Neurone Specific Enolase ( NSE ) Gamma-Enolase

Immunology

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Description

The main application of all tumour markers is monitoring for relapse or progression. Use as a diagnostic aid requires care and knowledge of the test limitations. Opportunistic screening is discouraged. Enolase is a glycolytic enzyme which catalyses the conversion of 2-phosphoglycerate to phosphoenolpyruvate. Brain and neuroendocrine tissues contain two forms of enolases, denoted alpha and gamma enolase to indicate that they are dimers of biochemically and immunologically distinct subunits ( alpha-alpha and gamma-gamma ). A hybrid form ( alpha-gamma ), with intermediate biochemical and immunological properties, is also present in these tissues. In brain, the alpha-enolase is confined to glial cells, while the gamma form is found in neurons and therefore has been termed neuron-specific enolase ( NSE ). NSE is further found in the amino precursor uptake and decarboxylation ( APUD ) cells. Besides the alpha-enolase, which is found in most cells, and NSE, a third form of enolase ( beta-beta ) is present in muscle cells. In several types of neoplasia there is a shift in isoenzyme pattern to the gamma isoform [1,3]. Elevated levels of NSE have been described in most tumours of neuroectodermal or neuroendocrine origin including neuroblastoma, small-cell carcinoma of the lung, melanoma, pancreatic islet-cell carcinoma and hypernephroma [3]. The elevated levels associated with small-cell lung carcinoma, pancreatic islet-cell carcinoma and APUD tumours are of value in monitoring tumour bulk but are of little value as a primary diagnostic aid. NSE concentration has been found to change in accordance with disease status [2]. Serum NSE can be of diagnostic value in suspected cases of neuroblastoma in childhood and, in this situation, provides a satisfactory monitor of tumour bulk after initial treatment [4]. Increased levels may also be seen in patients using PPIs and in renal insufficiency.

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Indications

Monitoring and diagnosis of neuroendocrine tumours. NSE has been found in tumours of neuroblastoma and small-cell carcinomas of the lung, APUD and melanoma.

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Sample Type

2mL Serum ( Gel 5mL Yellow tube ). Requests from outside Sheffield: Transport at ambient temperature via Royal Mail or Courier.

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Reference Range

Normal value: <12.5 g/L.Reference range established by manufacturer and verified in house.

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Turnaround Time

Within 3 days

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Testing Frequency

Daily

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External Notes

Tumour Markers are not diagnostic and are of most use in monitoring response to treatment and early detection of relapse. Normal values do NOT exclude malignancy. Quoted ranges only valid for serum.

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References

PRU Handbook of Clinical Immunochemistry. 9th Edition. 2007. [Ref 1]
Ferringo D, Bucherri G and Giordano C. Neuron specific enolase is an effective tumour marker in non-small cell lung carcinoma ( NSCLC ). Lung Can. 2003. 41:311-320. [Ref 2]
Adewolf IF and Newlands ES. Neuron-specific enolase ( NSE ) as a tumour marker and comparative evaluation with carcinoembryonic antigen ( CEA ) in small cell lung cancer. Med Onc Tum Pharm. 1987. 4( 1 ):11-15. [Ref 3]
Zelter PM, et al. Serum neuron-specific enolase in children with neuroblastoma. Relationship to stage and disease course. Cancer. 1986. 57( 6 ):1230-1234. [Ref 4]

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