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Test Code PTN Phenytoin (Dilantin), Total, Plasma or Serum

Methodology

Used for therapeutic drug monitoring. Phenytoin is the most widely used anticonvulsant. It is effective against grand mal and the generalized spread of seizures with focal origin.

Performing Laboratory

St. Mary's Regional Medical Center-Chemistry

 

CPT: 80185

Specimen Requirements

Submit one of the following:

 

Plasma

Container/Tube: Light green-top (lithium heparin) tube

Specimen: 1 mL of lithium heparin plasma
Transport Temperature: Ambient
Collection Instructions: Draw specimen just prior to administration of next dose for therapeutic response.
Note: 1. Indicate plasma.
           2. Label specimen appropriately (plasma).

 

Serum

Container/Tube: Plain red top or gold serum gel tube

Specimen: 1 mL of serum
Transport Temperature: Ambient
Collection Instructions: Draw specimen just prior to administration of next dose for therapeutic response.
Note: 1. Indicate plasma.
2. Label specimen appropriately (serum).


 

Reference Values

Therapeutic concentration: 10-20 mcg/mL

Potentially toxic concentration: >30 mcg/mL

Call criteria (automatic call-back): >25 mcg/mL

Day(s) Test Set Up

Monday through Sunday