MICHIGAN INNOVATIVE DIAGNOSTICS

Unbound thyroid hormone level used to evaluate thyroid function.

​

LIS TEST CODE: FT4

​

CPT CODE: 84439

​

ALIASES: FT4, Free T4

​

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: If testing will be delayed for more than 24 hours, remove serum from the separator gel and transfer into a separate plastic screw-cap transport container.

​

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

​

REFERENCE RANGES:

​

Males & Females (ng/dL)

​

1 - 5 years of age: 1.00 - 1.80

6 - 10 years of age: 1.00 - 1.70

11 - 19 years of age: 1.00 - 1.60

>= 20 years of age: 0.90 - 1.70

​​​​​​​​​

​