T4 (THYROXINE), TOTAL (REFL)

Clinical Significance
T4 (Thyroxine), Total (REFL) - For diagnosis of hypothyroidism and hyperthyroidism

Preferred Specimen(s)
1 mL serum

Alternative Specimen(s)
Plasma collected in: Sodium heparin (green-top) or lithium heparin (green-top) tube

Minimum Volume
0.5 mL

Collection Instructions
Note: Free T4 Index (T7) will only be calculated and reported if order code 861 (T3 Uptake) is ordered as well.

Transport Container
Serum Separator Tube (SST®)

Transport Temperature
Room temperature

Specimen Stability
Room temperature: 7 days
Refrigerated: 7 days
Frozen: 28 days
Setup Schedule

Includes
This is a client specific reflex test. Reflex criteria has been pre-defined by the ordering physician. Additional testing will be performed at an additional charge.

Methodology
Immunoassay (IA)

Reference Range(s)
T4 (Thyroxine), Total
     Male (mcg/dL)    Female (mcg/dL)
<1 Month    4.5-17.2    4.5-17.2
1-23 Months    5.9-13.9    5.9-13.9
2-12 Years    5.7-11.6    5.7-11.6
13-20 Years    5.1-10.3    5.3-11.7
>20 Years    4.9-10.5    5.1-11.9
Free T4 Index (T7)    1.4-3.8