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Laboratory: Clinical Biochemistry  (AUTOMATED)
Test Name:
VALPROIC ACID (Alternate Name(s): Valproate, Depakote, Depakene) - (P) and (S)
Test Code: VALP
Clinical Information:
Valproic acid is an anticonvulsive and mood stabilizer medication. It is measured to monitor therapeutic levels and to evaluate toxicity.
Collection Devices:
Gel tubes are not acceptable.
Specimen Required:

Plasma: 1.5 mL
Pediatric Plasma: 1.0 mL

Trough measurements are recommended (within 30 minutes before next dose).
Plasma or serum NO GEL are acceptable.

Allow serum specimen to clot completely at room temperature to ensure complete clot formation has taken place prior to centrifugation. Centrifuge and aliquot within 2 hours of collection.
Specimen Stability: 14 days refrigerated, 28 days frozen.

Samples must be transferred to an aliquot tube and stored frozen if analysis will not be complete within 48 hours (#110-10-05 Serum / Plasma Separation Procedure & Transport)
Reference Values:
Total Valproic Acid
Therapeutic:  50-100 mg/L (350-700 µmol/L)
Toxic:             >120 mg/L  (>830 µmol/L)

Free Valproic Acid
Therapeutic:  5-10 mg/L (35-70 µmol/L)
Toxic:            >10 mg/L (>70 µmol/L)

Method of Analysis: Homogeneous enzyme (G6PDH) immunoassay (Roche Cobas, Ortho Vitros)
Stat or Routine
See Also:
More Information:
Interpretation & Assay Interferences:
Half-life: 12-16 hours
Time to steady state: 2-3 days