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The CPT® Code 80186 refers to the measurement of free phenytoin levels in the blood. Phenytoin, commonly known by its brand names such as Dilantin, Phenytek, or Phenytoin Prompt, is an anticonvulsant medication primarily used to manage and treat seizures. It functions by reducing electrical activity in the brain, which is crucial for preventing seizure episodes. The administration of phenytoin can occur either orally or through injection, depending on the clinical scenario and patient needs. Due to its narrow therapeutic range, it is essential to monitor both total and free phenytoin levels in patients receiving this medication. Total phenytoin levels indicate the overall serum concentration of the drug, while free phenytoin levels represent the unbound, biologically active portion of the drug. It is important to note that only the free phenytoin is pharmacologically active, as approximately 90% of phenytoin in the bloodstream is bound to proteins and thus inactive. This binding can be influenced by other medications that may displace phenytoin from its protein binding sites, potentially leading to elevated free phenytoin levels. Regular monitoring of blood concentration levels is critical, particularly during routine follow-ups and in instances of breakthrough seizures, which may suggest that the therapeutic levels of phenytoin are insufficient. The process of obtaining a blood sample for this test involves a venipuncture, which is reported separately, followed by the analysis of the serum using immunoassay techniques to determine the free phenytoin concentration.
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The measurement of free phenytoin levels is indicated in the following scenarios:
The procedure for measuring free phenytoin levels involves several key steps:
After the blood sample has been collected and processed, the patient may resume normal activities unless otherwise directed by their healthcare provider. It is important for the healthcare team to review the results of the free phenytoin level test in conjunction with the patient's clinical status and medication regimen. If the levels are found to be outside the therapeutic range, adjustments to the phenytoin dosage may be necessary, and the patient should be monitored closely for any signs of toxicity or inadequate seizure control. Follow-up testing may be scheduled to ensure that the adjustments made are effective in achieving the desired therapeutic outcomes.
| Short Descr | ASSAY OF PHENYTOIN FREE | Medium Descr | DRUG SCREEN QUANTITATIVE PHENYTOIN FREE | Long Descr | Phenytoin; 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. | Q4 | Service for ordering/referring physician qualifies as a service exemption | 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. | 59 | Distinct procedural service: under certain circumstances, it may be necessary to indicate that a procedure or service was distinct or independent from other non-e/m services performed on the same day. modifier 59 is used to identify procedures/services, other than e/m services, that are not normally reported together, but are appropriate under the circumstances. documentation must support a different session, different procedure or surgery, different site or organ system, separate incision/excision, separate lesion, or separate injury (or area of injury in extensive injuries) not ordinarily encountered or performed on the same day by the same individual. however, when another already established modifier is appropriate it should be used rather than modifier 59. only if no more descriptive modifier is available, and the use of modifier 59 best explains the circumstances, should modifier 59 be used. note: modifier 59 should not be appended to an e/m service. to report a separate and distinct e/m service with a non-e/m service performed on the same date, see modifier 25. | 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. | GA | Waiver of liability statement issued as required by payer policy, individual case | GV | Attending physician not employed or paid under arrangement by the patient's hospice provider | 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. |
| 1993-01-01 | Added | First appearance in code book in 1993. |
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