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HelpPhenytoin Level Total and Free
eD-H Order Code
LAB176
Specimen Collection Information
| Specimen | Minimum Test Volume | Container | Special Handling |
|---|---|---|---|
| Blood | 0.5 ML |
Specimen Transport Temperature
Refrigerated
Reference Ranges / Critical Values
| Assay | Gender | Age Range | Normal Range | Critical Values | Units |
|---|---|---|---|---|---|
| Phenyt Free % | All | 0 Minutes – 150 Years | 8 -12 | % | |
| Phenytoin Free | All | 0 Minutes – 150 Years | 1.00 -2.00 | >3.00 | mg/L |
| Phenytoin Total | All | 0 Minutes – 150 Years | 10.0 -20.0 | >25.0 | mg/L |
Specimen Stability
Additional Specimen Instructions
Free phenytoin testing is not indicated for subtherapeutic total phenytoin level <6.0 mg/L. Testing will not be performed if ordered more than once per calendar day.
Interpretive Data
| Assay Display | Interpretive Data |
|---|---|
| Phenyt Free % | This test was developed and its performance characteristics determined by Dartmouth-Hitchcock Med Ctr. It has not been cleared or approved by the FDA. The laboratory is regulated under CLIA as qualified to perform high-complexity testing. This test is used for clinical purposes. It should not be regarded as investigational or for research. |
| Phenytoin Free |
Therapeutic range: Free phenytoin: 1.00-2.00 mg/L % Free phenytoin: 8-12% Toxic range: Free phenytoin: >3.00 mg/L This test has not been cleared by the US FDA. Performance characteristics of this test were determined by Dartmouth-Hitchcock Medical Center in accordance with CLIA requirements. This laboratory is qualified under CLIA to perform high-complexity testing. |
| Phenytoin Total | Patients with renal dysfunction (e.g. creatinine clearance < 30 mL/min) may show falsely elevated results due to accumulation of metabolites in renal failure. |
Day(s) Performed
Monday through Sunday; 10AM through 8PM
Performing Lab Section
Chemistry