CPT® Code 86618

The CPT® Code 86618 refers to a laboratory test specifically designed to measure antibodies against Borrelia burgdorferi, the bacterium responsible for Lyme disease. This test is crucial for diagnosing Lyme disease, particularly in patients exhibiting symptoms consistent with the infection. The test can be performed on serum, which is the liquid portion of blood, or cerebrospinal fluid (CSF), which surrounds the brain and spinal cord. It serves as a first-line screening tool for individuals who either live in or have traveled to areas where black-legged ticks, the vectors for Lyme disease, are prevalent. The accuracy of this test is notably higher when conducted within four weeks following a tick bite, especially if the patient presents with erythema migrans, commonly known as the "bull's eye" rash, which is a hallmark sign of Lyme disease. The presence of C6 peptide antibodies to B. burgdorferi is particularly significant, as it is recognized as a standalone diagnostic marker for Lyme disease. In the early stages of infection, IgM antibodies typically become detectable within 2 to 3 weeks post-exposure, aiding in the diagnosis of early Lyme disease. Conversely, IgG antibodies, which also indicate exposure, do not reach their peak levels until approximately 4 to 6 months after the initial infection. In cases where the C6 peptide antibodies test positive or yield equivocal results, further testing for IgG and IgM antibodies is recommended. Additionally, positive or uncertain results for these antibodies should prompt a reflex to a Western Blot or immunoblot confirmation test to ensure accurate diagnosis. The collection of blood samples for this test is performed through a separately reportable venipuncture, while CSF samples are obtained via a separately reportable lumbar puncture. The testing of both serum and CSF is conducted using a semi-quantitative enzyme-linked immunosorbent assay (ELISA), a widely used laboratory technique for detecting and quantifying proteins, including antibodies.