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HelpTest Code LAB24 Valproic Acid Level, Blood
Performing Laboratory
St. Louis Children's Hospital - Chemistry
Specimen Requirements
Patient Preparation: Fasting preferred but not required
Container/Tube
Preferred: Mint green-top Lithium Heparin (MNTGRN LiHep) tube
Acceptable: Green samplette/microtainer, plain red-top tube, Lavender-top (EDTA) tube, or Gold SST gel tube
Collection Volume: 1.0 mL (minimum 0.6 mL)
Submission Container/Tube: If specimen is coming from outside facility and collected in a microtainer, Lavender-top (EDTA) tube, or plain red-top tube aliquot processed sample into a plastic vial for transport (labeling with specimen type).
Special Instructions: Specimen should be collected just prior to next dose.
Sample Rejection
Mislabeled or unlabeled specimens
Logistics
Test Availability: Monday-Sunday
Cut-off time: None; performed as received
Turnaround Time: Same day; 2 hours from receipt in lab
Reference Values
Therapeutic Range: 50-100 mct/mL
Critical Values: >150 mcg/mL
Critical test results will be automatically called back initially and every 24 hours thereafter.
Methodology
Enzymatic Competitive Immunoassay
Limitations
- In very rare cases, gammopathy, in particular type IgM (Waldenstrom's macroglobulinemia), may cause unreliable results.
Additional Information
FOR SLCH CORE LABORATORY USE ONLY
Lab Processing Instructions: Centrifuge specimen to separate. If specimen is collected in a plain red-top tube, microtainer, or Lavender-top (EDTA) tube aliquot sample into a Roche false-bottom tube for testing (labeling with specimen type).
Processed Volume: 0.3 mL plasma/serum
Analyte Stability:
| Specimen Type | Temperature | Time | |
|---|---|---|---|
| Whole Blood (unprocessed) | Ambient | NA | |
| Plasma/Serum (processed) | Refrigerated (preferred) | 2 weeks | |
| Ambient | 2 days | ||
| Frozen | 4 month | ||
| Note: specimen should not be repeatedly frozen and thawed | |||
LOINC
4086-5
Last Reviewed
06/2025
Test Classification and CPT Coding
80164