Test Name: Phenobarbital
Health Link Test Code: PHEN
LIS Test Code: PENO
CPT Code(s): 80184
Methodology: Particle Enhanced Turbidometric Inhibition Immunoassay (PETINIA)
Days Performed: Daily, 24 hours.
In-Lab Turnaround Time: 4 hours.
Stat In-Lab Turnaround Time: 1 hour.
Collection Container: Red top
Also Acceptable: Green top (with lithium heparin anticoagulant)
Collect specimen within 30 minutes prior to the morning dose.
Collection Volume: 2 mL
Pediatric Collection Volume: 0.4 mL
Sample Analyzed: Serum or plasma
Testing Volume: 1 mL
Pediatric Testing Volume: 0.2 mL
Centrifuge. Transfer cell-free serum or plasma to plastic vial. Refrigerate.
Transport specimen to the laboratory. Transport with coolant pack if coming from clinic location.
Specimens collected in red cap with yellow ring (SST) or green cap with yellow ring (PST)tubes are not acceptable.
Generally effective therapeutic concentration: 15.0-40.0 ug/mL
Critical Calls: yes
Result of "BELOW" indicates that the level is below the instrument detection limit of 2.0 ug/mL. The half-life is approximately 4 days. The average peak blood concentration following oral administration is approximately 4.5 hours. Concurrent administration with valproic acid may cause a marked increase in the phenobarbital concentration. It may require 14-21 days to achieve steady state. Phenobarbital is considered an hepatic enzyme inducer. It is not extensively protein bound and is both hepatically and renally eliminated.