Useful in the differentiated diagnosis of Creutzfeldt-Jakob disease for other dementing disease.
Limitations
All 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. Not a screening test.
Hemolysis can lead to significant artifactual NSE elevations, because erythrocytes contain NSE.
Proton pump inhibitor treatment, hemolytic anemia, hepatic failure, and end-stage renal failure can also result in artifactual NSE elevations.
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 neurologic diagnosis, NSE-secreting tumors can represent a source of false-positive results.
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 rebaselined.
NEUTROPHIL TESTS FOR DYSFUNCTION
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Definition
Inherited or acquired disorders affecting neutrophils (and other leukocytes) may result in abnormal function and a predisposition to recurrent bacterial infections. Acquired neutrophil dysfunction may be the result of disorders of immunoglobulins, complement, or T cells; in such cases, the underlying disease should be characterized before specific assays for neutrophil dysfunction are undertaken.
Use
Neutrophil function tests are used to evaluate neutrophil dysfunction in patients with recurrent bacterial infections, especially in patients with a family history suggestive of a neutrophil dysfunction syndrome. The functions used to investigate neutrophil dysfunction are adherence, locomotion, phagocytosis, and secretion (see Table 16.58). Morphologic studies are performed in parallel with the functional assays. Because of the rarity of these conditions, only a limited number are mentioned (see Table 16.58).
TABLE 16–58. Assays for Suspected Congenital Neutrophil Dysfunction Syndromes
