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The CPT® Code 80157 refers to a laboratory test specifically designed to measure the levels of free carbamazepine in the blood. Carbamazepine, commonly known by its brand name Tegretol, is an anticonvulsant medication primarily used in the management of epilepsy. Additionally, it serves as an analgesic for conditions such as trigeminal neuralgia. The measurement of free carbamazepine is crucial for determining the appropriate dosage for patients with epilepsy and for monitoring potential toxicity associated with the drug. This test is particularly important because carbamazepine is typically 75% bound to proteins in the bloodstream, meaning that only a fraction of the drug is active and available to exert its therapeutic effects. In certain patients, factors may lead to the displacement of carbamazepine from these proteins, resulting in elevated levels of free carbamazepine. Monitoring these unbound levels is essential, as they can indicate a risk of toxicity if the total drug levels are not adequately managed. The test is performed on a blood sample obtained through venipuncture, and the analysis is conducted using advanced laboratory techniques such as high-performance liquid chromatography or fluorescent polarization immunoassay.
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The test for free carbamazepine levels is indicated for several specific clinical scenarios, particularly in the management of patients undergoing treatment with carbamazepine. The following conditions warrant the performance of this laboratory test:
The procedure for testing free carbamazepine levels involves several key steps that ensure accurate measurement and analysis. The following outlines the procedural steps:
After the procedure, patients may experience minimal discomfort at the venipuncture site, which typically resolves quickly. There are no specific post-procedure care instructions required for this test; however, patients should be advised to monitor the site for any unusual signs such as excessive bleeding or infection. The healthcare provider will review the test results with the patient, discussing any necessary adjustments to the carbamazepine dosage based on the free level findings and overall treatment plan. Regular monitoring may be recommended to ensure ongoing efficacy and safety of the treatment.
| Short Descr | ASSAY CARBAMAZEPINE FREE | Medium Descr | DRUG ASSAY CARBAMAZEPINE FREE | Long Descr | Carbamazepine; free | 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 | 2 | CCS Clinical Classification | 235 - Other Laboratory |
| 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. | 77 | Repeat procedure by another physician or other qualified health care professional: it may be necessary to indicate that a basic procedure or service was repeated by another physician or other qualified health care professional subsequent to the original procedure or service. this circumstance may be reported by adding modifier 77 to the repeated procedure or service. note: this modifier should not be appended to an e/m service. | 91 | Repeat clinical diagnostic laboratory test: in the course of treatment of the patient, it may be necessary to repeat the same laboratory test on the same day to obtain subsequent (multiple) test results. under these circumstances, the laboratory test performed can be identified by its usual procedure number and the addition of modifier 91. note: this modifier may not be used when tests are rerun to confirm initial results; due to testing problems with specimens or equipment; or for any other reason when a normal, one-time, reportable result is all that is required. this modifier may not be used when other code(s) describe a series of test results (eg, glucose tolerance tests, evocative/suppression testing). this modifier may only be used for laboratory test(s) performed more than once on the same day on the same patient. | GW | Service not related to the hospice patient's terminal condition |
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| 2013-01-01 | Changed | Medium description changed per AMA 2013 corrections document dated January 25, 2013. |
| 2011-01-01 | Changed | Short description changed. |
| 2001-01-01 | Added | First appearance in code book in 2001. |
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