Thyroxine (T4), Free, Dialysis/Mass Spectrometry (Endocrine Sciences)
Synonyms
- Free Thyroxine (T4) by Dialysis/Mass Spectrometry
Expected Turnaround Time
6 - 11 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Documents
For more information, please view the literature below.
Specimen Requirements
Specimen
Serum or plasma
Volume
1 mL
Minimum Volume
0.5 mL; pediatric volume: 0.4 mL (Note: This volume does not allow for repeat testing.)
Container
Red-top tube, gel-barrier tube, or lavender-top (EDTA) tube
Collection
Serum or plasma must be separated from cells within 45 minutes of venipuncture. Send serum or plasma in plastic transport tube. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.
Storage Instructions
Freeze
Stability Requirements
Temperature | Period |
|---|---|
Room temperature | 2 days |
Refrigerated | 5 days |
Frozen | 453 days |
Freeze/thaw cycles | Stable x3 |
Test Details
Methodology
Direct dialysis mass spectrometry; high-pressure liquid chromatography/mass spectrometry (HPLC/MS)
Reference Interval
See table.
Age | Range (ng/dL) |
|---|---|
Premature (0 to 4 wk) | 0.86−4.46 |
Newborn | |
0 to 2 wk | 0.84−4.97 |
2 wk to 12 m | 0.81−2.12 |
Children 1 to 11 y | 0.65−1.9 |
Pubertal children and adults | 0.8−1.7 |
Pregnant female | |
first trimester (0 to 13.3 wk) | 0.65−1.4 |
second trimester (13.4 to 26.6 wk) | 0.5−1.3 |
third trimester (>26.6 wk) | 0.5−1.1 |
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 501902 | Free T4 by Dialysis/Mass Spec | 6892-4 | 501903 | Free T4 by Dialysis/Mass Spec | ng/dL | 6892-4 |
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