Elevated NSE of 31ng/ml is not normal, NSE is a tumor marker, and its elevation is commonly found in small cell lung cancer, but there are also other factors that cause it to be elevated, and the specific reason for the elevation needs to be evaluated by the doctor in conjunction with the patient’s past history. The full name of NSE is neuron-specific enolase, which is found in neural and neuroendocrine tissues and is one of the enolases involved in the glycolysis pathway. Neuron-specific enolase is found in tumors associated with neuroendocrine tissue origins, particularly small cell lung cancer. Neuron-specific enolase, an isoenzyme of enolase, is highly positive in small-cell lung cancer and is commonly used to monitor the prognosis and progression of small-cell lung cancer. Elevated concentrations of neuron-specific enolase can also be seen in the serum of neuroblastoma, neuroendocrine cell tumor, pancreatic islet cell tumor and melanoma. Elevated neuron-specific enolase should be evaluated by a physician in conjunction with the patient’s medical history and ancillary tests.