A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # |
Phenytoin, Free : 3189
Test CodePTNFQ or 3189
Alias/See Also
Dilantin
CPT Codes
80186
Instructions
Collect as a trough just prior to next dose. For patients receiving fosphenytoin therapy, collect as peak (at least 2 hours after IV infusion or at least 4 hours after IM injection).
Transport Container
Preferred Specimen
2.5 mL serum collected in a red-top tube (no gel)
Minimum Volume
1 mL
2.5 mL serum collected in a red-top tube (no gel)
Minimum Volume
1 mL
Transport Temperature
Refrigerated.
Specimen Stability
Room temperature: 4 days; Refrigerated: 7 days; Frozen: 30 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Specimen received in Serum Separator Tube (SST®); Plasma
Methodology
Ultrafiltration/Immunoassay
Setup Schedule
Monday - Saturday
Report Available
1 day (From receipt at performing laboratory)
Reference Range
1.0-2.0 mg/L
Clinical Significance
Phenytoin is used singly or in combination with other anticonvulsants to treat grand mal epilepsy. Monitoring the serum levels of antiepileptic drugs has increased the efficiency and safety of drug therapy in epilepsy. It facilitates individualization of dosage regimen, reveals irregular drug intake and identifies the responsible agent in intoxicated patients on multiple drug therapy. Free phenytoin is especially useful in patients with altered phenytoin binding to protein, e.g., uremia or individuals having abnormally low levels of albumin, such as nephrotic syndrome. Free phenytoin in serum correlates better with the various other free compartments of the body than does the total drug and is probably a better estimate of the "active drug level" at the receptor site and agrees more with the clinical response.
Performing Laboratory
Quest Diagnostics