TSH Levels: Low to High Test Score Analysis

It ‘s important to understand the think of of both high thyroid-stimulating hormone ( TSH ) and low TSH. This applies whether you ‘re living with thyroid disease or having your beginning thyroid test .

TSH examination results can be confusing. A high TSH tied points to hypothyroidism ( hypoactive thyroid ). A humble TSH might mean hyperthyroidism ( hyperactive thyroid ). But there are exceptions to these interpretations, ampere well as what a “ normal ” grade means for you .

This article covers the causes of both high and low TSH levels along with several reasons TSH levels may change. You will besides learn about testing for a thyroid disorder and a number factors that may impact your results .

What Is TSH ?

TSH is a hormone that acts as a messenger to the thyroid gland gland. When released by the pituitary gland—a little gland at the base of the brain—TSH stimulates the thyroid to produce more thyroid hormone .

A high TSH suggests your thyroid is hypoactive ( hypothyroid ) and not doing its subcontract of producing adequate thyroid hormone .

A gloomy TSH suggests your thyroid gland is hyperactive ( hyperthyroid ) and producing excess thyroid hormone .

How thyrotropin Levels Change

thyrotropin levels seem counterintuitive. Why does a high TSH mean you have an hypoactive thyroid gland ? And why do low levels mean it ‘s hyperactive ?

To answer that, you have to know that TSH and thyroid gland hormones are different things. The thyroid hormones are :

Your body uses thyroid gland hormones to regulate all kinds of processes. That includes how fast you burn calories, your kernel rate, and many other automatic functions .

When thyroid gland hormones are depleted, your pituitary makes more TSH. That signals the thyroid to increase product. When levels are high, the pituitary releases less TSH. That signals the thyroid to slow down. This is why high TSH indicates low thyroid gland function and vice versa .

Interpreting TSH Levels

high and low tsh levels
Verywell / Emily Roberts
Understanding when and why thyroid hormone is released ( or not ) helps clear up what a low TSH and a eminent TSH level reveal about your thyroid gland ‘s function .

TSH is measured in mU/L. This abbreviation stands for milliunits per liter, with one milliunit equating to one-thousandth of a unit .

The normal range for TSH is generally between 0.5 mU/L and 5.0 mU/L.As with most medical conditions and tests, however, there are exceptions to this rule .

Thyroid hormone levels that are considered normal may be abnormal for you under certain conditions. It ‘s for this reason that healthcare providers have varied opinions about what the optimum TSH level should be .

controversy Over Optimal TSH

While most laboratories define a convention TSH as between approximately 0.5 mU/L and 5.0 mU/L, some experts argue that the upper specify of a normal TSH should be lower—around 2.5 mU/L .

The reason behind this is that the huge majority of adults without thyroid disease have a TSH value between 0.45 and 4.12 mU/L .

In addition, some healthcare providers believe older patients should have a TSH degree that is greater than 4.0 mU/L or 5.0 mU/L, since TSH normally increases with long time .

Healthcare providers can avoid some of this controversy simply by looking at each person as an individual. For case, a person who still has significant symptoms of hypothyroidism at a TSH of 4.0 mU/L may do better with a finish TSH of around 1.0 mU/L .

In contrast, person who has health risks—such as heart disease or osteoporosis—may benefit from having a finish TSH that is higher, possibly around 5.0 mU/L or 6.0 mU/L .

In pregnancy, TSH should not be allowed to rise above 2.4 mU/L in the inaugural tailored or 3.0 mU/L for the irregular and third base. That protects the health of both the baby and mother .


A normal TSH value is by and large defined as between 0.5 mU/L and 5.0 mU/L. But opinions about this change, since everyone has a personal “ normal ” that depends on their senesce and overall health. For exemplar, your aim level may be higher if you have kernel disease or lower if you are meaning .

Causes of High TSH

A high TSH means unlike things depending on whether a person has known thyroid gland disease or not .

In People Without Known Thyroid Disease

A eminent TSH in people who are not undergo thyroid gland disease treatment normally indicates the presence of primary hypothyroidism .

This is by far the most coarse shape of hypothyroidism, and it occurs because the thyroid gland produces an inadequate amount of thyroid hormones. The pituitary gland senses these low levels and increases the product of TSH .

