5-Flucytosine, Antimicrobial Drug Level
Label Mnemonic: 5FLUC
Epic Lab Code: LAB2512
Downtime Form: A-1a Miscellaneous Request
Commercial Mail-out Laboratory
5231 RCP
Collection Medium:
Red top tube 5 mL (Clot Activator)
Serum - Draw blood in a plain, red-top tube(s). Send 1 mL Serum for a peak (1-2 hr after oral dose, 30 min after intravenous infusion). (Absolute Serum Minimum: 0.3 mL) Trough samples should be drawn immediately prior to next scheduled dose.
Rejection Criteria:
Gel separator tubes.
Turn Around Time:
2 days upon receipt at reference laboratory
Reference Range:
Therapeutic concentration: Peak >25.0 mcg/mL (difficult infections may require higher concentrations)

Toxic concentration: Peak >100.0 mcg/mL
Interpretive Data:
Most individuals display optimal response to flucytosine when peak serum levels (1-2 hours after oral dosing) are >25.0 mcg/mL. Some infections may require higher concentrations for efficacy. Toxicity is more likely when peak serum concentrations are >100.0 mcg/mL.
Serum is the only acceptable sample.
Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
CPT Code: