Explanation

TSH: what is measured?

TSH (thyroid-stimulating hormone) is made by the pituitary gland and prompts the thyroid to produce thyroid hormone. If the thyroid is underactive, TSH rises; if it is overactive, TSH falls. This makes TSH the most sensitive single measurement of thyroid function.

What can it detect?

Underactive thyroid (hypothyroidism), including at an early stage without symptoms
Overactive thyroid (hyperthyroidism)

Result

What does the result mean?

TSH too high

A raised TSH usually fits an underactive thyroid. The pituitary gland then makes extra TSH to stimulate the thyroid. A slightly raised value with a normal free T4 is called subclinical hypothyroidism; it often causes no symptoms and sometimes resolves on its own. Symptoms that may go with it: tiredness, feeling cold, weight gain, slowness, dry skin.

TSH too low

A low TSH usually fits an overactive thyroid, or taking too high a dose of thyroid medication. Symptoms that may go with it: restlessness, palpitations, weight loss, trembling, feeling hot. A slightly low value can also be temporary, for example during or after another illness.

After an abnormal result

The GP usually has free T4 measured and repeats the TSH after a few weeks before making a diagnosis or starting treatment.

Reliability

How reliable is the test?

According to the Dutch GP guideline (NHG), TSH is the first and most sensitive test when a thyroid disorder is suspected. A normal TSH virtually rules out a thyroid disorder; an abnormal TSH is not a diagnosis on its own. The GP then has free T4 (and sometimes antibodies) measured and repeats the test after a few weeks, because TSH can be temporarily abnormal.

What can affect the result?

TSH can be temporarily disturbed by another illness, after a pregnancy, by medicines (including biotin, amiodarone, lithium and corticosteroids) and in the first months after starting or adjusting thyroid medication.
The value follows a daily rhythm and is highest at night and early in the morning.
In a rare disorder of the pituitary gland itself, TSH can be normal while the thyroid is still underactive.

Preparation

Do you take biotin (vitamin B8, often in hair and nail supplements)? Stop at least 2 days before the sample is taken, or 4 days for a high dose.

Who it is for

Who is the test useful for?

Useful for

Useful with symptoms that fit a thyroid disorder (tiredness, weight change, feeling cold or hot, palpitations, mood symptoms), with thyroid conditions in the family, with a known autoimmune disease or after radiotherapy of the neck. Also for monitoring thyroid medication. In adults without symptoms or risk factors, an abnormal result is often a mild or temporary change that needs no treatment.

How common is it?

An underactive thyroid affects about 3 to 4 in 100 adults in the Netherlands, more often women and older people. An overactive thyroid is less common, about 1 in 100. Subclinical abnormalities (only TSH abnormal) are even more common and by no means always have consequences.

NIVEL primary care registrations and the NHG guideline on thyroid disorders

Drawbacks and risks

A slightly abnormal TSH is often temporary; without a repeat measurement this can lead to unnecessary worry or unnecessary treatment.

Get tested

TSH: test panels

TSH is part of these test panels. You order online and have your blood drawn at a collection point or collect the sample at home.

Blood draw
TSH
TSH; primary screening of thyroid function.
€ 23,00
Blood draw
TSH and Free T4
TSH and free T4; for thyroid function assessment.
€ 41,00
Blood draw
Thyroid Test (TSH, Free T4, FT3)
TSH plus free T4 and FT3 for assessment of thyroid function.
€ 60,00
Blood draw
Hair Loss Test
Panel for hair loss; Vitamin B12, Iron, Ferritin, TSH, Cortisol, and DHT.
€ 141,00
Blood draw
General Health Checkup
With this General Health Check-up, you gain detailed insight into your overall health and well-being.
€ 125,00
Fingerstick
Thyroid Panel: TSH, Free T4, and FT3
Combination of TSH, free T4, and FT3.
€ 60,00
Fingerstick
TSH
TSH; for thyroid function and therapy monitoring.
€ 23,00
Blood draw
InsideTracker
InsideTracker Blood Analysis: analyze 48 biomarkers for complete health optimization and personalized recommendations.
€ 335,00
Blood draw
Hormone Recovery (After Steroids)
Testosterone, free testosterone, SHBG, LH, FSH, estradiol, TSH, liver function, and lipid profile. For recovery after anabolic steroid use.
€ 325,00

Evidence

Sources

This explanation is based on Dutch guidelines and independent information. It is general information, not a diagnosis. Discuss an abnormal result with your GP.

More about risks and results

More explanations

Other tests: Thyroid

All tests

TSH

TSH: what is measured?

What can it detect?

What does the result mean?

TSH too high

TSH too low

After an abnormal result

How reliable is the test?

What can affect the result?

Preparation

Who is the test useful for?

Useful for

How common is it?

Drawbacks and risks

TSH: test panels

TSH

TSH and Free T4

Thyroid Test (TSH, Free T4, FT3)

Hair Loss Test

General Health Checkup

Thyroid Panel: TSH, Free T4, and FT3

TSH

InsideTracker

Hormone Recovery (After Steroids)

Sources

Other tests: Thyroid

TSH

TSH: what is measured?

What can it detect?

What does the result mean?

TSH too high

TSH too low

After an abnormal result

How reliable is the test?

What can affect the result?

Preparation

Who is the test useful for?

Useful for

How common is it?

Drawbacks and risks

TSH: test panels

TSH

TSH and Free T4

Thyroid Test (TSH, Free T4, FT3)

Hair Loss Test

General Health Checkup

Thyroid Panel: TSH, Free T4, and FT3

TSH

InsideTracker

Hormone Recovery (After Steroids)

Sources

Other tests: Thyroid