Sign in →

Test Code T4 Thyroxine Level

Clinical System Name

T4

Synonyms

Total T4

TT4

Sample Requirements

Specimen: Whole blood

Container(s): Gold SST, Red, Gold Microtainer, Lavender/EDTA, Lt. Green/Lithium Heparin, Dark Green/Sodium Heparin

Preferred Vol: 1.0 mL

Minimum Vol: 0.5 mL

 

 

Processing Instructions

Reject due to: gross lipemia

Spin: Y

Aliquot: Y

Temp: 2-8 C

Storage location: CPA refrigerator,  FrigD rack. Serum/plasma should be removed from separator for storage.

 

Note: Minimum volume of 1.0 mL serum may be shared with TSH, T3, T4, free T3, and free T4

 

Off-site collection: Spin blood. Transfer serum/plasma to plastic aliquot container. Note whether patient is on endocrine therapy. Refrigerate.

Stability

Specimen Type Temperature Time
gel separator with serum/plasma Refrigerated 48 h
separated serum/plasma Room temp 2 h
  Refrigerated 5 d
  Frozen -20 C 4 w

 

Availability

STAT Performed TAT
N M-Sa, day shift 1-3 d

 

Performing Laboratory

Seattle Children's Laboratory    

Department

Department:  Chemistry

Location: Chem West

Phone Number:  (206) 987-2617

 

 

 

Reference Range

  Age 

(mcg/dL)

Birth - 3 days  8.0 - 20.0 
3 days - 1 month 5.0 - 15.0
 1 - 12 months 6.0 - 14.0
1 - 5 years  4.5 - 11.0
5 - 18 years 4.5 - 10.0
18 years - adult 5.5 - 10.9

 

Methodology

Method: Chemiluminescence by Vitros 3600, third generation assay

Analytical Volume: 0.200 mL serum/plasma

Limitations: Turbidity may affect results.

CPT Codes

84436