TSH is your brain’s signal to the thyroid, helping spot under- or overactive thyroid function.
Thyroid-stimulating hormone (TSH) is made by your pituitary gland and tells your thyroid how much thyroid hormone to produce. It is the main screening test for thyroid function.
TSH works on a feedback loop. When thyroid hormone is low, TSH rises to push the thyroid harder. When thyroid hormone is high, TSH falls.
A high TSH usually means an underactive thyroid (hypothyroidism), where the gland is not making enough hormone. This can cause tiredness, weight gain, feeling cold, and low mood.
A low TSH usually means an overactive thyroid (hyperthyroidism), which can cause a fast heartbeat, weight loss, anxiety, and trouble sleeping. Because TSH is so sensitive, it often changes before symptoms appear.
Aniva reads your result against research-backed ranges, not just the lab's wide normal. The reference shown below is specific to this biomarker.
| Group | Serum TSH (SI) |
| Adults (general) | ~0.4 to 4.0 mIU/L |
| Note | upper limit tends to rise with age |
Ranges are guidance only and vary by lab, assay, age, and pregnancy. Many labs use a slightly narrower adult interval. Read your result against your own lab's reference, in line with DGKL practice.
TSH varies a little through the day and is often slightly higher in the early morning. Acute illness, pregnancy, biotin supplements, and some medicines such as steroids, lithium, and amiodarone can shift results. Biotin in particular can cause false readings, so pause it before testing.
Usually read with free T4, and free T3 or thyroid antibodies (TPO) when a thyroid disorder is suspected.
What does a high or low TSH mean? High TSH often points toward an underactive thyroid. Low TSH often points toward an overactive thyroid or overtreatment.
Do I need to fast for this test? No. You can test TSH without fasting. Try to test at a similar time of day.
What can affect my TSH result? Thyroid medicines, steroids, dopamine-like drugs, biotin supplements, illness, and pregnancy can shift results. Tell your clinician about all meds and supplements.
How often should I test TSH? If stable on treatment, many people test every 6 to 12 months. After a dose change, recheck in about 6 weeks.
How long do results take? Results are usually ready in about 7 days.
What should I discuss with my clinician? Share symptoms, medications, supplements, and pregnancy plans. Ask if you also need Free T4, Free T3, or thyroid antibodies.
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