An lift thyrotropin may besides occur with normal thyroid function due to the presence of antibodies, proteins made by the immune organization .

In People Being Treated for Thyroid Disease

A high thyrotropin may be found in people being treated for either hypo- or hyperthyroidism .

With hypothyroidism, a high TSH normally means that the dose of thyroid hormone surrogate needs to be increased .

In some cases, however, the dose is okay, but the medication is not being amply absorbed. For exercise, many foods and medications can affect the assimilation of Synthroid ( levothyroxine ) in your system. Learning what to avoid while taking this medication is significant for it to work by rights .

With hyperthyroidism, a high TSH normally means that the treatment —be it surgery, radioactive tincture of iodine, or medications—was so effective in limiting the production of thyroid hormone that it caused the person to become hypothyroid .

Causes of Low TSH

A gloomy TSH often means that a person has an elevated level of thyroid hormones .

In People Without Known Thyroid Disease

low TSH is most frequently associated with hyperthyroidism. This can be due to a number of causes, ranging from autoimmune disease to lumps in the thyroid gland ( toxic nodules ) to an abnormally enlarged thyroid gland gland ( goiter ) .

It can besides occur during a normal pregnancy as thyroid hormones are affected by “ the pregnancy hormone ” human chorionic gonadotropin ( human chorionic gonadotropin ) .

Less frequently, a miss of TSH produced by the pituitary gland ( due to dysfunction ) can lead to abject levels of thyroid hormone in the blood—a discipline known as cardinal hypothyroidism. This is an exception to the cosmopolitan rule that hypothyroidism is associated with a senior high school TSH .

cardinal hypothyroidism is rare and normally associated with a lack of early pituitary hormones. This insufficiency leads to a issue of other symptoms as well .

In People With Thyroid Disease

In people being treated for hypothyroidism, a low TSH tied may mean :

  • Overmedication with thyroid hormone replacement
  • Interactions that cause increased absorption or activity despite an optimal dose of medication
  • Central hypothyroidism

In people being treated for hyperthyroidism, a low TSH tied normally means that far discussion is needed to reduce thyroid hormone levels .

It could besides mean that a person must continue to be monitored to make sure thyroid hormone levels return to convention. This is frequently the case for people who have irregular thyroiditis related to pregnancy or chemotherapy discussion .

hypoactive Thyroid + High Thyroid

  • treatment may need to be more aggressive
  • medication may not be absorbing enough

hypoactive Thyroid + Low TSH

  • treatment may be more aggressive than needed
  • medicine may be absorbing besides much

Factors That Can Skew TSH Results

There are a number of factors that can affect TSH levels. These are important to consider because lab values do n’t tell the whole story about person ‘s condition .

A treatment plan that does not besides consider person ‘s symptoms may prove to be ineffective .

testing ground erroneousness

If a TSH screen consequence is unexpected, simply repeating the test is frequently the best course of action .

Errors can occur during the blood draw, in transcribing the results, or due to mix-ups in the lab. statistically, there is constantly a gamble of lab error, and results should always be interpreted along with clinical symptoms and findings .


Antibodies are thought to interfere with accurate thyroid testing in roughly 1 % of people .

In a 2018 review, such intervention caused either misdiagnosis or inappropriate treatment in more than 50 % of people who have these antibodies :

  • Heterophile antibodies: People exposed to animal-derived drugs and antibody therapies typically have these. A discrepancy between TSH levels and free T4, or between TSH levels and your symptoms, should alert your healthcare provider of a test inaccuracy.
  • Thyroid antibodies: These may also affect TSH levels in people who may or may not have a thyroid condition. Again, a discrepancy between lab values and your symptoms should raise the question of test inaccuracy.
  • Other antibodies: Anti-ruthenium and anti-streptavidin antibodies can also affect TSH testing results.

