Phenytoin (DPH, Epanutin)

Code

4835

Principle

Phenytoin (Dilantin) is one of the most widely prescribed anticonvulsants and is occasionally used as a myocardial antiarrhythmic. In the treatment of epilepsy, phenytoin is indicated for grand mal epilepsy (major motor) and cortical focal seizures and temporal lobe epilepsy.

Preanalytical

1 mL Serum Refrigerated

Turn Around Time

1 day

Methodology

Chemiluminescent immunoassay (CLIA)

Limitations

Samples from patients receiving fosphenytoin should be drawn at least 2 hours following IV administration and 4 hours following IM administration. Phenytoin concentrations measured before complete conversion of fosphenytoin will not reflect phenytoin concentrations ultimately achieved.

Heterophilic antibodies in human serum can react with immunoglobulins, interfering with in vitro immunoassays. Patients routinely exposed to animals or to animal serum products can be prone to this immunoglobulins interference, and anomalous values may be observed. Additional information may be required for diagnosis. Specimens from patients who have received preparations of mouse monoclonal antibodies for diagnosis or therapy may contain human anti-mouse antibodies (HAMA). Specimens containing HAMA may produce anomalous values when tested