TSH receptor antibodies
TRAb · TSH receptor antibody test · TSI test · Graves disease blood test
This blood test looks for special antibodies that can make your thyroid work too hard.
When your thyroid hormones are high and the cause is not clear. Also to check treatment, and in pregnancy if you have had thyroid problems before.
⏱ Duration: the blood draw takes a few minutes; results usually come in 1 to 5 days
Be sure to tell your doctor
How to prepare
- Timing. Morning is best. Many labs advise coming on an empty stomach. Check ahead.
- Biotin. If you take biotin, ask your doctor how many days before the test to stop it.
- Medicines. Do not stop anything on your own. Tell your doctor what you take. They will decide if anything needs to change before the test.
- Clothing. A sleeve you can easily roll up above the elbow.
What to bring
- Your referral or list of tests
- Your ID
- Past thyroid hormone results
- Your thyroid ultrasound report, if you have one
How it goes
- You sit down and rest your arm on the armrest
- A band is tied above your elbow, and you are asked to clench your fist a few times
- The skin is wiped with antiseptic
- A quick prick. Blood fills the tubes in a few seconds
- The needle comes out, and a cotton pad is pressed on the spot
What you'll feel
- A quick prick, like a pinch
- Sometimes slight dizziness. Tell the nurse, and they will help you lie down
Afterwards
- Press the cotton pad for 3 to 5 minutes
- You can eat right away and go back to your usual day
- An endocrinologist, a hormone doctor, will explain the result together with your other hormone tests
Contact a doctor straight away if
- The puncture site is very swollen, painful, and red
Common questions
If the antibodies are high, does that mean Graves disease?
It is an important sign, but the doctor decides based on all your tests and an exam.
Will I need to repeat this test?
Sometimes, yes. The doctor may repeat it during treatment to decide when to stop.