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HelpTest Code FT3CC T3, Free
Useful For
Free triiothyronine (T3) is a second- or third-level test of thyroid function; it provides further confirmation of hyperthyroidism, supplementing the tetraiodothyroxine (T4), sensitive tyrotropin (sTSH) and total T3 assays
Evaluating clinically euthyroid patients who have an altered distribution of binding proteins
Monitoring thyroid hormone replacement therapy
Reference Values
2.0-4.4 pg/ml
Day(s) Test Performed
Tuesday and Friday
Specimen Requirement
High doses of biotin will affect this assay
Serum
Draw blood in a gold-top (serum separator) gel tube. Label the specimen with the patient’s name (first and last), date of birth, date and time of draw, phlebotomist’s initials, and as serum. Spin down and send 1 mL of serum refrigerated.
Specimen stability:
8 hours at room temperature
2 days refrigerated at 2-8°C
Freeze at ≤ -20°C for longer storage
Minimum volume:
0.5 mL
CPT Codes
84481
Method
Electrochemiluminesence Immunoassay