Thyroid
TSH (Thyroid-Stimulating Hormone)
Thyroid
Primary thyroid screening test. Elevated in hypothyroidism, low in hyperthyroidism.
VAT-exempt medical service
Thyroid-stimulating hormone (TSH) is produced by the pituitary gland and acts as the master regulator of thyroid activity. It signals the thyroid gland to release thyroxine (T4) and triiodothyronine (T3), which control metabolism, energy use, and body temperature. Because TSH responds sensitively to even small shifts in thyroid hormone levels, it is the single most informative first-line test for evaluating thyroid health.
A TSH test is recommended as part of routine health screening, when symptoms suggest thyroid imbalance, and for monitoring an existing thyroid condition or medication adjustment. It is also valuable during fertility evaluation in women, since thyroid dysfunction can impair ovulation and pregnancy outcomes. If you have recently changed thyroid medication dosage, wait six to eight weeks before retesting TSH to ensure an accurate reading.
What a high value can mean
Elevated TSH typically signals that the thyroid gland is underactive (hypothyroidism) and is not producing enough T4 and T3. The pituitary responds by increasing TSH output in an attempt to stimulate the thyroid. The most common underlying cause is Hashimoto's thyroiditis, an autoimmune condition. Stress, infections, and certain medications can also temporarily raise TSH. A full thyroid panel including Free T4, Free T3, and thyroid antibodies is recommended for a complete picture.
What a low value can mean
Low TSH usually indicates hyperthyroidism, where the thyroid is overproducing hormones and the pituitary reduces TSH output accordingly. Graves' disease, an autoimmune disorder, is the most frequent cause. In rare cases, low TSH combined with low T4 may point to a pituitary gland problem rather than a thyroid issue.
No advance preparation is required. Do not take thyroid medication until after the blood draw. Bring valid identification to your appointment. If you take a supplement containing biotin (often sold for hair and nails), pause it for two days before the test, as high doses can distort the result.
Order your test
Choose your test and pay online. Your lab referral is created straight away.
Give your sample
Visit any of our partner sampling locations. No appointment needed at most of them.
The lab analyses it
Your sample is analysed at an accredited Swedish laboratory.
Get your results
Your values appear in your account with reference ranges and an explanation of each marker.
Most laboratories cite a reference range of roughly 0.4-4.0 mU/L, though many endocrinologists consider an optimal level to be between 0.5 and 2.5 mU/L. Individual targets may differ based on age, pregnancy status, and clinical context.
Yes. Physical or emotional stress, acute illness, and sleep deprivation can temporarily elevate TSH. If your result is borderline, your doctor may recommend retesting after a few weeks.
While TSH is a good screening tool, it does not reveal the full picture. For a thorough assessment, combine TSH with Free T4, Free T3, and thyroid antibodies (TPO and TG antibodies).
If you are on stable thyroid medication, annual testing is usually sufficient. After a dosage change, wait six to eight weeks before retesting. More frequent monitoring may be needed during pregnancy.