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HelpTest Code LAB3061 Free Triiodothyronine (T3)
Clinical System Name
Free Triiodothyronine (T3)
Synonyms
Free T3; FT3
Sample Requirements
Specimen:Whole blood
Container(s): Gold SST Microtainer, Gold SST, Lt green/ Li heparin microtainer, Dark Green/ Na heparin, Lavender/EDTA, Red
Preferred Vol: 1 mL
Minimum Vol: 0.5 mL
Note:
Processing Instructions
Reject due to:
Spin: Y
Aliquot: Y
Temp: 2 - 8 C
Storage location: CPA Refrigerator, FrigD rack. Serum/plasma should be removed from separator for storage.
Off-site collection: Spin blood and aliquot in plastic aliquot tube. Send refrigerated.
Note: Minimum volume of 0.5 mL SERUM (FT4 requires serum) may be shared with TSH, T4, free T3, and free T4.
Stability
| Specimen Type | Temperature | Time |
|---|---|---|
| gel separator with serum/plasma | Refrigerated | 24 h |
| serum/plasma | Room temp | 2 h |
| Refrigerated | 6 d | |
| Frozen | 4 w |
Availability
| STAT | Performed | TAT |
|---|---|---|
| N | M - Sa | 1 - 3 d |
Performing Laboratory
Seattle Children's Laboratory
Department
Department: Chemistry
Location: Chem West
Phone Number: (206) 987-2617
CPT Codes
84481
Methodology
Method:Chemiluminescent microparticle immunoassay (CMIA) by Abbott Alinity i
Analytical Volume: 0.15 mL
Limitations:
Reference Range
FT3 transitioned platforms from Ortho Vitros 3600 to Abbott Alinity i on August 8, 2022.
There is a 40% negative bias with the new method.
| Age | pg/mL |
|---|---|
| 0-3 d | 3.51 - 6.49 |
| 4d - <1 yr | 2.32 - 4.87 |
| 1 - <12 yr | 2.79 - 4.42 |
| 12 - <15 yr | 2.50 - 3.95 |
| 15 - <19 yr | 2.31 - 3.71 |
| >19 yr | 1.58 - 3.91 |