Cautions

All neuron-specific enolase (NSE) test results must be considered in the clinical context, and interferences or artefactual elevations should be suspected if the clinical NSE test results are at odds with the clinical picture of other tests. The laboratory should be contacted for assistance in these situations.

Hemolysis can lead to significant artefactual NSE elevations, since erythrocytes contain NSE. Hemoglobin concentrations as low as 20 mg/dL were shown to cause invalid NSE concentrations.

Proton pump inhibitor treatment, hemolytic anemia, hepatic failure, and end-stage renal failure can also result in artefactual NSE elevations.

Other false positives depend on the testing context. When performing NSE testing for tumor diagnosis or follow-up, recent epileptic seizures, brain injury, encephalitis, stroke, and rapidly progressive dementia might result in false-positive results.

When NSE testing is performed to assist in the diagnosis of CJD, recent epileptic seizures, brain injury, encephalitis, stroke, and NSE-secreting tumors can cause false-positive NSE elevations in cerebrospinal fluid (CSF).

There is insufficient evidence to support CSF NSE measurements in the prognostic evaluation of coma patients. Serum NSE should be used for this application, in conjunction with clinical predictors (pupillary light responses, corneal reflexes, motor responses to pain, myoclonus, status epilepticus), electroencephalogram, sensory-evoked potentials, and imaging.

NSE values can vary significantly between methods/assays. Serial follow-up should be performed with the same assay. If assays are changed, patients should be re-baselined.

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