TOTAL THYROXINE (TT4)

Total circulating T4, used in thyroid function assessment.

LIS TEST CODE: TT4

CPT CODE: 84436

ALIASES: TT4, Total T4, Syn-Thyroid, T4, Serum, Tetraiodothyronine, Thyroid Hormone

METHODOLOGY: Chemiluminescent Microparticle Immunoassay (CMIA)

SPECIMEN:

- Type: Serum

- Container: Gold Top (SST) Vacutainer

- Minimum Volume Required: 1 mL

- Storage/Handling: Allow 30 minutes for blood to clot, then centrifuge specimen at 3500 RPM for 10 minutes. Maintain specimen in the refrigerator until testing can be performed.

- Stability:

Room Temperature (20-25 °C): Not Accepted

Refrigerated (2-8 °C): 6 days

Frozen (-20 °C or colder): Not Accepted

- Turnaround Time: 24 hours from receipt.

Special Instructions: N/A

REJECTION REASONS: QNS, Gross Hemolysis, Gross Lipemia, Contamination, Stability Violation, Expired Container, Incorrect Container

REFERENCE RANGES:

Males & Females (ug/dL)

1 - 5 years of age: 6.0 - 14.7

6 - 10 years of age: 6.0 - 13.8

11 - 19 years of age: 5.9 - 13.2

>= 20 years of age: 4.5 - 11.7