Draw tube or plastic pour off tube
- 2-8 C for 24 hours
- -20C up to 12 months
CLIA (chemiluminescent immunoassay)
- Normal range: 2.2-4.2 pg/mL
To identify patients with thyrotoxicosis whose T4 and FT4 concentrations are normal, while T3 is elevated. FT3 is useful to identify subclinical hyperthyroidism with suppressed TSH, and nnormal Ft4 and FT3 levels.