Phenytoin (Epanutin) analysis in serum is a test used to measure phenytoin levels in the blood. Phenytoin is an anticonvulsant commonly used to treat seizures. This test is an essential tool for monitoring treatment effectiveness, helping doctors adjust the appropriate dose and avoid toxicity from high drug levels. A blood sample is collected and analyzed in a specialized laboratory, providing an accurate assessment of phenytoin levels in the body. It is recommended to perform this test periodically for patients on long-term phenytoin therapy, especially at the beginning of treatment or when changing the dose, to ensure effective condition management and reduce potential risks.