Phenytoin
CPT Code(s):
80186
Turnaround Time:
4 hours
Specimen Requirements
Preferred Specimen:
Serum
Minimum Volume:
1.0 mL
Transport Container:
Red Top Tube
Transport Temperature:
Room Temperature
Collection Instructions:
Allow blood to clot completely prior to centrifugation. Separate serum from cells within 45 minutes of collection.
Rejection Criteria:
Citrate, Fluoride,Sodium Heparin, or EDTA plasma specimen; specimen received on red cells gross hemolysis; lipemia; improper labeling
Stability Criteria
Room Temperature:
24 hours
Refrigerated:
48 hours
Frozen:
30 days
Clinical Significance
Phenytoin is clinically significant and diagnostically useful in measuring the levels of Phenytoin, an antiepileptic medication, in a patient's bloodstream. Phenytoin is commonly prescribed to treat seizures and epilepsy.
The specific clinical significance and diagnostic use of Phenytoin include:
1. Therapeutic Drug Monitoring: Phenytoin has a narrow therapeutic range, and monitoring its concentration helps healthcare providers ensure the medication's effectiveness and safety. The test is used to assess if the patient's Phenytoin levels are within the desired therapeutic range to control seizures effectively.
2. Dose Optimization: The quantitative results from Phenytoin guide healthcare providers in adjusting the dosage regimen to achieve the optimal therapeutic level. Individuals may have varying rates of metabolism, and the test helps personalize the dosage to achieve the desired therapeutic effect while minimizing side effects.
3. Treatment Compliance Monitoring: The test can confirm the presence of Phenytoin in a patient's system, indicating compliance with the prescribed treatment regimen. It helps healthcare providers assess if the patient is taking the medication as prescribed and identify any non-compliance or deviations from the prescribed dosage.
4. Identification of Toxicity: Monitoring Phenytoin levels helps identify potential toxicity or overdose. High levels of Phenytoin can lead to adverse effects such as dizziness, confusion, and tremors. The test enables healthcare providers to detect elevated levels and adjust the dosage accordingly to prevent toxicity.
5. Pharmacokinetic Studies: Phenytoin contributes to understanding Phenytoin's metabolism, distribution, and elimination in different patient populations. This knowledge aids in developing dosing guidelines, particularly in specific populations such as children, pregnant women, or patients with renal or hepatic impairment.
6. Drug Interactions: Phenytoin can interact with other medications, affecting its levels in the body. The test helps identify potential drug interactions and guide healthcare providers in adjusting the Phenytoin dosage or considering alternative treatment options.
Overall, Phenytoin plays a crucial role in therapeutic drug monitoring, optimizing dosage regimens, ensuring treatment compliance, identifying toxicity, and understanding Phenytoin's pharmacokinetics. It enhances the management of seizures and epilepsy by tailoring the medication dosage to individual patients, minimizing side effects, and ensuring optimal therapeutic outcomes. Collaborative efforts between healthcare providers and laboratory professionals are vital in interpreting the test results accurately and providing appropriate patient care.