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Test Code VALP Valproic Acid (Depakane®) Level, Total, LAB24


Turbidimetric Inhibition Immunoassay

Performing Laboratory

St. Luke's Hospital Cedar Rapids

Specimen Requirements


Preferred: Green-top (lithium heparin) tube

Acceptable: Gold-top serum gel tube or plain red-top tube

Specimen Volume: 0.1 mL of plasma or serum

Stability: Separated specimens should be analyzed immediately or are stable for

              2 hours at 20 – 25 °C, 8 hours at 2 – 8 °C. For longer storage, samples may

              be frozen at -20 °C for up to 2 months.  Thawed samples should not be refrozen.

Collection Instructions: Peak level is reached 30 minutes to 1 hour after dosing with syrup,

              30 minutes to 2 hours after dosing with capsules or plain tablets, and 3 to 8 hours

              after dosing with enteric coated tablets. Trough level should be drawn immediately

              prior to next dose.

Note: 1. Valproic acid time to steady state is 2 to 4 days of chronic oral dosing.

          2. Levels may be ordered at any time toxicity is suspected.


Reference Values

Therapeutic range: 50-100 mcg/mL

Critical values

Pediatric: >150 mcg/mL

Adult: >200 mcg/mL

Day(s) Test Set Up

Monday through Sunday

Test Classification and CPT Coding


Useful For

Valproic acid is a broad-spectrum anticonvulsant drug used solely or in combination with other anticonvulsant drugs for the treatment of absence seizures.


Due to great individual differences in dosage requirements to achieve efficacious therapy, determinations of valproic acid serum concentrations are required to direct effective therapy.