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UW Health SMPH
American Family Children's Hospital

UW Hospital and Clinics Lab Test Directory

Test Name: Valproate, Unbound

Test Code(s): UVATE / HCUVATE

CPT Code(s): 80164, 80165

Test Description: Test Component:

Total and unbound (free) valproic acid.

Methodology: Gas Chromatography

Clinical Significance: Anticonvulsant

Days Performed: Daily, dayshift- unbound level is not available after hours.

Turnaround Time: Stat: 2 hours.
Routine: 24 hours.

Specimen Requirements

Specimen: Blood

Collection Container: Preferred: Red top

Collection Volume: Preferred: 9 mL
Pediatrics: 3 mL

Sample Analyzed: Serum

Volume Required: Preferred: 2 mL
Pediatrics: 1 mL

Specimen Processing: Centrifuge. Transfer cell-free serum to  plastic vial. Refrigerate.

Specimen Transport: Transport specimen to UWHC Core Laboratory (B4/220). Transport with coolant pack if coming from outreach location.

Unacceptable Criteria: Specimens collected in red cap with yellow ring (SST) tubes are not acceptable.

Stability: Ambient: 12 hours
Refrigerated: 48 hours
Frozen: 1 year


Interpretive Guidelines:

The therapeutic range for unbound valproate has not been established. The free fraction should be 7-15% when the total valproate is 50-100 mcg/mL, and 22-30% when the total is 125-150 mcg/mL.

Critical Calls: View

Additional Information:

Protein binding of valproic acid is concentration dependent. Albumin sites will be saturated, in most individuals, when the total valproic acid level is near 100 mcg/mL. Any increase in dose will markedly increase the free drug level. The free fraction will increase in the presence of hypoalbuminemia. Free fatty acids may cause increased free valproate fraction.


This test was developed and its performance characteristics determined by the UWHC Clinical Laboratories.  This test meets the standards for clinical testing.  This test should not be regarded as investigational or for research use.  The US Food and Drug Administration (FDA) has not approved or cleared this test; however, the FDA has determined that such clearance or approval is not necessary.

Free Valproate Depakote Depakene VALPROIC ACID

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