Cautions

All neuron-specific enolase (NSE) test results must be considered in the clinical context, and interferences or artifactual elevations should be suspected if the clinical NSE test results are at odds with the clinical picture or other tests.

Hemolysis can lead to significant artifactual NSE elevations since erythrocytes contain NSE.

Hemoglobin concentrations as low as 20 mg/dL were found to have an adverse effect on NSE testing.

Proton pump inhibitor treatment, hemolytic anemia, hepatic failure, and kidney failure can also result in artifactual NSE elevations.

Other false-positive results depend on the treating context. When performing NSE testing for tumor diagnosis or follow-up, epileptic seizure, brain injury, encephalitis, stroke, and rapidly progressive dementia might result in false-positive results. On the other hand, when NSE testing is performed to assist in neurological diagnosis, NSE-secreting tumors can represent a source of false-positive results.

Neuron-specific enolase values can vary significantly between methods/assays. Serial follow-up should be performed with the same assay. If assays are changed, patients should have their baseline level reestablished.

This assay is an immunometric assay and can, in rare situations, be affected by false-low results in the presence of extremely high NSE concentrations ("hooking") or autoantibodies to NSE.

In rare cases, some individuals can develop antibodies to mouse or other animal antibodies (often referred to as human anti-mouse antibodies [HAMA] or heterophile antibodies), which may cause interference in some immunoassays. Caution should be used in interpretation of results, and the laboratory should be alerted if the result does not correlate with the clinical presentation.