Thyroid Stimulating Hormone (TSH)
Thyroid Stimulating Hormone (TSH)
Thyroid stimulating hormone (TSH) is a hormone released by the pituitary gland that controls thyroid hormon release, affecting body metabolism.
Thyroid stimulating hormone (TSH) is a hormone released by the pituitary gland that controls thyroid hormon release, affecting body metabolism.
Thyroid Stimulating Hormone (TSH)
Normal range
Normal range
0.35-5.5 mIU/L
0.35-5.5 mIU/L
Normal range
0.35-5.5 mIU/L
0.35-5.5 mIU/L
Normal range
Thyroid Stimulating Hormone (TSH)
Thyroid Stimulating Hormone (TSH)
Thyroid stimulating hormone (TSH) is a hormone released by the pituitary gland that controls thyroid hormon release, affecting body metabolism.
Thyroid Stimulating Hormone (TSH)
Normal range
0.35-5.5 mIU/L
Normal range
0.35-5.5 mIU/L
0.35-5.5 mIU/L
Normal range
Thyroid Stimulating Hormone (TSH)
Thyroid Stimulating Hormone (TSH)
Thyroid stimulating hormone (TSH) is a hormone released by the pituitary gland that controls thyroid hormon release, affecting body metabolism.
Thyroid Stimulating Hormone (TSH)
Normal range
0.35-5.5 mIU/L
Normal range
0.35-5.5 mIU/L
0.35-5.5 mIU/L
Normal range
Thyroid Stimulating Hormone (TSH)
Dr. Jack Devin
MBBS
Your Thyroid's Master Controller
Your Thyroid's Master Controller
TSH is the command centre hormone that controls your thyroid gland's activity. Produced by your pituitary gland, TSH tells your thyroid exactly how much thyroid hormone to produce. When TSH levels are balanced, your thyroid produces the right amount of hormones to keep your metabolism, energy levels, and countless other body functions running smoothly. However, when TSH levels go awry, it signals that your thyroid system is struggling—potentially affecting everything from your heart rate to your mood.
TSH is the command centre hormone that controls your thyroid gland's activity. Produced by your pituitary gland, TSH tells your thyroid exactly how much thyroid hormone to produce. When TSH levels are balanced, your thyroid produces the right amount of hormones to keep your metabolism, energy levels, and countless other body functions running smoothly. However, when TSH levels go awry, it signals that your thyroid system is struggling—potentially affecting everything from your heart rate to your mood.
When TSH Levels Are Too High
When TSH Levels Are Too High
When TSH Levels Are Too High
Discover how elevated TSH signals an under-active thyroid and the widespread symptoms that can affect your daily life.
Read more
When TSH Levels Are Too Low
When TSH Levels Are Too Low
When TSH Levels Are Too Low
Learn why low TSH indicates an overactive thyroid and the serious health considerations.
Read more
What Influences Your TSH Levels?
What Influences Your TSH Levels?
What Influences Your TSH Levels?
From autoimmune conditions to medications, understand the key factors that can disrupt your thyroid's delicate control system.
Read more
Understanding Your Results
Understanding Your Results
Understanding Your Results
Decode your TSH numbers and know exactly what your levels mean for your thyroid health and overall wellbeing.
Read more
When TSH Levels Are Too High
Significantly elevated TSH levels typically indicate an underactive thyroid gland that isn't producing enough thyroid hormones. Your pituitary gland responds by pumping out more TSH, desperately trying to stimulate your sluggish thyroid into action. This condition, called hypothyroidism, can leave you feeling like your body's engine is running in slow motion. Borderline high or low levels may not be clinically significant. If you are already on thyroid medication, these levels can help guide your dose and treatment.
Common symptoms include persistent fatigue, unexplained weight gain, feeling cold all the time, dry skin and hair, constipation, depression, brain fog, and muscle weakness. Many people describe feeling like they're "running on empty" despite getting adequate sleep. Women may experience irregular menstrual cycles or fertility issues.
In severe cases, untreated hypothyroidism can lead to myxoedema—a serious condition characterised by extreme fatigue and decreased mental function. High TSH levels can contribute to elevated cholesterol, increased cardiovascular risk, and fertility problems.
When TSH Levels Are Too High
Significantly elevated TSH levels typically indicate an underactive thyroid gland that isn't producing enough thyroid hormones. Your pituitary gland responds by pumping out more TSH, desperately trying to stimulate your sluggish thyroid into action. This condition, called hypothyroidism, can leave you feeling like your body's engine is running in slow motion. Borderline high or low levels may not be clinically significant. If you are already on thyroid medication, these levels can help guide your dose and treatment.
