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HelpTest Code LAB31 Phenytoin Level
Clinical System Name
Phenytoin Level
Synonyms
Cerebyx
Dilantin
Diphenylhydantoin
DPH
Fosphenytoin
Phenytoin
LAB31
Sample Requirements
Specimen: Whole Blood
Container(s): Lt. Green/Mint Top Lithium Heparin, Lt. Green/Lithium Heparin Microtainer, Gold SST, Gold Microtainer, Dark Green/Sodium Heparin, Red
Preferred Vol: 1.0 mL
Minimum Vol: 0.5 mL
Note: Draw specimen just before next dose. Avoid hemolysis. This test is a total Phenytoin (Dilantin). Free Phenytoin requires 6 mL blood; if ordered, both the free and total will be performed at Harborview with a turn-around time of 1 - 3 days.
Processing Instructions
Reject due to: Hemolysis, age of specimen, incorrect collection container.
Spin: Y
Aliquot: Y
Storage location: Core Chemistry Refrigerator
Off-site collection: Draw specimen just before next dose. Avoid hemolysis. Specimen should be centrifuged within 2 hours of collection. Spin blood and transfer serum or plasma to plastic tube and refrigerate or freeze.
Stability
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum or Plasma | RT |
≤ 8 h |
| Serum or Plasma | 2-8 C |
≤ 7 d |
| Serum or Plasma | -20 C or -70 C |
≤ 12 w |
Availability
| STAT | Performed | TAT |
|---|---|---|
| Y | 24/7 | 1 h |
Performing Laboratory
Seattle Children's Laboratory
Department
Department: Core Chemistry
Phone Number: 206-987-2617 (Client Services)
CPT Codes
80185
Methodology
Method: Immunoassay method by Vitros 4600
Analytical Volume: 0.02 mL + 0.03 mL dead space
Method is affected by EDTA & hemolysis.
Reference Range
| uG/mL | |
| Therapeutic | 10 - 20 |
| Toxic |
≥ 25 |
Critical Values
≥ 25 uG/mL
Description
Phenytoin is a widely prescribed anticonvulsant drug used in the treatment of generalized and partial seizures. Phenytoin measurements are used to monitor patient compliance and therapy and to diagnose potential overdose.