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Test Code 5FLUOROCYT 5-Flucytosine, Serum

Reporting Name

5-Flucytosine, S

Useful For

Monitoring serum concentration during therapy

Evaluating potential toxicity

May aid in evaluating patient compliance


Specimen Required


Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

Collection Container/Tube:

Preferred: Red top

Acceptable: Serum gel

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL

Collection Instructions:

1. Serum for a peak level should be collected 1 to 2 hours after oral dose or 30 minutes after intravenous infusion. Trough specimens should be collected immediately prior to next scheduled dose.

2. Within 2 hours of collection, centrifuge, and aliquot serum to plastic vial.


Seattle Children's Hospital Note:

Collect 2 mL whole blood in Red Top.

Specimen Type

Serum

Specimen Minimum Volume

0.3 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 28 days
  Ambient  28 days
  Frozen  28 days

Day(s) Performed

Tuesday, Thursday

Seattle Children's Hospital Note:

TAT: 4 - 10 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Method Name

Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)

Method Description

5-Flucytosine is extracted by mixing serum samples with an acetonitrile and methanol mixture to precipitate proteins. The supernatant is removed and analyzed by an in-house developed liquid chromatography-tandem mass spectrometry method.(Unpublished Mayo method)

Reference Values

Therapeutic concentration:

Peak >25.0 mcg/mL (difficult infections may require higher concentrations)

Toxic concentration:

Peak >100.0 mcg/mL

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

80299

LOINC Code Information

Test ID Test Order Name Order LOINC Value
FLUC 5-Flucytosine, S 3639-2

 

Result ID Test Result Name Result LOINC Value
82741 5-Flucytosine, S 3639-2

Report Available

3 to 8 days

Reject Due To

Gross hemolysis OK
Gross lipemia OK
Gross icterus OK

Forms

If not ordering electronically, complete, print, and send a Therapeutics Test Request (T831) with the specimen.