TSH Test: What It Shows and What It Does Not
Quick answer: TSH is the hormone your pituitary gland makes to tell your thyroid how much hormone to produce. It is the usual first check of thyroid function. It shows whether thyroid levels seem off, not why.
About this test
A TSH test measures thyroid stimulating hormone in your blood. The pituitary gland in the brain makes TSH, and it signals the thyroid how much thyroid hormone to make.
Why is it ordered?
- Symptoms that can go along with too much thyroid hormone, such as weight loss, a fast heartbeat or feeling hot.
- Symptoms that can go along with too little, such as tiredness, weight gain, feeling cold or constipation.
- Checking the dose of thyroid medicine.
- Looking at hair thinning, periods or fertility together with other tests.
What results may show
- A higher TSH can suggest the thyroid is making too little hormone.
- A lower TSH can suggest the thyroid is making too much hormone.
- Rarely, an abnormal result points to a pituitary problem.
What this test may not show
- It does not show the cause of a thyroid problem. Free T4, free T3 and thyroid antibody tests are often added.
- Serious illness can briefly lower TSH, and levels differ in pregnancy and older age.
- Biotin supplements can change thyroid results. Stop biotin at least 72 hours before your draw.
- An abnormal result does not always mean treatment is needed.
How to prepare
- No special preparation is usually needed. Fasting may be needed only if other tests are drawn at the same time.
- Stop biotin and hair, skin and nail supplements at least 72 hours before your draw.
- Ask your prescriber about timing of thyroid medicine. Do not stop a medicine without asking.
Where you can get this test
| Option | Price | Includes |
|---|---|---|
| Thyroid Function Test (TSH and Free T4) | $60 | TSH and free T4 |
| Comprehensive Thyroid Panel | $119 | TSH, free T4, free T3, TPO antibodies, thyroglobulin antibodies |
| Female Hormone Panel | $189 | FSH, LH, estradiol, progesterone, prolactin, TSH, testosterone |
| Menopause Panel | $149 | FSH, LH, TSH, progesterone, estradiol |
| Wellness Panel | $149 | CBC, CMP, lipid panel, vitamin D, A1c, hs-CRP, urinalysis, TSH |
| Comprehensive Health Panel, Women’s | $149 | CBC, CMP, lipid panel, vitamin D, A1c, hs-CRP, urinalysis, TSH |
| Comprehensive Health Panel, Man | $149 | CBC, CMP, lipid panel, total testosterone, A1c, hs-CRP, urinalysis, TSH |
| Hair Loss Panel | $199 | CBC, ferritin, iron and TIBC, TSH, free T4, vitamin D, total testosterone, DHEA-S |
A doctor’s visit is not required to order. Order online, then visit our Buffalo Grove or Lake Zurich location for the sample. Review results with your own healthcare provider.
Related tests
- Free T4: Free T4 measures the active form of the main hormone your thyroid makes.
- DHEA-S: DHEA-S is a hormone made mostly by the adrenal glands that the body uses to make testosterone and estrogen.
- Browse the full Lab Test Library
Frequently asked questions
What does a high TSH mean?
It often goes along with an underactive thyroid, but it needs to be read with free T4 and your symptoms.
What does a low TSH mean?
It often goes along with an overactive thyroid, but other causes exist. Review it with your provider.
Does biotin affect TSH?
Yes. Biotin can change thyroid test results. Stop it at least 72 hours before your draw.
Is TSH alone enough?
Often not. Free T4 is usually added to give a fuller picture.
Sources
Medically reviewed by Rodion Levin, FNP-C, Founder and Medical Director. This page is for general education. It does not diagnose a condition or replace advice from your healthcare provider.
