ARUP's Laboratory Test Directory

Thyroxine : 0070140

Mnemonic: T4

Ordering Recommendation: Not recommended for routine thyroid screening.
Methodology: Quantitative Electrochemiluminescent Immunoassay
Performed: Sun-Sat
Reported: Within 24 hours
Specimen Required: Collect: Serum separator tube or plasma separator tube. Also acceptable: Lavender (EDTA).

Specimen Preparation: Allow specimen to clot completely at room temperature. Separate serum or plasma from cells ASAP or within 2 hours of collection. Transfer 1 mL serum or plasma to an ARUP Standard Transport Tube. (Min: 0.5 mL)

Storage/Transport Temperature: Refrigerated.

Unacceptable Conditions: Grossly hemolyzed specimens.

Stability (collection to initiation of testing): After separation from cells: Ambient: 24 hours; Refrigerated: 1 week; Frozen: 1 month
Reference Interval:
 
Cord blood 6.60-17.50 µg/dL
0-3 days 5.37-22.40 µg/dL
4-30 days 5.24-23.20 µg/dL
1-23 months 5.37-16.00 µg/dL
2-6 years 5.26-14.80 µg/dL
7.11 years 5.70-14.10 µg/dL
12-19 years 4.74-14.60 µg/dL
20 years and older 5.10-14.10 µg/dL

CPT Code(s): 84436
Cross References: T4 (Thyroxine), Total T4 (Thyroxine)