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Test Code VALPX Valproic Acid, Plasma or Serum

Performing Laboratory

Bronson Laboratory Services-Chemistry

Specimen Required

Please call Bronson Laboratory Services at 269-341-6440 with questions regarding draw times. 

Container Type:


Inpatient: Mint

STAT: Mint

Outpatient: Gold 

Acceptable: Red Top or Green Lithium Heparin.


Optimal Collection Volume: 

4.5 mL; Full Tube

Collection Instructions:

1. Draw blood just prior to next dose. If not possible, there must be a minimum of 2 hours since the last dose.

2. Indicate time of last dose on request form.

3. Gently invert sample 5-6 times after collection.

Processing Instructions: 

1. Allow serum sample to clot for 30 minutes.

2. Centrifuge specimen within 2 hours of collection.

3. Specimen tubes without a gel barrier should have the serum or plasma aliquoted to a false bottom container after centrifugation.

4. Keep serum/plasma refrigerated until testing can be performed.

Reference Values

50-100 mcg/mL

Critical value (automatic call-back): ≥200 mcg/mL



Specimen Transport Temperature


Specimen Stability

Collect serum using standard sampling tubes. SST/gel separation tubes may be used, however sample must be  separated within 24 hours of collection; therefore if collected in a gel tube, transfer to a non-gel tube after centrifugation.  Serum Stability: 1 week capped at 2-8°C 4 weeks at -20°C.

Plasma from sodium or lithium heparin or sodium EDTA  may also be used, however the separated sample is only stable for 2 days referigerated.


Day(s) Test Set Up

Monday through Sunday

Test Classification and CPT Coding