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Phenytoin, total
| Item | Value | ||
|---|---|---|---|
| Test Update Information | Phenytoin assay changed from the Abbott Axsym method to the Beckman DxC method on 09/20/2012. | ||
| Approval req'd? | No | ||
| Available Stat? | Yes | ||
| Test code | PHNY | ||
| Test group | Phenytoin | ||
| Performed by | Parnassus Chemistry | ||
| In House Availability | Test available 24 hours per day 7 days per week | ||
| Method | Turbidimetric inhibition immunoassay (Beckman DxC800) | ||
| Collection Instructions | Time to steady state: 3-4 days Collect samples 30 minutes before AM dose. Draw at least 4 hours post-IV dose and 6-9 hours post-PO dose Indicate time of draw on requisition. |
||
| Container type | Red top | ||
| Amount to Collect | 1 mL blood | ||
| Sample type | Serum | ||
| Preferred volume | 0.5 mL serum | ||
| Min. Volume | 0.2 mL serum | ||
| UCSF Rejection Criteria | Specimen received in gold top or lithium heparin tube with gel | ||
| Units | mg/L | ||
| Normal range |
Source: Phenytoin: Drug information, Copyright 1978-2012 Lexicomp, Inc. Accessed in UpToDate, August 2012 Therapeutic ranges adopted or modified from the literature based on recommendations of UCSF Pharmacists |
||
| Critical value | > 30 mg/L | ||
| Synonyms | Dilantin; Fosphenytoin; Cerebyx | ||
| Stability | Room temperature 8 hours, refrigerated 2 days, frozen at -20C 1 week | ||
| Turn around times | STAT 1 hour, Routine 4 hours | ||
| Additional information | The level of phenytoin can be empirically corrected for the effect of hypoalbuminemia with the formula: Corrected = Measured/(0.9(actual albumin/4.4) + 0.1) OR Corrected = Measured/(0.2 x actual albumin) + 0.1). If renal failure coexists with hypoalbuminemia, the formula is: Corrected = Measured/(0.9)((0.48 x actual albumin/4.4) + 0.1) OR Corrected = Measured/(0.1 x actual albumin) + 0.1) Click here for A guide on Drug Level Monitoring |
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| LOINC code | 3968-5 | ||
| Last Updated | 1/23/2013 3:48:52 PM | ||
| Entry Number | 737 |
If you have additional questions regarding this test, please call: 415-353-1667