions), chest pain, fast heartbeat, seizures, tremors, and headaches [141, 142, 143].

Many people prefer dried thyroid extracts or thyroid support supplements to levothyroxine [144, 145, 146].

A number of different supplements are marketed as promoters of thyroid health. Let’s take a look at all the options.

Thyroid Support

Multiple products called Thyroid Support are available. These supplements typically contain a variety of vitamins and nutrients, including iodine, tyrosine, selenium, and even ashwagandha.

Most of these ingredients are indeed important for thyroid health, but it’s unclear how beneficial supplementation is [45, 50].

Thyroid Glandular and Desiccated Thyroid Gland

Thyroid Glandular or Raw Thyroid are the names of another popular type of supplement.

These products contain thyroid gland tissue usually taken from cows. Some products also include extracts from other glands, like the pituitary and adrenal tissue.

One study from the ‘90s analyzing three thyroid gland supplements revealed that none contained T4 and only two might’ve contained some T3. At doses two times higher than recommended on the supplement label, these products had no effect on thyroid lab markers in healthy volunteers [61].

Based on these studies, it’s highly questionable if OTC thyroid gland supplements work.

Armour Thyroid and NP Thyroid, on the other hand, contain the crushed (desiccated) thyroid glands of pigs. Based on the manufacturers’ claims, both products should provide a consistent amount of T3 (9mcg) and T4 (38 mcg) per grain of thyroid.

Clinical reports suggest Armour Thyroid may be useful for mild (sub-clinical) or diagnosed (clinical) hypothyroidism [147, 148].

Both Armour Thyroid and NP Thyroid require a prescription in the US. Despite this, some people use them for weight loss without medical supervision. In one case, Armour Thyroid use along with testosterone caused serious side effects in a 32-year-old bodybuilder who wanted to lose weight [149].

Consult a doctor before using Armour Thyroid or NP Thyroid and provide them with a full list of all the supplements and medications you’re taking.

14) Avoid Coffee (if on Levothyroxine)

Limiting how much coffee you drink may help with thyroid function if you are taking levothyroxine. One study found that coffee blocks T4 from being properly absorbed by the body [150].

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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