Specimen Requirements


Valproic Acid, Free

Specimen Requirement

1 Red Top/3.0 mL serum. Centrifuge, separate and refrigerate. Do not collect in SST tube.

Alternate specimen: lavender EDTA


Ultrafiltrate assayed by liquid chromatography/tandem mass spectrometry (LC/MS-MS)


Room temp: 14 days, Refrigerated: 14 days, Frozen: 14 days

Reference Range

By Report*


2-4 days

Clinical Use

Analysis of Free Valproic Acid levels may be useful in delineating the cause of toxicity when the total concentration is not excessive. Geriatric patients often exhibit hypoalbuminemia, which results in a marked decrease in protein-binding sites for drugs. The clinical symptoms of drug intoxication may not be apparent, but may manifest themselves in impaired cognitive function and confusion. Therefore, it is important to evaluate both total and free concentrations.

Test Code