Glossary of terms

Thyroglobulin (Tg)   

 A protein made by the thyroid gland. It is normally used to make thyroid hormones. 


Surgery to remove all (total thyroidectomy) or part (lobectomy/partial thyroidectomy) of the thyroid gland.

Thyroid hormone replacement therapy (THRT)    

The process of taking thyroid hormones in pill form, in order to keep the body’s metabolism going when natural thyroid hormones are low. These hormones can include thyroxine (T4), taken once daily by most people, and liothyronine (T3), usually taken two or three times a day. 

Thyroid stimulating hormone (TSH) 

A hormone made by the pituitary gland (just under the brain). It regulates the thyroid, encouraging it to absorb iodine and make thyroglobulin (Tg). 

Recombinant human thyroid stimulating hormone (rhTSH)    

Recombinant human TSH (rhTSH) is a highly purified, recombinant form of the naturally occurring human protein TSH. It is used as an alternative to thyroid hormone withdrawal for ablation and during the post-surgical follow-up of papillary and follicular thyroid cancer in order to avoid hypothyroidism.

Radioactive Iodine (RAI)    

Radioactive iodine, given in a capsule or liquid form, is absorbed and concentrated by the thyroid cells. Treatment with RAI destroys thyroid tissue but does not harm other tissue in the body.

RAI Ablation  

Radioiodine ablation is radiation therapy in which radioactive iodine is administered to destroy or ablate residual healthy thyroid tissue remaining after thyroidectomy.

Tri-iodothyronine (T3)    

A hormone that plays vital roles in the body’s metabolic rate, heart and digestive functions, muscle control, brain development and the maintenance of bones.

Thyroxine or tetraiodothyronine (T4)  

A hormone made by the thyroid gland. It controls metabolism and a range of other essential body functions. 

Ultrasound (US) 

A type of scan of the inside of the body using high frequency sound waves, in order to help detect any abnormal structures. 

Computerised tomography (CT Scan)  

A CT scan, makes use of computer-processed combinations of many X-ray images taken from different angles to produce cross-sectional (tomographic) images (virtual 'slices') of specific areas of a scanned body, allowing the user to see inside the body without cutting.

Well-differentiated thyroid cancer    A collective name for the two most common forms of thyroid cancer – papillary thyroid cancer and follicular thyroid cancer.