T4 : (tetra-iodothyronine)

 

[normal range is 7.0 - 9.0]

T4 is the major hormone secreted by the thyroid making up 85 - 90% of the hormone. T4 exists as both a bound and non-bound form. T4 is predominately bound to thyroid binding globulin (TBG), pre-albumin, and albumin.

 

If the patient exhibits an increased T value, consider the following:

  • Hyperthyroidism
  • Thyrotoxicosis
  • Birth control pills
  • Pregnancy
  • Neoplasm

 

If the patient exhibits a decreased T value, consider the following:

  • Hypothyroidism
  • Myxedema
  • Hypoproteinemia
  • Nephrosis
  • Simmonds disease