Understand your Thyroid stimulating hormone (TSH) Blood Test Results…

This page helps you to understand blood test results for Thyroid stimulating hormone (TSH) and gives you the reference range to determine if your lab test results mean that you have high, low or normal Thyroid stimulating hormone (TSH) levels. 

We outline the risk factors associated with both raised and lower Thyroid stimulating hormone (TSH) levels.

Reference Ranges for Thyroid stimulating hormone (TSH):

Measurement unit Metric Optimal Borderline Risk
US Conventional Units mU/l 0.3-4.2 4.3-5 <0.3 or > 5
Standard International Units mU/L 0.3-4.2 4.3-5 <0.3 or > 5
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What is Thyroid stimulating hormone (TSH)

Thyroid-stimulating hormone (TSH), is a hormone produced by the pituitary gland, a tiny organ located below the brain and behind the sinus cavities. TSH is often the test of choice for evaluating thyroid function and/or symptoms of a thyroid disorder, including hyperthyroidism or hypothyroidism [132].

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Function of Thyroid stimulating hormone (TSH)

TSH, along with its regulatory hormone thyrotropin releasing hormone (TRH), is part of the feedback system that the body uses to maintain stable amounts of thyroid hormones in the blood. When thyroid hormone concentrations decrease, the production of TSH by the pituitary gland is increased. TSH in turn stimulates the production and release of T4 and T3 by the thyroid gland, a small butterfly-shaped gland that lies at the base of the throat flat against the windpipe. When all three organs are functioning normally, thyroid production turns on and off to maintain relatively stable levels of thyroid hormones in the blood, helping control the rate at which the body uses energy [132].

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Risk factors associated with Thyroid stimulating hormone (TSH)

Overactive Thyroid – If the thyroid releases inappropriately large amounts of T4 and T3, the affected person may experience symptoms associated with hyperthyroidism, such as rapid heart rate, weight loss, nervousness, hand tremors, irritated eyes, and difficulty sleeping. Graves disease is the most common cause of hyperthyroidism. It is a chronic autoimmune disorder in which the affected person’s immune system produces antibodies that act like TSH, leading to the production of excessive amounts of thyroid hormone. In response, the pituitary may produce less TSH, usually leading to a low level in the blood [132].

Underactive Thyroid – If there is decreased production of thyroid hormones by the thyroid (hypothyroidism), the person may experience symptoms such as weight gain, dry skin, constipation, cold intolerance, and fatigue. Hashimoto thyroiditis is the most common cause of hypothyroidism. It is a chronic autoimmune condition in which the immune response causes inflammation and damage to the thyroid as well as the production of autoantibodies. With Hashimoto thyroiditis, the thyroid produces low levels of thyroid hormone. The pituitary may produce more TSH, usually resulting in a high level in the blood [132].

However, the level of TSH does not always predict or reflect thyroid hormone levels. Some people produce an abnormal form of TSH that does not function properly. They often have hypothyroidism despite having normal or even mildly elevated TSH levels. In a variety of thyroid diseases, thyroid hormone levels may be high or low, regardless of the amount of TSH present in the blood [132].

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Notable variations by demographic group

Levels of TSH have been shown to reduce as we get older, particularly over the age of 70 [133].

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Diet to improve Thyroid stimulating hormone (TSH)

There are a number of foods that should be included in the diet of a person who wants to improve thyroid function

Foods Rich in Omega-3 – Essential fatty acids like omega-3 are important for thyroid function. Good food sources of omega-3 include grounded flaxseed or flaxseed oil, chia seeds, hemp seeds, and wild-caught fatty fish like salmon, trout, or tuna.

Nuts – Nuts such as Brazil nuts, hazelnuts, and macadamia nuts are all high in selenium. Selenium is associated with high T4 and TSH, and selenium is required for the conversion, or deiodination of T4 to the active T3.

Probiotic Rich Foods – Intestinal permeability has been proposed as a potential cause of poor thyroid function. In this condition there is an imbalance of good bacteria, or microflora, in the gut. Probiotic foods will help balance gut bacteria, which will also improve thyroid function. Examples of probiotic foods include kimchi, kefir, sauerkraut, natto, miso, and kombucha.

Antioxidant Rich Vegetables and Fruit – The diet should contain plenty of vegetables and fruits that are high in antioxidants. Foods high in antioxidants include apples, blueberries, raspberries, asparagus, and bell peppers. The high fiber in these foods also supports digestion, heart health, and balances blood sugar levels and hormones.

Try to limit:

Sugar and Refined Flour Products – Sugar is known to disrupt the hormone balance important for metabolism; those with weight issues often have thyroid problems. Excess sugar can lead to weight gain, depression, fatigue, mood changes, and hormonal disturbances. There is a lot of added sugar in refined carbohydrate and flour products.

Soy Products – In a study published in the Journal of Clinical Endocrinology & Metabolism in 2010, researchers found that women that consumed soy tripled their risk of hypothyroidism (underactive thyroid).

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Supplements for Thyroid stimulating hormone (TSH)

Vitamin B Complex – All the B vitamins are vital for good thyroid function and they all have a different role to play [138].

Vitamin C – Long standing vitamin C deficiency causes the thyroid gland to secrete too much hormone.  People with an overactive thyroid need extra Vitamin C as this is actually drained from the tissues in their bodies [138].

Vitamin D – It has been found that when people with an overactive thyroid take vitamin D, it counteracts the usual rapid excretion of calcium, and osteoporosis can be avoided [138].

Vitamin E – lack of this vitamin encourages the thyroid gland to secrete too much hormone, as well as too little TSH by the pituitary gland. A higher intake is often needed by people with an overactive thyroid to counteract the large amounts of the vitamin depleted from the system [138].

Magnesium is required for the conversion of T4 into T3 [138].

Selenium – This is a crucial component of the enzyme that converts T4 to T3 in the body.  Without it, T3 cannot be produced in the right amounts, and organs will function as if they were hypothyroid even though blood test levels are normal [138].

Zinc – Research has shown that both hypothyroidism and hyperthyroidism result in zinc deficiency.  It also plays a role in the functioning of the immune system. Zinc is needed to convert T4 into T3 [138].

Iodine – Iodine supplement have received a lot of attention in relation to thyroid function. The Mayo Clinic suggests that Iodine supplements usually aren’t necessary if you live in in most developed countries. It is true that iodine deficiency can cause hypothyroidism. But iodine deficiency is rare in developed countries since the addition of iodine to salt (iodized salt) and other foods.

If iodine deficiency isn’t the cause of hypothyroidism, then iodine supplements provide no benefit and should not be used. In fact, for some people with abnormal thyroid glands, too much iodine can cause or worsen hypothyroidism [137].

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Exercise to improve Thyroid stimulating hormone (TSH)

Exercising with either uncontrolled hyperthyroidism (overactive thyroid) or hypothyroidism (underactive thyroid) can be counterproductive for your health as these conditions increase or depress people’s metabolism, respectively — speeding up or slowing down their heart rate. Therefore it is important to work with your doctor to get any symptoms under control before building back into exercise which is proven to help improve thyroid function over the longer term [139].

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Sleep for Thyroid stimulating hormone (TSH)

An overactive thyroid gland (hyperthyroidism) can cause sleep problems. The disorder overstimulates the nervous system, making it hard to fall asleep, and it may cause night sweats, leading to night-time arousals.

Feeling cold and sleepy is a hallmark of an underactive thyroid (hypothyroidism) [140].

In both cases, treating the underlying condition should help to improve sleep quality. Getting the right amount and quality of sleep should then help to balance hormones and maintain thyroid function over time.