Valproic Acid, Free and Total, Serum

Valproic Acid, Free and Total

Order Code:	VPAFT
Epic Lab Code:	LAB172
Order Form:	A-1a Miscellaneous Request or Epic Req

Commercial Mail-out Laboratory
01250 PFP
356-3527

Specimen:

Serum

Collection Medium:

Red top tube

Minimum:

Preferred Minimum: 2 mL serum
Absolute Minimum: 1 mL serum

Rejection Criteria:

Citrated plasma. Tubes that contain liquid anticoagulant.

Delivery Instructions:

Deliver to laboratory immediately after collection.

Specimen Instructions:

Separate serum from cells within 2 hours of collection.

Turn Around Time:

4 working days upon receipt at reference laboratory

Reference Range:

Valproic Acid, Total Therapeutic Range: 50-125 μg/mL Toxic: Greater than 150 μg/mL Valproic Acid, Free Therapeutic Range: 6-22 μg/mL Toxic: Greater than 50 μg/mL VPA- % Free 5-18%

Interpretive Data:

Free valproic acid may be important to monitor in patients with altered or unpredictable protein binding capacity because valproic acid exhibits variable, dose-dependent protein binding. Valproic acid is also subject to drug-drug interactions due to displacement of protein binding. Calculating percent free attempts to minimize differences in test cross-reactivity and may be useful in dose optimization.

Methodology:

Immunoassay

CPT Code:

80164 X2