Measuring Depakote (Valproic Acid) Levels
The test that measures Depakote levels is a serum valproic acid concentration test, which should be drawn as a trough level (immediately before the next dose) to assess therapeutic drug monitoring.
Test Specifications
Primary Laboratory Test
- Serum valproic acid concentration is the standard test for measuring Depakote levels in clinical practice
- The sample should be obtained as a trough level (drawn immediately before the next scheduled dose) for accurate therapeutic monitoring
- Therapeutic range is typically 50-100 mcg/mL for seizure disorders, though target ranges may vary by indication
When to Order Testing
- Initial dosing: Check levels 2-4 days after starting therapy or after dose changes (once steady state is reached)
- Routine monitoring: Periodically during maintenance therapy, especially if:
- Seizure control is inadequate
- Signs of toxicity appear (tremor, sedation, confusion, ataxia)
- Drug interactions are introduced
- Hepatic function changes
- Pregnancy occurs (requires more frequent monitoring)
Additional Monitoring Parameters
- Liver function tests (AST, ALT, bilirubin): Essential before starting therapy and periodically during treatment, as valproic acid can cause hepatotoxicity
- Complete blood count with platelets: Valproic acid can cause thrombocytopenia and other hematologic abnormalities
- Ammonia level: If encephalopathy symptoms develop, as hyperammonemia can occur even with therapeutic valproic acid levels
- Free (unbound) valproic acid: May be useful in patients with hypoalbuminemia, renal failure, or pregnancy, as these conditions alter protein binding
Clinical Interpretation Considerations
- Valproic acid is highly protein-bound (80-95%), so conditions affecting albumin levels will impact total drug concentrations
- The relationship between serum concentration and clinical effect is not always linear
- Some patients achieve seizure control at levels below or above the standard therapeutic range
- Toxicity can occur within the therapeutic range in susceptible individuals