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Test Code FLUC 5-Flucytosine, Serum

Important Note

Serum for a peak level should be collected 1 to 2 hours after oral dose, 1 hour after intramuscular dose, or 30 minutes after intravenous infusion.

Trough specimens should be collected immediately prior to next scheduled dose.

Additional Codes

Epic Ordering Code LAB3041102
NBS code LBC01092
Service code 36885

Reporting Name

5-Flucytosine, S

Specimen Type

Serum


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, 1 hour after intramuscular 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 into a plastic vial.


National University Hospital-Singapore Note:

NUH Outreach Laboratories:
Specimen Requirements
Submit only one of the following:
Preferred: Red Top
Acceptable: Yellow Top
Processing Requirements
Centrifuge and aliquot serum into a plastic vial wtihin 2 hours.
Specimen type: Serum
Volume: 0.5 mL
Storage/transport requirements: Refrigerated

Forms

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

Specimen Minimum Volume

0.3 mL

Specimen Stability Information

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

Reject Due To

Gross hemolysis OK
Gross lipemia OK
Gross icterus OK

Method Name

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

Day(s) Performed

Tuesday, Thursday

Report Available

3 to 8 days

Reference Values

Therapeutic concentration:

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

Toxic concentration:

Peak >100.0 mcg/mL

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful For

Monitoring serum concentration during therapy

 

Evaluating potential toxicity

 

May aid in evaluating patient compliance

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

Secondary ID

82741

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.
National University Hospital-Singapore Additional Information:

Last updated 29/06/2026