Common symptoms include persistent fatigue, unexplained weight gain, feeling cold all the time, dry skin and hair, constipation, depression, brain fog, and muscle weakness. Many people describe feeling like they're "running on empty" despite getting adequate sleep. Women may experience irregular menstrual cycles or fertility issues.
In severe cases, untreated hypothyroidism can lead to myxoedema—a serious condition characterised by extreme fatigue and decreased mental function. High TSH levels can contribute to elevated cholesterol, increased cardiovascular risk, and fertility problems.
When TSH Levels Are Too High
Significantly elevated TSH levels typically indicate an underactive thyroid gland that isn't producing enough thyroid hormones. Your pituitary gland responds by pumping out more TSH, desperately trying to stimulate your sluggish thyroid into action. This condition, called hypothyroidism, can leave you feeling like your body's engine is running in slow motion. Borderline high or low levels may not be clinically significant. If you are already on thyroid medication, these levels can help guide your dose and treatment.
Common symptoms include persistent fatigue, unexplained weight gain, feeling cold all the time, dry skin and hair, constipation, depression, brain fog, and muscle weakness. Many people describe feeling like they're "running on empty" despite getting adequate sleep. Women may experience irregular menstrual cycles or fertility issues.
In severe cases, untreated hypothyroidism can lead to myxoedema—a serious condition characterised by extreme fatigue and decreased mental function. High TSH levels can contribute to elevated cholesterol, increased cardiovascular risk, and fertility problems.
When TSH Levels Are Too Low
Low TSH levels usually signal an overactive thyroid that's producing excessive thyroid hormones. Your pituitary gland responds by dramatically reducing TSH production, trying to slow down your hyperactive thyroid. This condition, hyperthyroidism, can make you feel like your body's accelerator is stuck.
Symptoms often include rapid weight loss despite increased appetite, racing heart, feeling hot and sweaty, anxiety or irritability, trembling hands, difficulty sleeping, frequent bowel movements, and muscle weakness. Some people experience bulging eyes or a visibly enlarged thyroid gland (goitre).
When TSH Levels Are Too Low
Low TSH levels usually signal an overactive thyroid that's producing excessive thyroid hormones. Your pituitary gland responds by dramatically reducing TSH production, trying to slow down your hyperactive thyroid. This condition, hyperthyroidism, can make you feel like your body's accelerator is stuck.
Symptoms often include rapid weight loss despite increased appetite, racing heart, feeling hot and sweaty, anxiety or irritability, trembling hands, difficulty sleeping, frequent bowel movements, and muscle weakness. Some people experience bulging eyes or a visibly enlarged thyroid gland (goitre).
When TSH Levels Are Too Low
Low TSH levels usually signal an overactive thyroid that's producing excessive thyroid hormones. Your pituitary gland responds by dramatically reducing TSH production, trying to slow down your hyperactive thyroid. This condition, hyperthyroidism, can make you feel like your body's accelerator is stuck.
Symptoms often include rapid weight loss despite increased appetite, racing heart, feeling hot and sweaty, anxiety or irritability, trembling hands, difficulty sleeping, frequent bowel movements, and muscle weakness. Some people experience bulging eyes or a visibly enlarged thyroid gland (goitre).
What Influences Your TSH Levels
Factors That Can Raise TSH: Several conditions and factors can elevate your TSH levels: Hashimoto's thyroiditis (an autoimmune condition), iodine deficiency, certain medications (lithium, amiodarone, some psychiatric drugs), thyroid surgery or radioactive iodine treatment, pituitary disorders, severe illness or stress, and genetic factors affecting thyroid function.
Factors That Can Lower TSH: Various conditions can suppress TSH production: Graves' disease (an autoimmune condition), thyroiditis (inflammation of the thyroid), certain medications, pregnancy, and pituitary gland disorders.
Severe dieting, extreme stress, and certain supplements can also temporarily affect TSH levels
Managing Your TSH Levels
Supporting Healthy Thyroid Function: Whilst you cannot directly control your TSH levels, you can support optimal thyroid function through lifestyle choices. Ensure adequate iodine intake (sources include iodised salt, seafood, and dairy products) but avoid excessive amounts. Include selenium-rich foods like Brazil nuts, which support thyroid hormone production.
Manage stress through regular exercise, adequate sleep (7-9 hours nightly), and stress-reduction techniques like meditation or yoga. Chronic stress can disrupt the delicate hormone balance that controls TSH production.
When Medical Treatment Is Needed: Significantly abnormal TSH levels typically require medical intervention. Hypothyroidism is usually treated with synthetic thyroid hormone replacement (levothyroxine), which can effectively restore normal hormone levels and relieve symptoms.
Hyperthyroidism treatments vary depending on the cause and may include anti-thyroid medications, radioactive iodine therapy, or surgery. Your doctor will determine the most appropriate treatment based on your specific condition, age, and overall health.
