Phenytoin Level, Grand Itasca


Sunquest Code:GHPHYT  
Epic Code:LAB7043Epic Name:Phenytoin GH
Synonyms:Dilantin; Diphenylhydantoin; Fosphenytoin; PHYT
Methodology:Homogenous enzyme immunoassay
Turnaround Time:Performed and reported 24 hours/day.


Collection Instructions

Specimen:Blood
Optimal Volume:2.5 mL
Minimum\Peds Volume:0.6 mL
Container:Green (lithium heparin, gel) (Red (no gel), Red or gold (gel))
Collection Instructions:Trough level is preferred; collect immediately before dose. It is advisable to monitor at the same time in the dosing schedule. Collect peak level 1.5-3 hours after solid dosage (rapid dissolution) formulation or 3-9 hours after extended dissolution.
Causes for Rejection:Collected in a purple (EDTA) tube.
Contraindications:Fosphenytoin, a phosphate ester of phenytoin, cross-reacts with this assay. Samples from patients receiving fosphenytoin should be collected at least 2 hours following IV administration, or 4 hours following IM administration. Phenytoin levels measured before complete conversion of fosphenytoin will not reflect phenytoin concentrations ultimately achieved. Fosphenytoin is measured as total phenytoin. Order PHYT with comment "Fosphenytoin".


Processing and Shipping

Specimen Processing:Centrifuge and transfer serum/plasma within 2 hours of collection. Aliquot 1.25 mL, 0.3 mL minimum. Store in refrigerator.
Shipping Instructions:Ship at refrigerated temperature.
Test Performed at or Referral Lab Chemistry  (Grand Itasca GICH)


Interpretive

Critical Range:Greater than 30.0 ug/mL
Reference Range:10-20 ug/mL
Use:Monitor therapeutic dosing and evaluate toxicity. Half-life is 8-60 h.


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