Thyroxine and triiodothyronine can be measured as free thyroxine and free triiodothyronine , which are indicators of thyroxine and triiodothyronine activities in the body. They can also be measured as total thyroxine and total triiodothyronine , which also depend on the thyroxine and triiodothyronine that is bound to thyroxine-binding globulin . A related parameter is the free thyroxine index , which is total thyroxine multiplied by thyroid hormone uptake , which, in turn, is a measure of the unbound thyroxine-binding globulins.  Additionally, thyroid disorders can be detected prenatally using advanced imaging techniques and testing fetal hormone levels. 
The majority of patients appeared to be eumetabolic and maintained a near normal serum TSH concentration. They were classified as having generalized resistance to TH (GRTH). In such individuals, the defect seemed to be compensated by the high levels of TH. In contrast, patients with equally high levels of TH and nonsuppressed TSH that appeared to be hypermetabolic, because they were restless or had sinus tachycardia, were classified as having selective pituitary resistance to TH (PRTH). Finally, the occurrence of isolated peripheral tissue resistance to TH (PTRTH) was reported in a single patient (42). No mutation in the THRB gene of this patient was found (43) and no similar cases have been reported. More common in clinical practice is the apparent tolerance of some individuals to the ingestion of supraphysiological doses of TH.
If thyroid cancer is suspected and surgery may be required, your physician may ask for a blood test known as thyroglobulin. Thyroglobulin is a protein made only by thyroid cells. If the thyroglobulin level at baseline is detectable or elevated (this means the gland does in fact make the protein) it can be used as a tumor marker. After a total thyroidectomy for cancer (removal of the entire thyroid gland) the level should fall to an undetectable range since the cells that make thyroglobulin have been removed. If the level remains detectable after surgery, there is a possibility of thyroid tissue elsewhere in the body, and metastatic disease should be considered. If the level is undetectable for a period of time after surgery and then starts to climb, a recurrence of the cancer - either at the primary site or elsewhere in the body should be considered.