| Test Name: | T4, Free (Thyroxine) |
| Epic Order Code: | LAB127 |
| CPT Code: | 84439 | | |
| Specimen(s) Type: | Plasma or Serum, 0.5 mL |
| Acceptable Container(s): |   Tube tops are light green and gold. |
| Testing Schedule: | 24 hrs/day, 7 days/week |
| Turn Around Time: | STAT: 1 hour |
| | Routine: 2 hours |
| Collection Information: | No special patient preparation is required. Obtain specimen by standard collection procedures. |
| Transport Information: | Deliver to lab immediately. All specimens must be signed into the laboratory. |
| Reference Clients: | If unable to deliver to the lab within 1 hour, centrifuge the specimen and remove plasma/serum from the red cells. Store and transport at 2-8° C. Specimen must be received in the lab within 24 hours. |
| Causes for Rejection: | Improperly labeled, incorrect container, contaminated, insufficient quantity, incorrect/delay in transport. |
| Reference Range: | 0 - 4 days: | 0.66 - 2.71 ng/dL |
| | 4 - 60 days: | 0.83 - 3.09 ng/dL |
| | 2 mos - 2 yrs: | 0.48 - 2.34 ng/dL |
| | 2 - 7 yrs: | 0.85 - 1.75 ng/dL |
| | 7 - 12 yrs: | 0.90 - 1.67 ng/dL |
| | 12 - 19 yrs: | 0.93 - 1.60 ng/dL |
| | > 19 yrs: | 0.93 - 1.70 ng/dL |
| Additional Information: | Furosemide causes elevated free T4 results at the daily therapeutic dosage level. |