Home
HelpEpic Test Code LAB683 Ethosuximide, Serum
Additional Codes
MML:ETX
Specimen Required
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 0.5 mL
Collection Instructions:
1. Serum gel tubes should be centrifuged within 2 hours of collection.
2. Red-top tubes should be centrifuged and the serum aliquoted into a plastic vial within 2 hours of collection.
Useful For
Monitoring ethosuximide therapy
Determining compliance
Assessing ethosuximide toxicity
Method Name
Enzyme-Multiplied Immunoassay Technique (EMIT)
Reporting Name
Ethosuximide, SSpecimen Type
SerumSpecimen Minimum Volume
0.25 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 14 days | |
| Frozen | 28 days | ||
| Ambient | 14 days |
Reject Due To
| Gross hemolysis | Reject |
Clinical Information
Ethosuximide (Zarontin) is used in the treatment of absence (petit mal) epilepsy in adults and children 3 years and older. Ethosuximide is almost completely absorbed from the gastrointestinal tract, reaching a peak plasma concentration in 1 to 4 hours following oral administration.
Approximately 10% to 20% of the drug is excreted unchanged in the urine; the remainder is metabolized by hepatic microsomal enzymes. The volume of distribution of ethosuximide is approximately 0.7 L/kg, and its half-life is 17 to 56 hours (adult) and 30 hours (pediatric). Minimal ethosuximide circulating in the blood is bound to protein (approximately 22%).
Ethosuximide produces a barbiturate-like toxicity, characterized by central nervous system and respiratory depression, nausea, and vomiting, when the blood level is greater than 120 mcg/mL.
Reference Values
Therapeutic: 40-100 mcg/mL
Critical value: >150 mcg/mL
Interpretation
Dosage is guided by blood levels; the therapeutic range for ethosuximide is 40 to 100 mcg/mL.
Toxic concentration: above 120 mcg/mL.
Cautions
No significant cautionary statements
Day(s) Performed
Monday through Saturday
Report Available
Same day/1 daySpecimen Retention Time
2 weeksPerforming Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
80168
NY State Approved
YesForms
If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:
-Therapeutics Test Request (T831)