A patient seated in the chair before a blood draw
In person

TSH

The pituitary’s signal to your thyroid, from one blood draw.

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  • 2,000+ lab locations. Find one near you
  • Nothing due at the lab. FSA / HSA accepted
  • Ordered by a licensed clinician

At a glance

Collection
Blood draw
A standard blood draw at the lab.
Preparation
None
No fasting. If you have had fluorescein angiography, wait 3 days.
Results
1 to 3 days
Typical turnaround after your visit.
Where
2,000+ lab locations
Nationwide, with nothing due at the lab.

About this test

TSH (thyroid-stimulating hormone) is made by the pituitary gland and tells the thyroid how much hormone to make. It moves opposite to thyroid hormone: TSH tends to rise when thyroid hormone is low and fall when it is high. No fasting is needed, but wait at least 3 days after fluorescein angiography.

For adults 18 and older. Test availability varies by lab location.

Who should take this test?

Adults often check TSH as part of routine care, with a family history of thyroid conditions, or to follow up on a past result. Commonly related symptoms include:

Body

  • Tiredness
  • Feeling cold or too warm

Weight

  • Unexplained weight change

Hair

  • Hair thinning

Skin

  • Dry skin

Neck / thyroid

  • Swelling in the neck

Ask about this test

Not sure this is the right test?

AI-generated. For information only, not medical advice. Call 911 for an emergency.

What does this test measure?

Your result shows how strongly your pituitary is signaling your thyroid, which can help a healthcare provider see whether your thyroid may be underactive or overactive.

Thyroid-stimulating hormone (TSH)
TSH is made by the pituitary gland at the base of your brain and tells your thyroid how much hormone to make. It usually moves in the opposite direction from thyroid hormone: TSH tends to rise when the thyroid is underactive and fall when it is overactive. It is the usual first thyroid check.
Why it’s measured: Shows how strongly your pituitary gland is signaling your thyroid to work.

How it works

  1. Step 1

    Order online

    Check out here. A licensed clinician in your state reviews your order and sends it to the lab.

  2. Step 2

    Visit a lab

    Bring a photo ID to any of 2,000+ lab locations. No fasting. If you have had fluorescein angiography, wait 3 days. Nothing is due at the lab.

  3. Step 3

    Get your results

    Results post to your account, usually in 1 to 3 days, each number next to the lab’s reference range.

Find a lab near you

Choose from 2,000+ lab locations nationwide. Your order works at any of them.

What your results tell you

TSH is reported in milli-international units per liter (mIU/L) and shown next to the lab’s reference range for comparison.

  • Your number next to the lab’s reference range
  • Explained in plain language
  • A licensed clinician reviews your order and, if appropriate, orders the test.
  • A lab report you can download and share

A TSH outside the range is often followed by Free T4. A healthcare provider can explain your result; don’t change thyroid medicine based on it alone.

TSH, TSH with reflex, or a thyroid panel?

Three ways to start a thyroid check.

TSH

The pituitary’s signal to the thyroid, measured by itself.

What the lab runs
TSH by itself
If TSH is out of range
Any follow-up test is a separate request
Useful for
A first look or a routine recheck

Clinical-grade testing, from the comfort of home.

From the lab to your report, every step of our process meets the gold standard in medical testing.

  • CLIA-certified labs

    Every lab we partner with is certified under the Clinical Laboratory Improvement Amendments, meeting both state and federal standards with regular independent inspections.

  • We protect your health data

    We protect your health data with encryption and do not sell it. Some results must be reported to public health authorities by law. See our Privacy Notice.

  • Rigorous quality assurance

    All partner labs run regular internal quality checks, participate in proficiency testing, and comply with federal and state lab regulations.

  • Clinician-reviewed reports

    Results are reviewed by an independent, licensed clinician.

Questions

Common questions.

Anything else, our care team answers by phone, text, or email.

The pituitary responds to thyroid hormone levels. When they drop, it makes more TSH to push the thyroid to work harder. When they are high, it makes less. So a high TSH often goes with an underactive thyroid, and a low TSH with an overactive one.

A healthcare provider usually reads TSH with Free T4 for more context.

Yes. Fluorescein is a dye used in some eye exams, called fluorescein angiography. It can make TSH read falsely low, so the draw should wait at least 3 days after that exam, or 2 weeks for people on dialysis.

If you’ve had one recently, tell the healthcare provider who reads your results. Don’t stop or change any medicine or supplement without talking with your healthcare provider.

TSH is one of the tests prescribers use to follow thyroid medicine. Share your result with your prescriber, and don’t change your dose based on this result alone. Your prescriber decides when to recheck and whether anything needs to change.

TSH shows the signal, not the thyroid hormone itself, and it doesn’t show the cause of a high or low result, such as an autoimmune condition.

TSH works as a thyroid check when a pituitary condition isn’t suspected, since pituitary conditions can change TSH on their own. A healthcare provider may suggest Free T4 or antibody tests to learn more.

Lab tests are informational and don’t diagnose conditions on their own. Available to adults 18 and older; test availability varies by lab location. A licensed clinician reviews your order and, if appropriate, orders the test. All testing is performed at CLIA-certified laboratories. Not for emergencies: if you think you may be having a medical emergency, call 911.