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Test Compendium

1902: Free T4 by Dialysis/Mass Spec

Test Code

  • 1902

Test Synonym

  • Thyroxine (T4), Free by Dialysis/Mass Spectrometry


  • 1 mL

Minimum Volume

  • 0.5 mL

Specimen Requirements

  • Serum Or Plasma


  • Transfer Tube Serum from Red Top, Transfer Tube EDTA Plasma or Gel-barrier Tube


  • See Stability

CPT Codes

  • 84439
    *The CPT codes provided are based on AMA guidelines and are provided for informational purposes only. CPT coding is the responsibility of the billing entity. Please direct any questions regarding the CPT coding to the payer being billed.

Special Instructions

  • Draw Red-top tube, Gel-barrier tube OR lavender-top (EDTA) tube. Serum or plasma must be separated from cells within 45 minutes of venipuncture. Send serum or plasma in plastic transport tube. Please indicate on the transfer tube if serum from a Red-top or EDTA plasma.

Additional Information

  • This test cannot be ordered with 6147 Thyroxine, Free (FT4)

Specimen Stability

  • Room Temp 2 days, Refrigerated 5 days, Frozen 453 days