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Test Code ETHOSUX Ethosuximide, Serum

Useful For

Monitoring therapy

 

Determining compliance

 

Assessing toxicity

Method Name

Enzyme-Multiplied Immunoassay Technique (EMIT)

Reporting Name

Ethosuximide, S

Specimen Type

Serum


Specimen Required


Container/Tube:

Preferred: Serum gel

Acceptable: Red top

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 aliquoted within 2 hours of collection.


Seattle Children's Hospital Note:

Collect 1.0 mL whole blood in a red or gold top.

Specimen Minimum Volume

0.25 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Refrigerated (preferred) 14 days
  Frozen  28 days
  Ambient  14 days

Reject Due To

Hemolysis

Mild OK; Gross reject

Lipemia

NA

Icterus

NA

Other

NA

Reference Values

Therapeutic: 40-100 mcg/mL

Critical value: >150 mcg/mL

Method Description

The assay is a homogeneous enzyme immunoassay technique used for the analysis of specific compounds in biological fluids. The assay is based on competition between drug in the sample and drug labeled with the enzyme glucose-6-phosphate dehydrogenase (G6PDH) for antibody binding sites. Enzyme activity decreases upon binding to the antibody, so the drug concentration in the sample can be measured in terms of enzyme activity. Active enzyme converts oxidized nicotinamide adenine dinucleotide (NAD) to NADH (the reduced form of NAD), resulting in an absorbance change that is measured spectrophotometrically. Endogenous serum G6PDH does not interfere, because the coenzyme functions only with the bacterial (Leuconostoc mesenteroides) enzyme employed in the assay.(Package insert: Siemens Ethosuximide reagent, Siemens Healthcare Diagnostics Inc., Newark, DE)

Day(s) and Time(s) Performed

Monday through Sunday; Continuously

Performing Laboratory

Mayo Medical Laboratories in Rochester

Test Classification

This test has been cleared or approved by the U.S. Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information

80168

LOINC Code Information

Test ID Test Order Name Order LOINC Value
ETHSX Ethosuximide, S In Process

 

Result ID Test Result Name Result LOINC Value
ETHSX Ethosuximide, S In Process

Forms

If not ordering electronically, complete, print, and send a Neurology Specialty Testing Client Test Request (T732) with the specimen (http://www.mayomedicallaboratories.com/it-mmfiles/neurology-request-form.pdf)