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Test Name:
T4, Total
- SBMF No:
30213 - Performance Lab Name:
Automated Lab - Test Mnemonic:
T4- - ABN:
May be required – Medical Necessity - CPT Code:
84436 - LOINC Code:
3026-2 - Also Known As:
T4
Thyroxine
Total T4
Total Thyroxine - Spec Type:
Serum - Spec Container:
Gold top (SST) or red top (serum) tube - Alt Spec Type:
Plasma - Alt Spec Container:
Lavender top (EDTA) tube, green top (heparin) tube, or light blue top (3.2% buffered sodium citrate) tube - Pref Vol:
1.0 mL - Min Vol:
0.3 mL - Fasting:
No - Spec Collect:
Routine venipuncture - Spec Process:
Serum sample tubes, clot 30 minutes
Promptly centrifuge 15 minutes
Immediately transfer serum or plasma to separate plastic tube
Properly centrifuged gel barrier tube sample does not require transfer of serum to separate tube - Spec Store Transport:
Refrigerated - Spec Stability:
1 week refrigerated (2-8°C)
6 months frozen (-20°C) – Do not use frost-free units that undergo repeated freeze/thaw cycles - Spec Reject:
Heat-inactivated sample - Methodology:
Enzyme Immunoassay (EIA) - Use:
Used in the diagnosis and treatment of thyroid disorders - Clinical Significance:
Thyroxine (T4) is the most abundant iodothyronine in thyroglobulin. The majority of circulating triiodothyronine (T3) is formed following mono-deiodination of T4 in the peripheral tissues. In serum, T4 is bound to thyroxine-binding globulin (TBG), thyroxine-binding prealbumin (TBPA), and albumin. The serum free T4 concentration is less than 0.1% of the total T4 concentration.
Also see:
- Reference Range:
T4 µg/dL Age Reference Range 0-1 month 10.1-20.0 µg/dL 1-4 months 7.5-16.5 µg/dL 4 months-1 year 5.5-14.5 µg/dL 1-6 Years 5.6-12.6 µg/dL 6-10 Years 4.9-12.0 µg/dL Greater than 10 years 4.6-12.0 µg/dL - Day Run:
Sun-Sat (daily) - Time Run:
As received - Time Reported:
4 hours - Test Type:
HORMONE
