Valproic Acid, Total, Serum
Use
This test is useful for monitoring total valproic acid levels in patients undergoing therapy, assessing their compliance with prescribed regimens, and evaluating potential toxicity. Valproic acid is used as a medication for controlling absence seizures, generalized tonic-clonic seizures, and partial seizures, either as a stand-alone treatment or in conjunction with other antiepileptic drugs. Monitoring is crucial because valproic acid levels can significantly impact the drug's pharmacology—especially in relation to concurrent medications such as phenytoin.
Special Instructions
Valproic acid has a known interaction profile with drugs such as phenytoin, requiring careful interpretation of levels. The specimen should be collected in a serum gel tube or a red-top tube and processed within 2 hours. Valproic acid monitoring is particularly critical during the first 6 months of therapy due to the potential for hepatic dysfunction and other side effects.
Limitations
The test does not directly measure free valproic acid levels, which might be needed to fully assess potential toxicity causes when total concentrations appear non-excessive. Therapeutic levels may fluctuate considerably depending on numerous factors including medication timing, which requires careful interpretation of results in a clinical context. Monitoring of liver function is essential due to risks of hepatic failure, particularly at therapeutic levels that exceed recommended ranges.
FDA ApprovedNew York Approved
Methodology
Immunoassay
Biomarkers
LOINC Codes
- 4086-5
- 4086-5
Result Turnaround Time
1-2 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
0.5 mL
Minimum Volume
0.25 mL
Container
Serum gel or red top tube, submit in plastic vial
Collection Instructions
Serum gel tubes should be centrifuged within 2 hours of collection. Red-top tubes should be centrifuged and serum aliquoted into a plastic vial within 2 hours of collection.
Causes for Rejection
Gross hemolysis
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 72 hours |
| Refrigerated | 14 days |
| Frozen | 28 days |