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Test Compendium


Test Code

  • 2222

Test Synonym

  • Tryptophan, Plasma

Minimum Volume

  • 0.25 mL

Specimen Requirements

  • Plasma


  • Transfer Tube- Frozen- Plasma


  • Frozen

Turn Around Time

  • 8 days

CPT Codes

  • 82131
    *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

  • 0.5 mL Heparinized Plasma, FROZEN

Additional Information

  • 0.5 mL Frozen Heparinized Plasma from a Green Top Tube. Separate plasma from cells. Transfer specimen to plastic transport tube before freezing. To avoid delays in turnaround time when requesting multiple tests on frozen samples, PLEASE SUBMIT SEPARATE FROZEN SPECIMENS FOR EACH TEST REQUESTED. Blood spots on filter paper are not an acceptable specimen type. This test is NOT to be used for newborn screening.

Specimen Stability

  • AMBIENT: Unstable REFRIGERATED: Unstable FROZEN: 14 days