CPT® Code 80156

The CPT® Code 80156 refers to a laboratory test that measures the total level of carbamazepine in the blood. Carbamazepine, commonly known by its brand name Tegretol, is an anticonvulsant medication primarily used to manage epilepsy. Additionally, it serves as an analgesic for conditions such as trigeminal neuralgia. The measurement of total carbamazepine levels is crucial for determining the appropriate dosage for patients undergoing treatment for epilepsy and for monitoring potential toxicity associated with the drug. The test evaluates both the total amount of carbamazepine present in the bloodstream and its relationship with protein binding. Typically, about 75% of circulating carbamazepine is bound to proteins in the blood. However, in certain patients, carbamazepine can be displaced from these proteins, leading to elevated levels of free carbamazepine. This situation necessitates careful monitoring, as lower total levels may still result in toxicity due to increased free drug levels. The test is performed by obtaining a blood sample through venipuncture, and the serum is analyzed using various techniques, such as high-performance liquid chromatography or fluorescent polarization immunoassay, to ensure accurate measurement of the total carbamazepine concentration.