Mar 25, 2015




Clinical Hub,Tools & Resources,UWHC Lab Test Directory,Toxicology

Valproate, Unbound

Valproate, Unbound (HCUVATE) Toxicology Lab Test

Name: Valproate, Unbound

Test Name: Valproate, Unbound

Health Link Test Code: HCUVATE

LIS Test Code: UVATE

CPT Code(s): 80164, 80165

Test Component:

Total and unbound (free) valproic acid.

Methodology: Gas Chromatography

Clinical Information:


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

In-Lab Turnaround Time: 1 day.

Stat In-Lab Turnaround Time: 2 hours.

Specimen: Blood

Collection Container: Red top

Collection Volume: 9 mL

Pediatric Collection Volume: 3 mL

Stability Ambient:

12 hours

Stability Refridgerated:

48 hours

Stability Frozen:

1 year

Sample Analyzed: Serum

Testing Volume: 2 mL

Pediatric Testing Volume: 1 mL

Specimen Processing:

Centrifuge. Transfer cell-free serum to plastic vial. Refrigerate.

Specimen Transport:

Transport specimen to laboratory. Transport with coolant pack if coming from clinic location.

Unacceptable Criteria:

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


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.

Interpretation Type: Interpretive Guidelines

Critical Calls: yes

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.