Phenobarbital, Confirmation
CPT Code(s):
80345
Turnaround Time:
24 - 72 hours
Specimen Requirements
Preferred Specimen:
Urine
Minimum Volume:
1.0 mL
Transport Container:
Yellow Top Tube or Sterile Cup
Transport Temperature:
Room Temperature
Collection Instructions:
Collect urine in plastic container and transfer to plain yellow top tube (without preservative).
Rejection Criteria:
Specimen received outside stability requirements; Excessive blood, particulates, viscosity present
Stability Criteria
Room Temperature:
24 hours
Refrigerated:
7 days
Frozen:
30 days
Clinical Significance
Phenobarbital with quantitative results, using liquid chromatography-tandem mass spectrometry (LC/MS-MS), is clinically significant and diagnostically useful in detecting and measuring the levels of phenobarbital in a patient's system. Phenobarbital is a barbiturate medication commonly prescribed for the treatment of seizures, epilepsy, and certain sleep disorders.
The specific clinical significance and diagnostic use of Phenobarbital include:
1. Therapeutic Drug Monitoring: Phenobarbital has a narrow therapeutic range, meaning that maintaining the drug's concentration within a specific range is crucial for optimal treatment outcomes. The quantitative results from the test help healthcare providers monitor the levels of phenobarbital in the patient's blood or other biological samples, ensuring that the drug concentration remains within the therapeutic range.
2. Treatment Optimization: By measuring phenobarbital levels, healthcare providers can assess the patient's response to the medication and adjust the dosage accordingly. Monitoring the drug's concentration helps optimize the treatment regimen to achieve optimal seizure control or management of sleep disorders while minimizing potential side effects.
3. Compliance Monitoring: The test is used to assess patient compliance with phenobarbital therapy. Low or undetectable levels of phenobarbital may indicate non-adherence to the prescribed treatment regimen, which can lead to suboptimal seizure control or treatment failure.
4. Toxicity Assessment: Elevated levels of phenobarbital can indicate potential toxicity. The quantitative results of the test can help identify patients at risk of phenobarbital overdose or toxicity, allowing for prompt intervention and dose adjustments to prevent adverse effects.
5. Forensic and Medicolegal Investigations: Phenobarbital using LC/MS-MS has forensic applications, providing evidence of phenobarbital use or exposure in legal and criminal investigations. It can be useful in cases involving suspected drug-facilitated crimes or accidents.
6. Research and Pharmacokinetics: The test is valuable in research studies and pharmacokinetic investigations, contributing to a better understanding of phenobarbital's metabolism, distribution, and elimination in different patient populations or under specific conditions. This information helps in the development of dosing guidelines and treatment strategies.
The use of LC/MS-MS in Phenobarbital enables accurate and precise measurement of phenobarbital levels, enhancing the clinical interpretation and decision-making process.
In summary, Phenobarbital with quantitative results using LC/MS-MS is clinically significant in therapeutic drug monitoring, treatment optimization, compliance monitoring, and toxicity assessment. It plays a crucial role in managing patients on phenobarbital therapy, ensuring optimal drug concentrations for effective treatment while minimizing the risk of adverse effects. The test also has forensic and research applications, contributing to the understanding of phenobarbital's pharmacokinetics and aiding in legal investigations when necessary. Collaborative efforts between healthcare providers and laboratory professionals are essential in interpreting the test results accurately and providing appropriate patient care.