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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 be useful to evaluate patient compliance


Specimen Required


Container/Tube:

Preferred: Red top

Acceptable: Serum gel

Specimen Volume: 0.5 mL

Collection Instructions: 

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

2. Spin down within 2 hours of draw.


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
Serum Frozen (preferred) 28 days
  Ambient  28 days
  Refrigerated  28 days

Day(s) and Time(s) Performed

Tuesday, Thursday, 9 a.m.

Performing Laboratory

Mayo Medical Laboratories in Rochester

Method Name

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

Method Description

5-Flucytosine is extracted by mixing serum samples with acetonitrile and methanol mixture to precipitate proteins. The supernatant is removed and analyzed by an in-house developed liquid chromatography-tandem mass spectrometry (LC-MS/MS) method.(Unpublished Mayo method)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. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

80299

LOINC Code Information

Test ID Test Order Name Order LOINC Value
FLUC 5-Flucytosine, S In Process

 

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

Reject Due To

Hemolysis

Mild OK; Gross OK

Lipemia

Mild OK; Gross OK

Icterus

Mild OK; Gross OK

Other

Whole blood