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|Method||Ultrafiltration-High Pressure Liquid Chromatography|
|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
Collect in Red top tube only. Avoid hemolysis.
Order total phenytoin separately if desired. Indicate time of collection on requiisition.
|Container type||Red top (Gold top NOT acceptable)|
|Amount to Collect||5 mL blood|
|Preferred volume||2.5 mL serum|
|Min. Volume||1.5 mL serum|
|UCSF Rejection Criteria||Collected in Gold top. Gross hemolysis|
|Processing notes||Refrigerate separated serum. Be sure that total Phenytoin has been separately ordered, if requested. Order Quest # 39693P
For B&T patients order labCorp test #070706 "Phenytoin Free & Total only"
|Synonyms||Dilantin; Fosphenytoin; Cerebyx|
|Stability||Room temperature 4 days, refrigerated 1 week, frozen at -20C 1 month|
|Turn around times||Run 5x per week. Turnaround 3-5 days|
|Additional information||Phenytoin binds to albumin, only the free fraction is therapeutically active. In patients with hypoalbuminemia, who are on dialysis, are critically ill or are receiving medications that may displace phenytoin the measurement of total phenytoin levels may result in either under or overdosing. In these situations assessing free phenytoin is suggested.|
|Last Updated||10/28/2013 11:49:04 AM|