CPT code 0443U is a Proprietary Laboratory Analyses (PLA) code for the Neurofilament Light Chain (NfL) test performed by the Neuromuscular Clinical Laboratory at Washington University in St. Louis School of Medicine; the test uses an ultrasensitive immunoassay on serum or cerebrospinal fluid specimens to detect NfL, a biomarker of nerve cell injury, and is classified as a laboratory pathology test typically performed in a clinical laboratory or hospital laboratory setting.

For related coverage guidance, see recent payer policy updates: RTM Testing of Homocysteine Metabolism-Related Conditions, Multimarker Serum Testing Related to Ovarian Cancer, Genomic Profiling for Selecting Targeted Cancer Therapies.