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HelpTest Code LAB31 Phenytoin Level
Clinical System Name
Phenytoin Level
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.
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 |
Performing Laboratory
Seattle Children's Laboratory
Department
Department: Core Chemistry
Phone Number: 206-987-2617 (Client Services)
Synonyms
Cerebyx
Dilantin
Diphenylhydantoin
DPH
Fosphenytoin
Phenytoin
LAB31
Availability
| STAT | Performed | TAT |
|---|---|---|
| Y | 24/7 | 1 h |
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 |
CPT Codes
80185
Critical Values
≥ 25 uG/mL