Causes of High TSH & Hypothyroidism
1) Iodine Deficiency
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
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) .
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.
4) Lithium Medication or Supplements
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 .
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) .
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 .
In a study with 78 patients, infants with hypothyroidism who were fed soy formula had higher TSH levels than infants fed formula without soy .
7) Vitamin Deficiencies
Another study with 60 people showed that vitamin D deficiency is also associated with hypothyroidism .
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].
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 .
Other studies have reported that up to 30% of diabetic patients may have some type of abnormal thyroid functioning .
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 .
11) Other Toxins
Toxins such as perchlorates found in rocket fuels, thiocyanates, and nitrates can increase TSH levels 
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 .
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) .
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 .
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) .
In rats, a diet high in saturated fat and calories led to thyroid dysfunction by causing low T4 and high TSH levels .
15) Being Overweight
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) .
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 .
16) Certain Medications
Clonidine, an alpha-adrenergic agonist, increased TSH levels .
Metyrapone (Metopirone), used to treat Cushing’s syndrome, can also increase TSH 
One study with 38 cancer patients showed that after chemotherapy with drugs such as docetaxel, TSH levels rose significantly .
17) Radiation Exposure
Treatments that kill or surgically remove thyroid cells, such as radioiodine ablation and thyroidectomy, can also cause hypothyroidism .
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].
18) Pituitary Gland Tumors
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.
The most common symptoms are:
- Fatigue 
- Constipation 
- Weight gain 
- Carpal tunnel syndrome 
- Depression 
- Anxiety 
- Memory problems [76, 77, 78]
- Attention issues 
- Dry skin 
- Sensitivity to the cold 
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 .
Less Common Symptoms
Other symptoms of hypothyroidism can include :
- Low heart rate
- Reduced sweating
- Shortness of breath
- Hair loss
- Dry or yellow skin color
- Hoarse voice
- Skin swelling
- Hearing problems
- Muscle or joint pain
- Slow reflexes
- Menstrual cycle problems like heavy bleeding
- Decreased fertility
- Erectile dysfunction
Health Risks of High TSH
1) Poor Heart Health
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 .
TSH has also been linked to high blood pressure in children, especially in overweight children .
2) High Fat and Cholesterol Levels
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”) .
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 .
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 .
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 .
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) .
5) Risk of Thyroid Cancer
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 .
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 .
How to Lower TSH Levels Naturally
1) Get More Selenium
The World Health Organization recommends a maximum daily intake of 70 micrograms of selenium. Doses over 400 micrograms per day can be toxic .
Some great dietary sources of selenium include :
- Brazil nuts
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 .
Low levels of tyrosine are linked to lower levels of thyroid hormones (and thus, higher TSH), at least in patients with severe infections .
As an added bonus, tyrosine supplements have been shown to enhance cognitive performance as well .
Foods that contain high levels of tyrosine are :
- Chicken and turkey
- Dairy products
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 .
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 .
Supplements may also protect against cognitive impairment caused by hypothyroidism .
Other supplements that can decrease TSH include:
- Vitamin A (if deficient) 
- Vitamin C 
- Vitamin E (if deficient) 
- Alpha-lipoic acid 
- Taurine 
- Insulin plant (Costus pictus) 
5) Check Your Vitamin B12 Levels
A study of 116 people found that vitamin B12 supplements improve symptoms in almost 60% of cases .
6) Get Enough Sleep
Make sure to get enough quality sleep. Sleep restriction increases TSH levels .
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 .
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 .
It’s not surprising then that iodine deficiency is one of the leading causes of hypothyroidism .
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 .
The recommended daily intake of iodine is 150 micrograms .
Consuming too much iodine is dangerous. The upper limit of iodine is about 1,100 micrograms per day, doses above that can be lethal .
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 .
Iodine is important for brain development in kids. Deficiencies during pregnancy can cause a number of complications .
Good food sources of iodine include :
- Seaweed and kelp
- Iodized salt
Look into stress-busting techniques such as practicing yoga . Six months of yoga had beneficial effects on thyroid hormones in women with hypothyroidism.
10) Maybe Increase Dopamine
One study with 20 healthy adults showed that blocking dopamine receptors led to increased TSH levels, further indicating that dopamine inhibits TSH .
11) Maybe Increase Norepinephrine
One study with 62 depressed patients showed that the norepinephrine reuptake inhibitor (NRI) reboxetine reduced TSH .
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 .
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].
A number of different supplements are marketed as promoters of thyroid health. Let’s take a look at all the options.
Multiple products called Thyroid Support are available. These supplements typically contain a variety of vitamins and nutrients, including iodine, tyrosine, selenium, and even ashwagandha.
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 .
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.
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 .
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)
Learn More About TSH
This post is part of a three-part series about TSH.
- Find out how the TSH blood test works and what the normal TSH range in part one
- If your TSH is low and you have an overactive thyroid, read about the causes, symptom, and natural fixes in part three
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