The thyroid-stimulating hormone (TSH) exam measures the amount of TSH in the blood. The results convey how well a person'southward thyroid is performance.

Doctors tin use TSH test results to diagnose thyroid disorders, such as hypothyroidism and hyperthyroidism.

The pituitary gland produces TSH, which is a hormone that stimulates the thyroid gland.

The thyroid is a butterfly-shaped gland in the throat. It produces hormones that assist regulate many bodily functions, such equally metabolism, heart rate, and trunk temperature.

This article describes the TSH test and results. We also talk over what high and low TSH levels signal and available treatments.

An infographic guide showing the ranges of TSH levels. Share on Pinterest
MNT-infographic_guide infographic by Diego Sabogal 1401179-TSH-levels-original

The normal range depends on a person'due south historic period and whether they are pregnant.

The ranges tend to increase as a person gets older. Enquiry has not shown a consistent difference in TSH levels between males and females.

However, according to the American Thyroid Association, doctors generally consider levels are within a normal range between 0.iv–four.0 milliunits per liter (mU/l).

The following table provides estimates of TSH levels that are normal, low (indicating hyperthyroidism), and high (indicating hypothyroidism):

Many labs utilize these reference values.

However, there is some debate about these ranges. The author of a 2016 review suggests that normal levels are more likely to fall between 0.5–2.5 milli-international units (mIU) per milliliter.

Females are more probable to experience thyroid dysfunction than males. The Function on Women'due south Health reports that one in eight females feel thyroid bug at some point. This includes hyperthyroidism and hypothyroidism. The adventure of thyroid problems increases during pregnancy and around menopause.

Enquiry does not bear witness a consistent divergence in TSH levels betwixt males and females. Withal, some prove suggests that TSH levels are by and large college in females. For instance, studies in 2020 investigating Chinese and French populations suggest that TSH levels are higher in females, but other factors, such as age, are more probable to affect TSH levels.

In some people, thyroid atmospheric condition are linked with sexual dysfunction. This may affect more males than females. Co-ordinate to a 2019 study, 59–63% of males with hypothyroidism likewise experience sexual dysfunction, compared with 22–46% of females who have hypothyroidism.

Blood TSH levels tend to increase as people get older, with evidence noting that hypothyroidism is the most common thyroid status in people over 60 and steadily increases with age.

Inquiry involving older adults suggests that roughly seven–14% of people may have TSH levels to a higher place the upper limit of reference ranges.

Pregnancy hormones naturally increase the levels of sure thyroid hormones in the claret. This is essential for the development of the fetal encephalon and nervous organization.

At the same fourth dimension, the levels of TSH in the blood subtract. As a result, doctors utilize lower reference ranges during pregnancy. The lower TSH range is decreased past around 0.iv mU/50, and the upper limit reduced past approximately 0.5 mU/fifty.

Levels of TSH in the blood increase gradually during the 2nd and third trimesters, merely they remain lower than normal levels in women who are not significant.

Doctors carefully monitor TSH levels throughout pregnancy. Having unusually high or low levels can affect the run a risk of miscarriage and crusade pregnancy-related complications, such as:

  • preeclampsia
  • premature nativity
  • low birth weight
  • congestive heart failure

TSH levels are highest at birth and gradually subtract as a child gets older. As such, TSH levels can vary among children. After the newborn phase, health experts may define mild hypothyroidism in children equally TSH levels ranging between 4.v–10 mU/l.

The post-obit table shows TSH levels for children past historic period, according to an older study using data from 512 healthy children:

High TSH levels indicate hypothyroidism. People develop hypothyroidism when their thyroid produces low levels of hormones.

When someone's thyroid gland does not produce plenty hormones, the pituitary gland produces more than TSH to recoup.

Symptoms of hypothyroidism may include:

  • fatigue
  • weight gain
  • swelling of the face and cervix
  • increased sensitivity to common cold temperatures
  • dry skin
  • thinning pilus
  • a slow heart rate
  • irregular or heavy menstrual periods
  • fertility problems
  • depression
  • constipation

Low TSH levels indicate hyperthyroidism. This is as well known as an overactive thyroid.

If a person'due south thyroid gland is secreting levels of hormones that are likewise loftier, the pituitary gland produces less TSH.

Symptoms of hyperthyroidism can include:

  • irregular or rapid heartbeat
  • muscle weakness
  • nervousness or irritability
  • difficulty sleeping
  • frequent bowel movements or diarrhea
  • weight loss
  • mood changes

The TSH test involves a healthcare professional drawing blood from a vein in the inner arm. They then send the blood sample for laboratory testing.

Normally, people do not need to prepare for a TSH test. Withal, if the doc is checking the blood for more than 1 issue, a person may need to fast or prepare in another way. The doctor will provide this information beforehand.

A TSH examination is often the best way to monitor thyroid part. However, if a person has abnormally high or low TSH levels, the doctor may need to perform at least one other diagnostic test to identify the underlying cause. These tests look at levels of specific thyroid hormones and antibodies.

In add-on to age, sex, and pregnancy, many other factors can also affect TSH levels. Evidence suggests that genetic, ecology, or intrinsic factors can change TSH levels. Some of these factors may include:

  • other conditions occurring at the same time
  • medications
  • supplements
  • ethnicity
  • nutrition and iodine status
  • time of 24-hour interval and fourth dimension of yr
  • autoantibodies and heterophilic antibodies
  • smoking
  • pollutants

Doctors can treat hypothyroidism with medications, such as levothyroxine, that replace the missing thyroid hormones.

A person should accept this medication once a twenty-four hours or equally prescribed. The physician will monitor how well the handling is working by running additional blood tests every few months.

Co-ordinate to the Food and Drug Administration (FDA), people should accept levothyroxine once a solar day: in the morning and on an empty stomach, at to the lowest degree one-half an hour earlier eating.

The FDA besides recommends that a person informs their doc if they eat soybean flour, walnuts, dietary fiber, or cottonseed meal — these foods can touch how the body processes levothyroxine. Drinking grapefruit juice may besides delay the absorption of levothyroxine.

Hyperthyroidism treatments focus on reducing thyroid hormone levels to preclude long-term health complications.

A person may need to take beta-blockers and antithyroid medications.

Another effective treatment is radioiodine therapy. This involves taking a capsule or liquid that contains radioactive iodine-131, which destroys cells that produce thyroid hormones. However, people who take radioiodine therapy may develop hypothyroidism in the futurity.

Surgical removal of the thyroid gland can treat astringent hyperthyroidism. Doctors oftentimes reserve this for individuals who cannot take showtime-line medications and severe cases of hyperthyroidism.

A TSH test measures the amount of the hormone in the blood. Doctors can utilise the results to diagnose thyroid weather condition, such every bit hypothyroidism and hyperthyroidism.

Normal TSH ranges can vary widely, depending on a person'south age, sex, and weight. Reference TSH ranges remain controversial, only for most people, the normal range falls betwixt 0.4 and 4.0 mU/l.

Having an overactive or underactive thyroid tin can crusade health problems that interfere with a person'southward daily life. During pregnancy, unusually high or low TSH levels tin can pb to complications.

A doctor can provide more information about the TSH exam and interpreting the results.