TSH Normal Range By Age: Men, Women, In Pregnancy, And More

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HealthlineSubscribeTSH Reference Ranges by Age and During Pregnancy

Medically reviewed by Valinda Riggins Nwadike, MD, MPH — Written by Tim Jewell — Updated on October 3, 2025

Adults
Children
During pregnancy
Regulating TSH levels
Takeaway

Thyroid-stimulating hormones (TSH) help regulate your body’s production of thyroid hormone. High TSH levels mean your thyroid is underperforming, while low levels mean you’re producing too much.

Your pituitary gland produces thyroid-stimulating hormones (TSH), which help regulate the production of thyroid hormones.

TSH levels change inversely with how much thyroid hormone is in your body. If your pituitary gland produces more TSH, your thyroid will produce more hormones. The two glands work together to make sure the right amount of thyroid hormone is being produced.

High TSH levels usually mean that your thyroid is underperforming. Your pituitary gland reacts to a lack of thyroid hormones by producing extra TSH to make up the difference. This is called hypothyroidism.
Low TSH levels usually mean that you’re producing too much thyroid hormone. Your pituitary gland responds accordingly by decreasing TSH production to regulate thyroid function. This is called hyperthyroidism.

Doctors use TSH blood tests to assess whether your TSH levels are in the normal or targeted range.

The targeted range of TSH for an adult is 0.4 to 4.0 milli-international units per liter (mU/L). However, that range can vary according to your age, whether you’re pregnant, or whether you’re already being treated for a thyroid disorder.

If you’re taking thyroid hormone replacement medication, the targeted TSH range is 0.5 to 3.0 nU/L.

This article reviews the TSH reference ranges for different age groups and for pregnant people.

TSH reference ranges in adults

The estimated TSH reference ranges for adults based on age are as follows:

Age range	Targeted TSH ranges	Low TSH	High TSH
18 to 30 years	0.5 to 4.1 mU/L	< 0.5 mU/L	> 4.1 mU/L
31 to 50 years	0.5 to 4.1 mU/L	< 0.5 mU/L	> 4.1 mU/L
51 to 70 years	0.5 to 4.5 mU/L	< 0.5 mU/L	> 4.5 mU/L
71 to 90 years	0.4 to 5.2 mU/L	< 0.4 mU/L	> 5.2 mU/L

TSH reference ranges in children

TSH tends to be high for the first month after a child is born. As they approach adulthood, TSH levels gradually decrease before rising again as they age.

The TSH reference ranges in children based on their age are as follows:

Age	Targeted TSH ranges
at birth	3.84 to 11.75 mU/L
1 month	1.18 to 3.57 mU/L
1 years	1.17 to 3.55 mU/L
5 years	1.15 to 3.47 mU/L
12 years	1.09 to 3.31 mU/L
18 years	1.05 to 3.16 mU/L

TSH reference ranges during pregnancy

Pregnancy can significantly affect the thyroid gland and its function due to the body’s increased metabolic needs. For example, during pregnancy, a maternal body may require 40% to 100% more thyroid hormones to meet the needs of the mother and fetus.

Pregnant people without thyroid disease don’t usually need additional thyroid hormone supplements as their bodies naturally make more thyroid hormone during pregnancy to provide enough for themselves and their baby.

But if you are already being treated for hypothyroidism, you may need to increase your dose of thyroid hormone supplements. For this reason, it’s important to monitor TSH levels during your pregnancy:

as soon as you know you’re pregnant
every 4 to 6 weeks during pregnancy
2 to 4 weeks after pregnancy

The TSH reference ranges during pregnancy are as follows:

Stage of pregnancy	Targeted TSH ranges	Low TSH	High TSH
first trimester	0.6 to 3.4 mU/	< 0.6 mU/L	> 3.4 mU/L
second trimester	0.37–3.6 mU/L	< 0.37 mU/L	> 3.6 mU/L
third trimester	0.38–4.0 mU/L	< 0.38 mU/L	> 4.0 mU/L

If you are pregnant, let your doctor know about any thyroid disorders you have

If you have a preexisting thyroid disorder, be sure to let your doctor or obstetrician-gynecologist know. They can help you manage your condition during and after pregnancy.

How are abnormal TSH levels treated?

A doctor may recommend one or more of the following treatments for abnormal levels of TSH:

Hypothyroidism (high TSH)

daily thyroid hormone medications, such as levothyroxine
natural thyroxine hormone extracts and supplements
consuming less of substances that affect levothyroxine absorption, such as fiber, soy, iron, or calcium

Hyperthyroidism (low TSH)

oral radioactive iodine to shrink your thyroid gland
methimazole or propylthiouracil to keep your thyroid from making too much thyroid hormone
removal of your thyroid gland if regular treatments don’t work or may be threatening to your health, such as during pregnancy

The takeaway

Abnormal TSH levels can indicate that your thyroid gland isn’t functioning properly. This can lead to long-term complications if you have an underlying condition such as hypo- or hyperthyroidism.

If you have a family history of thyroid disorders or have had abnormal TSH levels on previous test results, make sure you get your TSH levels tested regularly.

Follow any instructions your doctor provides, such as stopping certain medications or avoiding specific foods before a TSH test, to ensure accurate results.

How we reviewed this article:

SourcesHistoryHealthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical journals and associations. We only use quality, credible sources to ensure content accuracy and integrity. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.

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Medically reviewed by Valinda Riggins Nwadike, MD, MPH — Written by Tim Jewell — Updated on October 3, 2025

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