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TSH (Thyroid-stimulating hormone) Test
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Lab Tests

TSH (Thyroid-stimulating hormone) Test

A TSH test is a blood test that measures the level of thyroid-stimulating hormone to determine how well your thyroid gland is functioning.

What is a TSH test?

TSH (thyroid-stimulating hormone), also known as thyrotropin, is produced by the pituitary gland in your brain. It signals your thyroid gland—a butterfly-shaped organ in your neck—to produce thyroid hormones. These hormones control vital functions, including heart rate, weight, digestion, and mood. If your thyroid hormone levels are low, the pituitary gland produces more TSH to stimulate the thyroid; if levels are high, it produces little or no TSH.

What is it used for?

The TSH test helps determine if you have hyperthyroidism (too much thyroid hormone) or hypothyroidism (too little thyroid hormone). It is also used to monitor patients taking thyroid medication or those who have undergone thyroid treatment to ensure hormone levels remain in a healthy range.

Why do I need a TSH test?

You may need a TSH test if you exhibit symptoms of thyroid imbalance:

  • Hyperthyroidism symptoms: Weight loss, rapid heartbeat, nervousness, trouble sleeping, shaky hands, or heat sensitivity.
  • Hypothyroidism symptoms: Fatigue, weight gain, cold sensitivity, joint/muscle pain, dry skin, or depression.

The test may also be used to investigate lumps or nodules on the thyroid to check for cancer or other growths.

What do the results mean?

An abnormal TSH result indicates that your thyroid is not producing the correct amount of hormones, though the test does not identify the underlying cause. If results are abnormal, your provider may order additional tests, such as:

  • T4 thyroid hormone test
  • T3 thyroid hormone test
  • Thyroid antibodies test: Used to diagnose autoimmune disorders like Graves' disease (hyperthyroidism) or Hashimoto's disease (hypothyroidism).

Important Considerations

Several factors can affect TSH levels even if the thyroid is healthy, including serious non-thyroid illnesses, age (levels may be higher in those over 80), and pregnancy. Newborns are routinely screened for congenital hypothyroidism.

Frequently Asked Questions

Yes. Adequate iodine intake, regular exercise, managing stress, and avoiding smoking can support thyroid health. If you’re on thyroid medication, taking it consistently at the same time each day and monitoring for side effects can help keep TSH within target.
Most laboratories return TSH results within 1–3 business days. If your result is abnormal, your clinician will usually schedule a follow‑up within 2–4 weeks to discuss treatment options or additional testing.
high TSH usually indicates an underactive thyroid. Your provider may order free T4 and T3 hormone levels to confirm hypothyroidism, and thyroid antibody tests (anti‑TPO, anti‑thyroglobulin) to check for autoimmune disease such as Hashimoto’s. In some cases, an ultrasound or radioactive iodine uptake scan may be requested.
The procedure is generally safe; the main risk is a small bruise or discomfort at the needle site. Rarely, a fainting spell or infection can occur, but these are uncommon. Proper technique and a calm environment minimize complications.===
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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