T4, Free

Abbrev Code:FT4   
Order Code:LAB127Order Name:T4 Free
Synonyms:Free T4 (Thyroxine); FT4
Methodology:Roche: Electrochemiluminescence immunoassay (ECLIA)
Vista: Chemiluminescence
CPT Codes: 84439 x1, 84439 x1
Turnaround Time:Varies by site.
Associated Links:

Roche Go Live Schedule

Collection Instructions

Optimal Volume:2.5 mL
Minimum\Peds Volume:0.6 mL
Collection Instructions:Chemistry Tests Containers Chart
Causes for Rejection:Gross hemolysis
Contraindications:Large doses of biotin (10 mg or more per day) may cause clinically significant interference in free T4 levels. If interference is suspected, it is strongly recommended that biotin is discontinued for at least one week prior to retesting.

Processing and Shipping

Specimen Processing:Centrifuge and aliquot 1.25 mL, 0.2 mL minimum. Store in refrigerator.
Shipping Instructions:Ship at refrigerated temperature.
Stability:Roche: 5 days at room temperature; 7 days refrigerated; 30 days frozen. Freeze only once.
Vista: 24 hours at room temperature; 14 days refrigerated; 3 months frozen.
Test Performed at or Referral Lab Chemistry  (CSC Maple Grove, Roche-Grand Itasca, Roche-Lakes, Roche-Northland, Roche-Range, Roche-Ridges, Roche-Southdale, Roche-St. John's, Roche-UMMC East, Roche-UMMC West)


Reference Range:
Roche F/M ng/dL
0-5 d 0.9-2.5
6 d - 2 mo 0.9-2.2
3-12 mo 0.9-2.0
1-5 y 1.0-1.8
6-10 y 1.0-1.7
11-19 y 1.0-1.6
20 y & older 0.9-1.7
Vista Female
0-3 days 0.93-1.44 0.97-1.87
4-30 d 0.81-1.44 0.78-1.52
1 mo & older 0.76-1.46 0.76-1.46

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