| A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # |
T3, Free
MessageTest performed at York Hospital Laboratory.
Test Code
FT3
Alias/See Also
Free T3
CPT Codes
84481
Preferred Specimen
0.2 mL serum collected in a serum separator tube (SST)
Other Acceptable Specimens
0.2 mL serum collected in a no additive (red-top) tube, transferred to a plastic screw-cap vial 0.2 mL plasma collected in a lithium heparin (green-top) gel separator tube
Transport Temperature
Refrigerated
Specimen Stability
Room temperature: 4 hours
Refrigerated: 7 days
Frozen: 4 weeks
Refrigerated: 7 days
Frozen: 4 weeks
Methodology
Chemiluminescence
Setup Schedule
Daily
Report Available
Next Day
Reference Range
2.77-5.27 pg/mL
Clinical Significance
- In hyperthyroidism, FT3 concentrations are generally elevated and give efficient discrimination at the euthyroid/toxic borderline, providing an effective method for confirming hyperthyroidism and monitoring of its treatment. In hypothyroidism, FT3 concentrations tend to be lower, but the decrease is insufficient to give clear diagnostic information. FT3 concentrations are independent of the concentration of thyroid hormone binding proteins, and may be measured in patients with elevated or reduced binding protein concentrations without the need for additional tests of binding capacity.
