Valproic Acid, Free, Serum
Use
Monitoring free valproic acid is crucial in therapy to ensure therapeutic drug levels are maintained while minimizing the potential for toxicity. In conditions such as uremia, or when co-administered with other highly protein-bound drugs, free valproic acid levels provide a more accurate reflection of the active drug concentration in the bloodstream. This is particularly important in cases of hypoalbuminemia, pregnancy, renal or hepatic impairment, and in geriatric patients, where total valproic acid measurements might underrepresent the free active fraction.
Special Instructions
For accurate results, serum gel tubes must be centrifuged within two hours of collection. If using red-top tubes, the serum should be aliquoted into a plastic vial within the same timeframe. If not ordering electronically, complete and send a Therapeutics Test Request form with the specimen.
Limitations
Valproic acid's free fraction is influenced by alterations in serum proteins, hence inaccurate results might occur if specimens are exposed to significant heat or other conditions leading to protein denaturation. Assaying both free and total valproic acid may give a comprehensive view, but timing of collection post-dose influences interpretations of clinical significance due to fluctuations in drug concentration.
New York Approved
Methodology
Immunoassay (Multiplex Protein Panel)
Biomarkers
LOINC Codes
- 4087-3
- 4087-3
Result Turnaround Time
0-1 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
2 mL
Minimum Volume
1 mL
Container
Plastic vial
Collection Instructions
Serum gel tubes should be centrifuged within 2 hours of collection. Red-top tubes should be centrifuged, and the serum aliquoted into a plastic vial within 2 hours of collection.
Causes for Rejection
Gross hemolysis
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 72 hours |
| Refrigerated | 14 days |
| Frozen | 28 days |