Thyroid function test
A thyroid function test is a type of blood test.
A sample of your blood is taken and measured for levels of:
- thyroid-stimulating hormone (TSH)
- thyroxine and triiodothyronine (the thyroid hormones)
If you have lower- or higher-than-average levels of these hormones, it could mean you have a thyroid disorder or you're at risk of developing one in the future.
Referral to a hospital specialist
Your GP may refer you to a specialist thyroid clinic or a specialist in hormone-related illnesses (an endocrinologist) if you have a thyroid swelling and:
- it's getting bigger
- you have a family history of thyroid cancer
- you have had radiation treatment to your neck
- you have swollen lymph nodes in your neck
- you're a child or teenager
- you're 65 or over
- your voice has changed
- you're making a high-pitched noise as you breathe
- you're having difficulty breathing or swallowing
If you're referred to a specialist, you may have further tests on the goitre in hospital.
- a radioactive iodine scan
- an ultrasound scan
- fine needle aspiration (biopsy)
Radioactive iodine scan
With this scan, a small amount of radioactive iodine is injected into a vein in your arm.
The iodine builds up in your thyroid gland, which can then be studied using a special camera.
The scan can provide useful information about the structure and function of your thyroid gland.
As the amount of radiation used is very small, it's perfectly safe for most people. But it may not be suitable if you're pregnant.
An ultrasound scan uses high-frequency sound waves to create an image of part of the inside of your body.
It can be used to:
- build up a picture of the inside of your thyroid gland
- assess the size of your thyroid gland
- check whether there are any enlarged nodules in your thyroid gland not found during the physical examination
Fine-needle aspiration is a procedure where a sample of the goitre is extracted so the cells inside it can be tested.
This procedure is often known as a biopsy.
During the procedure, a fine needle on the end of a syringe is inserted into the goitre in your throat.
A sample of the fluid or tissue inside the goitre is sucked through the needle into the syringe.
The sample can be examined under a microscope to determine what kind of cells are inside the goitre.