Therapeutic drug management
Trough levels are most reproducible
Dk green heparin (Li or Na), no gel
Immediately following collection, mix sample thoroughly by gently inverting 8 - 10 times to prevent clotting
Refrigerated (preferred)
Ambient - 3 days
Frozen (OK)
Gel-barrier tubes are not recommended
Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS)
Total: 0.4 - 4.0 µg/mL
Free: 0.2 - 2.0 µg/mL
Total: >10.0 µg/mL
Free: >4.0 µg/mL