CPT® Code 80164

The CPT® Code 80164 refers to a laboratory test specifically designed to measure the total concentration of valproic acid, also known as dipropylacetic acid or depakote. Valproic acid is classified as an anticonvulsant medication, which is commonly utilized in the management of various medical conditions, including seizure disorders, the manic phase of bipolar disorder, and migraine headaches. The mechanism of action for valproic acid involves altering the levels of certain neurotransmitters in the brain, which helps to stabilize mood and prevent seizures. The total valproic acid test is crucial for monitoring the effectiveness of drug therapy, ensuring patient compliance with prescribed treatment regimens, and evaluating the potential for drug toxicity. In cases where the total valproic acid concentration falls within the normal range, a separate test for free valproic acid (CPT® Code 80165) may be conducted to investigate the underlying causes of toxicity, particularly in patients who exhibit altered or unpredictable protein binding capacities. The testing process involves obtaining a blood sample through venipuncture, which is performed just prior to the administration of medication to capture the trough level of the drug. The laboratory analysis for total valproic acid is conducted using fluorescence polarization immunoassay techniques, while the assessment for free valproic acid employs quantitative enzyme multiplied immunoassay methods.