Thyroid-Stimulating Hormone (TSH)
How It Feels
The blood sample is taken from a vein in
your arm. An elastic band is wrapped around your upper arm. It may feel tight.
You may feel nothing at all from the needle, or you may feel a quick sting or
There is very little chance of a problem from
having a blood sample taken from a vein.
- You may get a small bruise at the site. You can
lower the chance of bruising by keeping pressure on the site for several
- In rare cases, the vein may become swollen after the blood
sample is taken. This problem is called phlebitis. A warm compress can be used
several times a day to treat this.
- Ongoing bleeding can be a
problem for people with bleeding disorders. Aspirin, warfarin (Coumadin), and
other blood-thinning medicines can make bleeding more likely. If you have
bleeding or clotting problems, or if you take blood-thinning medicine, tell
your doctor before your blood sample is taken.
hormone (TSH) blood test is used to check for
thyroid gland problems.
The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.
Results are usually available in 2 to 3 days.
Thyroid-stimulating hormone (TSH)1
0.4–4.2 microunits per milliliter (mcU/mL) or 0.4–4.2
milliunits per liter (mU/L)
0.7–6.4 mcU/mL or 0.7–6.4 mU/L
|Newborns ( 1-4 days):|
1–39 mcU/mL or 1–39 mU/L
A slightly high TSH value may not require treatment. The doctor will consider any symptoms you might have along with other test results to determine if treatment is needed.
High TSH levels may be caused
- An underactive thyroid (hypothyroidism).
Hashimoto's thyroiditis is the most common cause of
- A pituitary gland tumor that is making too
much TSH. This is uncommon.
- Not taking enough thyroid hormone
medicine for treatment of an underactive thyroid gland.
Low TSH levels may be caused by:
- An overactive thyroid gland (hyperthyroidism). Causes of hyperthyroidism include
Graves' disease, a type of
goiter (toxic multinodular goiter), or a noncancerous
(benign) tumor called a toxic nodule.
- Damage to the pituitary gland
that prevents it from making TSH (a condition called secondary
- Taking too much thyroid medicine for treatment of
an underactive thyroid gland.
- Pregnancy during the first