Thyroxine (Free)

General Information

Method

Chemiluminescence

Reference Range

Units: ng/dL

Female		Male
Age	Range	Age	Range
0-	0.6-1.2	0-	0.6-1.2

Effective date: 09/19/2006

Interferences and Limitations

Biotin supplements can cause falsely elevated values. See Limitations of Laboratory Testing for details.

Specimen Type: Blood
Collection: HMC and UW-MT Onsite Locations:
Preferred: 4 mL blood in LIME GREEN PST tube
Also Acceptable: 4 mL blood in ORANGE RST, GOLD SST, RED TOP or GREEN TOP tube
Pediatric, Preferred: 1 Full LIME GREEN MICROTAINER
Pediatric, Also Acceptable:1 Full GOLD MICROTAINER
Unacceptable: LAVENDER TOP

Offsite Clinic or Other Locations:
Preferred: 4 mL blood in GOLD SST tube
Also Acceptable: 4 mL blood in ORANGE RST or LIME GREEN PST, RED TOP or GREEN TOP tube
Pediatric, Preferred: 1 Full LIME GREEN MICROTAINER
Pediatric, Also Acceptable:1 Full GOLD MICROTAINER
Unacceptable: LAVENDER TOP
Quantity: Requested: 1 mL serum/plasma
Minimum: 0.5 mL serum/plasma

Receiving Instructions: Refrigerate serum/plasma.
Stability: Room Temperature: 8 hours; Refrigerator: 48 hours; Freeze at -20°C: >48 hours. Thaw sample only once

Lab Department

Chemistry, Automated Panels(CHA)

Frequency

Daily

Available STAT?

Performing Location(s)

HMC	Chemistry, Automated 206-520-4600 325 9th Ave, Rm # GWH-47, Seattle, WA 98104-2420
UW-NW	Main Lab 206-668-1344 UW Medical Center – Northwest 1550 N 115th Street, A200 Seattle, WA 98133
FHCC	Fred Hutch Alliance Lab 206-606-1088 825 Eastlake Ave, Seattle, WA 98109
UW-MT	Chemistry, Automated 206-520-4600 Clinical Lab, Room NW220, University of Washington Medical Center, 1959 NE Pacific street, Seattle, WA 98195