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Valproic Acid
Test Code916
CPT Codes
80164
Preferred Specimen
1 mL serum collected in a red-top tube (no gel)
Patient Preparation
Collect as a trough just prior to next dose
Minimum Volume
0.2 mL
Other Acceptable Specimens
Plasma collected in: EDTA (lavender-top), sodium heparin (green-top), lithium heparin (green-top), sodium fluoride or potassium oxalate (gray-top), or 3.2% sodium citrate (light blue-top) tube
Instructions
Do not use gel barrier tubes. Centrifuge and immediately separate serum or plasma specimens from the cells into clean, plastic, screw-cap vial(s). Do not use serum separator tubes. Submission of a serum separator tube will result in cancellation.
Transport Temperature
Room temperature
Specimen Stability
Room temperature: 5 days
Refrigerated: 7 days
Frozen: 30 days
Refrigerated: 7 days
Frozen: 30 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Serum Separator Tube (SST®)
Methodology
Immunoassay (IA)
Setup Schedule
Set up: Mon-Sat; Report available: Next day
Clinical Significance
Valproic acid is used as an anticonvulsant to treat certain types of seizures, to prevent migraine headaches and to treat various psychiatric illnesses such as bipolar disorder and aggression. Drugs that compete for protein-binding sites with valproic acid can increase the concentration of valproic acid. Therapeutic drug monitoring is useful to optimize dose. Measurement of the free concentration is useful if toxicity is suspected.
