Laboratory: Clinical Biochemistry
Test Name:
VALPROIC ACID, TOTAL AND FREE - (S)
Test Code: MISC
Clinical Information:
Test Indications:
This test is used for monitoring both total and free valproic acid in patients with renal failure or during concomitant therapy with other drugs that are also highly protein-bound (e.g. phenytoin).
In uremia, or during therapy with other protein-bound drugs (e.g. phenytoin), valproic acid is displaced from protein, resulting in a higher free fraction of circulating drug. Neurologic activity and toxicity are directly related to the free fraction. As a result, measurement of free valproic acid level is the best indicator to determine adequate therapeutic level or toxicity.
Must be approved by a Clinical Chemist prior to sendout.
Click here for the Approval for Test Referral Biochemistry form (F260-11-02)
Send referral request form and a test requisition specifying Valproic Acid, Total and Free to be sent to Mayo Laboratories. Do not use the valproic acid check box on the requisition.  
Collection Devices:
Specimen Required:
Serum: 2.0 mL
Pediatric Serum: 2.0 mL

Centrifuge and aliquot within 2 hours of collection
Stability 14 days refrigerated, 28 days frozen
Referral:
Serum: 2.0 mL

Store and ship frozen
Requisition:
Reference Values:
A descriptive report will be sent
Availability:
Within 1 Week
See Also:
More Information:
Store and ship frozen to Mayo Medical Laboratories
Test ID: VALPG