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Specimen Collection Manual and Test Catalog

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PHENYTOIN LEVEL

Geisinger Epic Procedure Code:  LAB2844    Geisinger Epic ID:  6356

SPECIMEN COLLECTION
Specimen type: 

Serum or plasma


Preferred collection container: 
Alternate collection container: 
3.5 mL gold-top (serum separator) tube
3 mL green/yellow-top (plasma separator) tube
Specimen required: 

2 mL serum or plasma; minimum 0.2 mL.


Special notes: 

See specimen processing instructions.


Patient preparation: 

Collect just prior to next dose.



SPECIMEN PROCESSING
Processing instructions: 

Allow serum to clot. Centrifuge to separate serum or plasma within 2 hours of collection. Specimens in SST or PST must be aliquoted within 24 hours of collection.


Transport temperature: 

Refrigerated (preferred) or frozen.


Specimen stability: 

Room temperature: 4 days. Refrigerated: 4 days. Frozen: 1 month.


Rejection criteria: 

Specimens in SST or PST not aliquoted within 24 hours of collection.



TEST DETAILS
Reference interval: 

Therapeutic Range: 10-20 mcg/mL.


Critical values/courtesy alerts: 
Above 30 mcg/mL.
Additional information: 

Significant interference with this procedure may occur in patients with antibodies induced during treatment with mouse monoclonal antibodies.


CPT code(s):  80185
Note: The billing party has sole responsibility for CPT coding.  Any questions regarding coding should be directed to the payer being billed.
The CPT codes provided by GML are based on AMA guidelines and are for informational purposes only.

Methodology: 
Immunoassay
Synonyms: 

Dilantin, PHNY


Clinical significance: 

Phenytoin is an anticonvulsant hydantoin used for the treatment of generalized grand mal and complex partial seizures. Phenytoin is also used in neurosurgical procedures. Phenytoin levels are monitored to assure adequate theraepeutic levels are achieved and to avoid toxicity.


Doctoral Director(s): 
Hoi-Ying Elsie Yu, PhD, DABCC, FADLM
Sheng-Ying (Margaret) Lo, PhD, DABCC
Review Date:  12/27/2024

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