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Immunology & Autoimmune
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Currently under review
Pending specialist review and validation.
This blood test measures the concentration of oxcarbazepine’s active metabolite, often called 10-hydroxycarbazepine (MHD), in your bloodstream. It is a therapeutic drug monitoring test that helps your care team understand how much medicine is in your system at a steady state.
The sample is usually drawn as a trough, just before your next dose, to provide a consistent picture of exposure.
Keeping the drug level in a suitable range can help balance seizure control with side effects. A level that is too low may be associated with breakthrough seizures, missed doses, absorption problems, or faster drug clearance.
A level that is too high may increase the chance of dizziness, sleepiness, double vision, or other adverse effects. Your clinician may order this test when starting or adjusting treatment, if seizures or side effects change, when adding or stopping interacting medicines, during pregnancy, or if kidney function changes.
Your result is interpreted together with your symptoms, seizure control, side effects, dose, formulation, and the timing of the blood draw. One number on its own rarely tells the whole story, and individualized targets may differ based on your situation.
If a result is unexpected, your clinician may confirm the sample timing, review other medicines and supplements, consider kidney function and sodium levels, and repeat the test if needed. Do not change your dose unless your clinician advises you to do so.
Reference intervals vary by laboratory, analyzer, methodology, population, and units. The ranges shown here are for education only. Always interpret your results against the reference interval printed on your own lab report.
For consistent interpretation, the blood draw is ideally a trough taken just before your next dose. Samples taken at other times can read higher or lower and may not reflect steady-state exposure.
Medicines that affect liver enzymes can change oxcarbazepine levels. Enzyme inducers like carbamazepine, phenytoin, or phenobarbital may lower levels, while certain inhibitors and some antibiotics or antifungals may increase them.
The active metabolite is cleared by the kidneys. Reduced kidney function can lead to higher levels, while improved function or increased elimination can lower levels, which may require dose adjustments.
During pregnancy and in children, drug handling can change due to altered metabolism and volume of distribution. Levels may drift over time and require closer monitoring and dose review.
Immediate-release versus extended-release tablets can yield different peak and trough patterns. Missed doses or variable intake times often produce lower or fluctuating results.
Vomiting, diarrhea, or malabsorption can reduce how much drug is absorbed, leading to lower measured levels despite taking the prescribed dose.
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