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Test Code FT4 T4 (Thyroxine), Free, Plasma or Serum

Additional Codes

Ordering Mnemonic




Performing Laboratory

Holland Hospital Laboratory Services

Specimen Requirements

Specimen must arrive within 48 hours of draw.


Submit only 1 of the following specimens:



Container/Tube: Mint-top (lithium heparin) tube

Specimen Volume: 1 mL of plasma

Collection Instructions:

Note: 1. Indicate plasma.
2. Label specimen appropriately (plasma).



Container/Tube: Serum gel tube

Specimen Volume: 1 mL of serum

Collection Instructions: If there is a delay in transport of ≥48 hours, send specimen frozen in plastic vial.

Note: 1. Indicate serum.

2. Label specimen appropriately (serum).

Specimen Transport Temperature

Refrigerate; Freeze if >48 hours

Day(s) Test Set Up

Monday through Sunday

Reference Values

0.61-1.24 ng/dL