Health and Habits

A total of other factors can affect TSH quiz results, including :

  • The time of day that the test is done: If you are tested after fasting—for example, before you have eaten anything for the day—your TSH levels may be higher than if you had eaten just before your test.
  • Illness: Acute or chronic illnesses may put stress on your endocrine system, resulting in a skewed test result.
  • Pregnancy: TSH levels may be lower than the normal range during pregnancy, regardless of whether or not you have a thyroid disorder.
  • Medications: Some medications that are used to treat heart disease and cancer may affect results. Nonsteroidal anti-inflammatory medications, or NSAIDs, like Advil (ibuprofen) can as well.
  • Foods or supplements: Items rich in iodine or derived from kelp may interfere with testing. The same is true about biotin supplements.
  • Changes in sleep habits: A lack of quality sleep has been linked with thyroid imbalances.

Testing Method

A capillary feel goad test, or lineage spot quiz, is a reasonably controversial option to traditional TSH test .

It uses a finger prick quite than a criterion blood puff from your vein to evaluate thyroid function. Blood spotlight testing kits have besides been developed then that you can monitor your TSH level from home .

Proponents of this test believe that it ensures greater accuracy without requiring deoxyadenosine monophosphate much of a sample distribution as a venous blood describe .

however, since the test is not widely available right nowadays, it ‘s unknown precisely how well the test compares with conventional TSH screen .


No lab test is 100 % accurate, including the TSH test. Do your depart to help get the most accurate results by being angstrom coherent as possible when it comes to the conditions under which you are tested. For model, always have your test done at the like time of day, postpone your appointment if you are ghastly, and be certain you ‘re always getting quality sleep.

When TSH Alone Is not adequate

During diagnosis, most healthcare providers use the TSH test to evaluate thyroid serve and determine the optimum naturally of treatment. There are times, however, when knowing one ‘s TSH may be insufficient .

For example, free T4 in addition to TSH is normally tested if a healthcare supplier suspects thyroid dysfunction due to disease of the pituitary gland or hypothalamus .

similarly, if the TSH is normal, but a person however has symptoms of being hyperthyroid or hypothyroid, dislodge T4 may be checked .

TSH is besides not necessarily sufficient to monitor hypothyroidism during pregnancy ; T4 and release T4 are often recommended .

Depending on the clinical position, other thyroid tests that may be done include ( T3 ), unblock T3, invert T3, and thyroid antibody tests .


A TSH level that is optimum for all people can not quite be established. That ‘s because TSH levels vary depending on numerous factors, including your old age, your thyroid condition, and possibly even how well you sleep at night or when you last eat .

To gauge the optimum level for you, your healthcare supplier should consider these factors along with any symptoms you are experiencing .

You can besides improve the accuracy of your tests by keeping any factors that may influence your results adenine consistent as potential .


5 Common Misconceptions About Thyroid Disease

A Word From Verywell

The TSH test is the gold standard in diagnosing and monitoring thyroid disease. But as with any aesculapian examination, there are exceptions to what the test results may mean, adenine well as situations in which the test may be inaccurate .

It is wholly potential that you may inactive have symptoms despite a normal TSH level. If this is the lawsuit, speak up. even a “ normal ” thyrotropin may be abnormal for you .

And if you do n’t feel you ‘re being heard, consider seeking a second impression .

Frequently Asked Questions

  • What is the normal range for TSH levels?

    The normal compass for TSH is between 0.5 mU/L and 5.0 mU/L .

  • What does it mean when your TSH levels are low?

    A broken TSH level—below 0.5 mU/L—indicates an hyperactive thyroid, besides known as hyperthyroidism. This means your body is producing an overindulgence total of thyroid gland hormone .

  • What causes high TSH levels?

    A high TSH level—above 5.0 mU/L—indicates an hypoactive thyroid, besides known as hypothyroidism. This means your consistency is not producing enough thyroid hormone .

  • How does estrogen affect TSH levels?

    abject estrogen impairs the thyroid gland ‘s ability to make thyroid hormones. thus thyrotropin rises to get the thyroid to produce more. high estrogen leads to increased thyroid hormone production and lower TSH. In menopause, estrogen levels are lower, which sometimes triggers thyroid gland disease .
    Learn More :
    Thyroid Disease and Menopause : What ‘s the Link ?

  • Do diet changes level out TSH?

    They can, yes. Studies show that dietary changes can have a beneficial effect on TSH and thyroid function. While a diet designed specifically for you is best, some researchers have seen success with a Mediterranean-style diet .
    Learn More :
    nutrition and Your Thyroid Health

reservoir : https://nutritionline.net
Category : Healthy