| Ordering Code | 441 | 
|---|---|
| Test Name | Phenobarbital | 
| Preferred Specimen | Plasma | 
| Preferred Container | Lithium Heparin PST (Green) | 
| Other Specimen/Container | Serum in Plain (Red), Serum in SST (Gold) | 
| Optimum Volume | 0.5 mL | 
| Handling Instructions | Send aliquot if transport time >24 hours. | 
| Transport Requirements | Oahu: Refrigerated Airline: Frozen | 
| Specimen Stability | Refrigerated: 24 Hours (Centrifuged, unaliquoted gel separator tubes) 4 Days (Aliquot) Frozen: 1 Month (Aliquot) Frozen samples should be thawed only once Test cannot be added to >24 hours unaliquoted specimens collected in a gel separator tube. | 
| Rejection Criteria | Grossly hemolyzed, Insufficient quantity, Specimen older than stability limits, Uncentrifuged gel separator tube specimens >2 hours old, Unaliquoted gel separator tube specimens >24 hours old | 
| Avail. Stat | YES | 
| Analytic Time | 1 Day | 
| Methodology | Kinetic Interaction of Microparticles in Solution (KIMS) | 
Reference range(s)
The reference ranges listed below are valid on this date of October 31, 2025.
      | Component | Age | Male Norm | Male Critical Low | Male Critical High | Female Norm | Female Critical High | Female Critical Low | Units | Add'l info | 
|---|---|---|---|---|---|---|---|---|---|
| Phenobarbital | ALL | 15.0-40.0 | >= 50.0 | 15.0-40.0 | >= 50.0 | ug/mL |