What Influences Your TSH Levels
Factors That Can Raise TSH: Several conditions and factors can elevate your TSH levels: Hashimoto's thyroiditis (an autoimmune condition), iodine deficiency, certain medications (lithium, amiodarone, some psychiatric drugs), thyroid surgery or radioactive iodine treatment, pituitary disorders, severe illness or stress, and genetic factors affecting thyroid function.
Factors That Can Lower TSH: Various conditions can suppress TSH production: Graves' disease (an autoimmune condition), thyroiditis (inflammation of the thyroid), certain medications, pregnancy, and pituitary gland disorders.
Severe dieting, extreme stress, and certain supplements can also temporarily affect TSH levels
Managing Your TSH Levels
Supporting Healthy Thyroid Function: Whilst you cannot directly control your TSH levels, you can support optimal thyroid function through lifestyle choices. Ensure adequate iodine intake (sources include iodised salt, seafood, and dairy products) but avoid excessive amounts. Include selenium-rich foods like Brazil nuts, which support thyroid hormone production.
Manage stress through regular exercise, adequate sleep (7-9 hours nightly), and stress-reduction techniques like meditation or yoga. Chronic stress can disrupt the delicate hormone balance that controls TSH production.
When Medical Treatment Is Needed: Significantly abnormal TSH levels typically require medical intervention. Hypothyroidism is usually treated with synthetic thyroid hormone replacement (levothyroxine), which can effectively restore normal hormone levels and relieve symptoms.
Hyperthyroidism treatments vary depending on the cause and may include anti-thyroid medications, radioactive iodine therapy, or surgery. Your doctor will determine the most appropriate treatment based on your specific condition, age, and overall health.
What Influences Your TSH Levels
Factors That Can Raise TSH: Several conditions and factors can elevate your TSH levels: Hashimoto's thyroiditis (an autoimmune condition), iodine deficiency, certain medications (lithium, amiodarone, some psychiatric drugs), thyroid surgery or radioactive iodine treatment, pituitary disorders, severe illness or stress, and genetic factors affecting thyroid function.
Factors That Can Lower TSH: Various conditions can suppress TSH production: Graves' disease (an autoimmune condition), thyroiditis (inflammation of the thyroid), certain medications, pregnancy, and pituitary gland disorders.
Severe dieting, extreme stress, and certain supplements can also temporarily affect TSH levels
Managing Your TSH Levels
Supporting Healthy Thyroid Function: Whilst you cannot directly control your TSH levels, you can support optimal thyroid function through lifestyle choices. Ensure adequate iodine intake (sources include iodised salt, seafood, and dairy products) but avoid excessive amounts. Include selenium-rich foods like Brazil nuts, which support thyroid hormone production.
Manage stress through regular exercise, adequate sleep (7-9 hours nightly), and stress-reduction techniques like meditation or yoga. Chronic stress can disrupt the delicate hormone balance that controls TSH production.
When Medical Treatment Is Needed: Significantly abnormal TSH levels typically require medical intervention. Hypothyroidism is usually treated with synthetic thyroid hormone replacement (levothyroxine), which can effectively restore normal hormone levels and relieve symptoms.
Hyperthyroidism treatments vary depending on the cause and may include anti-thyroid medications, radioactive iodine therapy, or surgery. Your doctor will determine the most appropriate treatment based on your specific condition, age, and overall health.
Understanding Your Results
TSH levels are measured in milliunits per litre (mU/L):
Low: ≤ 0.35 mU/L
Normal: 0.351-5.5 mU/L
High: >5.5 mU/L
However, TSH interpretation isn't always straightforward. Your doctor will consider your symptoms, medical history, and other thyroid function tests (like free T4 and free T3) for a complete picture.
TSH levels can fluctuate throughout the day and may be affected by recent illness, stress, or certain medications. Your doctor may recommend retesting to confirm results or monitor treatment effectiveness. After thyroid dose changes, TSH levels are usually rechecked 2-3 months later.
Understanding Your Results
TSH levels are measured in milliunits per litre (mU/L):
Low: ≤ 0.35 mU/L
Normal: 0.351-5.5 mU/L
High: >5.5 mU/L
However, TSH interpretation isn't always straightforward. Your doctor will consider your symptoms, medical history, and other thyroid function tests (like free T4 and free T3) for a complete picture.
TSH levels can fluctuate throughout the day and may be affected by recent illness, stress, or certain medications. Your doctor may recommend retesting to confirm results or monitor treatment effectiveness. After thyroid dose changes, TSH levels are usually rechecked 2-3 months later.
