TSH

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Formal name: Thyroid-stimulating hormone; thyrotropin

At a Glance

Why Get Tested?

To screen for and diagnose thyroid disorders; to monitor treatment of hypothyroidism and hyperthyroidism

When to Get Tested?

For screening: newborns; there is currently no recommendation in Australia for routine screening of adults. For monitoring treatment: as directed by your doctor. Otherwise, as symptoms present.

Sample Required?

A blood sample drawn from a vein in the arm or from pricking the heel of an infant

Test Preparation Needed?

None

The Test Sample

What is being tested?

The test measures the amount of thyroid-stimulating hormone (TSH) in your blood. TSH is made by the pituitary gland located in your brain. TSH is the pituitary gland’s messenger — it tells the thyroid gland to start making thyroid hormone. There is a feedback system between the pituitary gland and the thyroid gland. If too much T3 and T4 are being produced by the thyroid then this causes negative feedback on the pituitary gland and less TSH is produced. If too little T3 and T4 are being produced then TSH production increases. In healthy people this system regulates itself perfectly. However in thyroid or pituitary diseases the system gets unbalanced and the resulting changes can help diagnose the problem. See the table in What does the test result mean?

How is the sample collected for testing?

A blood sample is obtained from a needle placed in a vein in your arm or from pricking the heel of an infant.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.

The Test

Common Questions

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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.