Thyroxine, Free T4F
| Method(s) | LOCI | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Specimen Required | |||||||||
| Collect | One 5 mL gold (SST) top tube. Also acceptable: heparinized plasma. |
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| Transport | 1 mL serum at 2-8ºC (Min: 0.5 mL) |
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| Stability | Ambient: 24 hours; Refrigerated: 14 days; Frozen: 3 months |
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| Schedule | Daily, except Sundays | ||||||||
| Billing Code | 1010074 | ||||||||
| CPTCode | 84439 | ||||||||
| Notes | Results of this test may be falsely elevated in patients taking over-the-counter biotin supplements. |
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| Preferred Specimen Collection Device(s) | |||||||||
| Reference Interval | |||||||||
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