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Official Description

Zonisamide

© Copyright 2026 American Medical Association. All rights reserved.

Common Language Description

The CPT® Code 80203 refers to a laboratory test specifically designed to measure the levels of zonisamide in the blood. Zonisamide is a medication classified as a sulfonamide anticonvulsant, primarily utilized as an adjunctive treatment for adults experiencing partial-onset seizures. This means that it is often prescribed in conjunction with other medications to enhance seizure control. In addition to its primary use, zonisamide may also be prescribed off-label for various conditions, including migraine headaches, neuropathic pain, and bipolar disorder, indicating its versatility in treating different neurological and psychiatric disorders. Furthermore, zonisamide is currently undergoing clinical trials for potential applications in treating Parkinson's disease, marketed under the trade name Tremode, and for obesity, under the trade name Empatic. To ensure therapeutic efficacy and safety, monitoring of zonisamide levels is crucial, which is typically conducted through pre-dose (trough) blood draws. The blood sample required for this test is obtained via venipuncture, a procedure that is separately reportable. The analysis of the serum and/or plasma is performed using a quantitative enzyme multiplied immunoassay technique, which allows for precise measurement of the drug concentration in the bloodstream.

© Copyright 2026 Coding Ahead. All rights reserved.

1. Indications

The blood test for zonisamide levels is indicated for the following conditions:

  • Partial-Onset Seizures - Zonisamide is primarily used as an adjunct treatment for adults with partial-onset seizures, necessitating regular monitoring of drug levels to ensure therapeutic effectiveness and avoid toxicity.
  • Off-Label Uses - The medication may also be prescribed for migraine headaches, neuropathic pain, and bipolar disorder, where monitoring may be beneficial to assess the drug's impact and adjust dosages accordingly.
  • Clinical Trials - Zonisamide is being investigated for its potential use in treating Parkinson's disease and obesity, which may require level monitoring during the trial phases to evaluate safety and efficacy.

2. Procedure

The procedure for measuring zonisamide levels involves several key steps that ensure accurate results. First, a healthcare professional will perform a venipuncture, which is the process of puncturing a vein to obtain a blood sample. This step is crucial as it allows for the collection of serum or plasma, which is necessary for the subsequent testing. Once the blood sample is collected, it is processed to separate the serum or plasma from the cellular components. The next step involves utilizing a quantitative enzyme multiplied immunoassay technique, a sophisticated laboratory method that quantitatively measures the concentration of zonisamide in the blood. This technique is designed to provide precise and reliable results, which are essential for monitoring the drug levels in patients. The results of this test will inform healthcare providers about the appropriate dosing and management of zonisamide therapy, ensuring that patients receive optimal treatment.

3. Post-Procedure

After the blood sample has been collected for zonisamide level testing, there are generally no specific post-procedure care requirements for the patient. However, it is important for patients to follow any additional instructions provided by their healthcare provider regarding their medication regimen. Patients may be advised to wait for the test results before making any changes to their zonisamide dosage. Regular monitoring of zonisamide levels is essential, especially for those on long-term therapy, to ensure that the drug remains within the therapeutic range and to minimize the risk of adverse effects. If the test results indicate that the zonisamide levels are outside the expected range, healthcare providers may need to adjust the dosage or consider alternative treatment options.

Short Descr DRUG SCREEN QUANT ZONISAMIDE
Medium Descr DRUG SCREEN QUANTITATIVE ZONISAMIDE
Long Descr Zonisamide
Status Code Statutory Exclusion (from MPFS, may be paid under other methodologies)
Global Days XXX - Global Concept Does Not Apply
PC/TC Indicator (26, TC) 9 - Not Applicable
Multiple Procedures (51) 9 - Concept does not apply.
Bilateral Surgery (50) 9 - Concept does not apply.
Physician Supervisions 09 - Concept does not apply.
Assistant Surgeon (80, 82) 9 - Concept does not apply.
Co-Surgeons (62) 9 - Concept does not apply.
Team Surgery (66) 9 - Concept does not apply.
Diagnostic Imaging Family 99 - Concept Does Not Apply
CLIA Waived (QW) No
APC Status Indicator Conditionally packaged laboratory tests
Type of Service (TOS) 5 - Diagnostic Laboratory
Berenson-Eggers TOS (BETOS) T1H - Lab tests - other (non-Medicare fee schedule)
MUE 1
90 Reference (outside) laboratory: when laboratory procedures are performed by a party other than the treating or reporting physician or other qualified health care professional, the procedure may be identified by adding modifier 90 to the usual procedure number.
26 Professional component: certain procedures are a combination of a physician or other qualified health care professional component and a technical component. when the physician or other qualified health care professional component is reported separately, the service may be identified by adding modifier 26 to the usual procedure number.
GA Waiver of liability statement issued as required by payer policy, individual case
GW Service not related to the hospice patient's terminal condition
Q4 Service for ordering/referring physician qualifies as a service exemption
Date
Action
Notes
2014-01-01 Added Added
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