Methsuximide and Normethsuximide, Serum or Plasma
Ordering Recommendation

Optimize drug therapy and monitor patient adherence.

Quantitative Gas Chromatography/Mass Spectrometry
Mon, Thu
1-5 days
New York DOH Approval Status
This test is New York DOH approved.
Submit With Order
ARUP Consult®
Disease Topics
Specimen Required
Patient Preparation
Plain Red, Lavender (K2EDTA), Lavender (K3EDTA), or Pink (K2EDTA) 
Specimen Preparation
Separate from cells ASAP or within 2 hours of collection. Transfer 1 mL serum or plasma to an ARUP Standard Transport Tube. (Min: 0.5 mL) 
Storage/Transport Temperature
Unacceptable Conditions
Whole blood. Gel Separator Tubes, Light Blue (Sodium Citrate), or Yellow (SPS or ACD Solution). 
Please indicate in the supplied fields:
1.  Dose - List drug amount and include the units of measure
2.  Route - List the route of administration (IV, oral, etc.)
3.  Dose Frequency - Indicate how often the dose is administered (per day, per week, as needed, etc.)
4.  Type of Draw - Indicate the type of blood draw (Peak, Trough, Random, etc.) 
Ambient: 5 days; Refrigerated: 2 weeks; Frozen: 1 month 
Reference Interval
Therapeutic RangeTotal (methsuximide and normethsuximide): 10-40 µg/mL
Therapeutic RangeMethsuximide: < 1 µg/mL
Therapeutic RangeNormethsuximide: 10-40 µg/mL
Toxic LevelTotal (methsuximide and normethsuximide): > 60 µg/mL

Interpretive Data
The therapeutic range is based on serum pre-dose (trough) draw at steady-state concentration. Adverse effects may include nausea, drowsiness, ataxia, blurred vision and blood dyscrasias.

CPT Code(s)
Component Test Code*Component Chart NameLOINC
2011532Meth and Normet, Ser/Pla10543-7
2011533Methsuximide (Celontin), Ser/Pla3801-8
2011534Methsux/Normethsux Dose4326-5
2011535Methsux/Normethsux Dose Frequency52810-9
2011536Methsux/Normethsux Route45373-8
2011537Methsux/Normethsux Type of Draw49049-0
2011538Normethsuximide, Ser/Pla10546-0
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
  • Celontin
  • Celontin blood level
  • Desmethylmethsuximide
  • Methsuximide and Metabolite
  • Normethsuximide