Phenobarbital Level
| Abbrev Code: | PHENO | ||
| Order Code: | LAB30 | Order Name: | Phenobarbital Level |
| Synonyms: | Also see Free Phenobarbital (FPHENO, LAB3482) | ||
| Methodology: | Kinetic interaction of microparticles in a solution (KIMS) | ||
| CPT Codes: | 80184 x1, 80184 x1 | ||
| Turnaround Time: | Performed and reported 24 h/day. | ||
Collection Instructions
| Specimen: | Blood |
| Optimal Volume: | 2.5 mL |
| Minimum\Peds Volume: | 0.8 mL |
| Container: | Red (no gel) Alternate Containers: Purple (EDTA) |
| Collection Instructions: | Trough level is preferred; collect immediately before dose. It is advisable to monitor at the same time in the dosing schedule. |
| Causes for Rejection: | Collection in a gel tube. |
Processing and Shipping
| Specimen Processing: | Centrifuge and aliquot 1.25 mL, 0.3 mL minimum. Store in room temperature up to 48 hours. Alternatively, refrigerate. |
| Shipping Instructions: | Ship at room temperature to arrive within 48 hours. Alternatively, ship at refrigerated temperature. |
| Stability: | 7 days at room temperature; 7 days refrigerated; 1 year frozen. |
| Test Performed at or Referral Lab | Chemistry (Roche-Grand Itasca, Roche-Range, Roche-UMMC East) |
Interpretive
| Critical Range: | Greater than 50 ug/mL |
| Therapeutic Range: | 10-30 ug/mL
The therapeutic range of phenobarbital is correlated with seizure control as well as the absence of toxic effects, and is generally accepted to be between 10 and 30 ug/mL. Variation in metabolism and absorption of the drug may cause levels to rise above 40 ug/mL or fall below 15 ug/mL. The most frequent dose related side effect is sedation, to which a tolerance usually develops. Phenobarbital serum levels above 40 ug/mL are often associated with nystagmus, ataxia and dysarthria. At high doses, phenobarbital can cause an increase in seizure frequency. |
| Use: | Monitor therapeutic drug level of phenobarbital; use with primidone levels to monitor therapeutic drug level of primidone; evaluate phenobarbital toxicity. Half-life is 50-120 h (adult); and 40-70 h (child). |
Click HERE to Report test errors or omissions.
*If no email program is associated with this computer, please contact:
[email protected] for TestID: 1428"