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PHENOBARBITAL, SERUM
Test Code7823
Alias/See Also
Luminal®
CPT Codes
80184
Preferred Specimen
"Serum or plasma
1 mL
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1 mL
"
Minimum Volume
"0.3 mL
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"
Instructions
"Transfer separated serum or plasma to a plastic transport tube. Peak: 4 to 12 hours after dose; trough: immediately prior to next dose.
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Transport Container
"Red-top tube or green-top (heparin) tube. Do not use a gel-barrier tube. The use of gel-barrier tubes is not recommended due to slow absorption of the drug by the gel. Depending on the specimen volume and storage time, the decrease in drug level due to a
Transport Temperature
refrigerated
Specimen Stability
"
Room temperature---14 days
Refrigerated---14 days
Frozen---14 days
Freeze/thaw cycles---Stable x3
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Room temperature---14 days
Refrigerated---14 days
Frozen---14 days
Freeze/thaw cycles---Stable x3
"
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
"Gel-barrier tube; hemolysis; severe lipemia; icteric specimen
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Methodology
"Immunoassay "
Reference Range
"Reference Interval:
Therapeutic: 15-40 µg/mL
Critical Values:
Potentially toxic: >40 µg/mL
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Therapeutic: 15-40 µg/mL
Critical Values:
Potentially toxic: >40 µg/mL
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Clinical Significance
"Phenobarbital, a long-acting barbiturate, is effective in generalized tonic-clonic and simple partial seizures. Higher plasma concentrations may be required to control the latter. Complex partial seizures do not respond as well, and absence seizures are not relieved and may be exacerbated. Phenobarbital frequently is used in the treatment of neonatal seizures and may be the initial drug employed in young children; however, because of increasing concern about adverse neuropsychological reactions to sedative/hypnotic antiepileptic drugs, many neurologists prefer less sedating drugs, such as carbamazepine, phenytoin, or valproate. The prophylactic use of phenobarbital in infants with febrile seizures has been challenged. Phenobarbital also is useful in seizures caused by barbiturate withdrawal in dependent individuals. The sodium salt is administered parenterally as part of the treatment regimen for status epilepticus.
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