Understanding Your Results
TSH levels are measured in milliunits per litre (mU/L):
Low: ≤ 0.35 mU/L
Normal: 0.351-5.5 mU/L
High: >5.5 mU/L
However, TSH interpretation isn't always straightforward. Your doctor will consider your symptoms, medical history, and other thyroid function tests (like free T4 and free T3) for a complete picture.
TSH levels can fluctuate throughout the day and may be affected by recent illness, stress, or certain medications. Your doctor may recommend retesting to confirm results or monitor treatment effectiveness. After thyroid dose changes, TSH levels are usually rechecked 2-3 months later.
The Takeaway
TSH is your thyroid's master controller, and abnormal levels serve as an early warning system for thyroid dysfunction. Because thyroid hormones affect virtually every body system, understanding your TSH levels is crucial for identifying potential thyroid problems before they significantly impact your health.
High TSH levels signal hypothyroidism, which can leave you feeling sluggish and unwell, whilst low TSH levels indicate hyperthyroidism, which can cause your body to race out of control. Both conditions are highly treatable when properly diagnosed and managed.
If you're experiencing symptoms of thyroid dysfunction, don't ignore them—early detection and treatment can prevent complications and dramatically improve your quality of life. Regular monitoring of TSH levels, especially if you have risk factors or a family history of thyroid disease, can help catch problems early.
The Takeaway
TSH is your thyroid's master controller, and abnormal levels serve as an early warning system for thyroid dysfunction. Because thyroid hormones affect virtually every body system, understanding your TSH levels is crucial for identifying potential thyroid problems before they significantly impact your health.
High TSH levels signal hypothyroidism, which can leave you feeling sluggish and unwell, whilst low TSH levels indicate hyperthyroidism, which can cause your body to race out of control. Both conditions are highly treatable when properly diagnosed and managed.
If you're experiencing symptoms of thyroid dysfunction, don't ignore them—early detection and treatment can prevent complications and dramatically improve your quality of life. Regular monitoring of TSH levels, especially if you have risk factors or a family history of thyroid disease, can help catch problems early.
The Takeaway
TSH is your thyroid's master controller, and abnormal levels serve as an early warning system for thyroid dysfunction. Because thyroid hormones affect virtually every body system, understanding your TSH levels is crucial for identifying potential thyroid problems before they significantly impact your health.
High TSH levels signal hypothyroidism, which can leave you feeling sluggish and unwell, whilst low TSH levels indicate hyperthyroidism, which can cause your body to race out of control. Both conditions are highly treatable when properly diagnosed and managed.
If you're experiencing symptoms of thyroid dysfunction, don't ignore them—early detection and treatment can prevent complications and dramatically improve your quality of life. Regular monitoring of TSH levels, especially if you have risk factors or a family history of thyroid disease, can help catch problems early.
References
British Thyroid Foundation. (2023). Understanding thyroid function tests: TSH and beyond. Clinical guidance for healthcare professionals.
National Institute for Health and Care Excellence. (2023). Thyroid disease: assessment and management. NICE guideline [NG145].
Garber, J. R., Cobin, R. H., Gharib, H., et al. (2012). Clinical practice guidelines for hypothyroidism in adults. Thyroid, 22(12), 1200-1235.
Ross, D. S., Burch, H. B., Cooper, D. S., et al. (2016). 2016 American Thyroid Association guidelines for diagnosis and management of hyperthyroidism and other causes of thyrotoxicosis. Thyroid, 26(10), 1343-1421.
References
British Thyroid Foundation. (2023). Understanding thyroid function tests: TSH and beyond. Clinical guidance for healthcare professionals.
National Institute for Health and Care Excellence. (2023). Thyroid disease: assessment and management. NICE guideline [NG145].
Garber, J. R., Cobin, R. H., Gharib, H., et al. (2012). Clinical practice guidelines for hypothyroidism in adults. Thyroid, 22(12), 1200-1235.
Ross, D. S., Burch, H. B., Cooper, D. S., et al. (2016). 2016 American Thyroid Association guidelines for diagnosis and management of hyperthyroidism and other causes of thyrotoxicosis. Thyroid, 26(10), 1343-1421.
References
British Thyroid Foundation. (2023). Understanding thyroid function tests: TSH and beyond. Clinical guidance for healthcare professionals.
National Institute for Health and Care Excellence. (2023). Thyroid disease: assessment and management. NICE guideline [NG145].
Garber, J. R., Cobin, R. H., Gharib, H., et al. (2012). Clinical practice guidelines for hypothyroidism in adults. Thyroid, 22(12), 1200-1235.
Ross, D. S., Burch, H. B., Cooper, D. S., et al. (2016). 2016 American Thyroid Association guidelines for diagnosis and management of hyperthyroidism and other causes of thyrotoxicosis. Thyroid, 26(10), 1343-1421.
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