Tests
Main Content
T4, Free (Thyroxine)
| 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. | ||