Total T3
This lab test helps to evaluate thyroid function.
Total T3 Overview
Total T3 consists of both bound and free fractions. Not as useful as free T3, because only the free T3 fraction is metabolically active. However, may be useful in locating problems with Thyroxine-binding globulin (TBG), or if looking for problems with peripheral conversion of T4 to T3.
Total T3 is measured in nanograms per deciliter (ng/dL). The normal ranges for total T3 are the following:
- 1 -9 years: 94 -269 ng/dL
- 10-19 years: 102 -200 ng/dL
- > 20 years old: 80 -200 ng/dL
Technique
Blood draw
Preparation
Fasting is not required before the test.
Your doctor may withhold medications which that affect test results.
What the results mean
Values that are above normal could indicate hyperthyroidism or grave's disease.
A value that is lower than normal can be associated with hypothyroidism, anorexia nervosa, the elderly, a genetic deficiency of thyroxine-binding globulin, goiter (caused by iodine deficiency), hepatic cirrhosis, and iodine deficiency (severe).
