Analytical aspects of gastrin measurement in neuroendocrine tumors

Rationale:Biochemical diagnostics of neuroendocrine tumors (NETs) is based on the analysis of universal and specific markers, according to the tumor type and clinical manifestations of the disease. Measurement of gastrin levels in the serum of NETs patients is important in the diagnosis of the functioning pancreatic, gastric and duodenal NETs.Aim:To perform a comparative analysis of the results of gastrin measurement as a biochemical marker of NETs using different test-systems.Materials and methods: Serum gastrin was measured in the serum of 30 NET patients and 18 normal controls by immunochemiluminescent (Immulite 2000 Gastrin, “Siemens”) and ELISA (Gastrin-17 ELISA, “Biohit”) assays.Results:The analysis of the results of gastrin measurement by immunochemiluminescent and ELISA methods showed significant variability of its levels, reaching 2016 and 1988 pmol/l, respectively. Comparable analytical sensitivity of the two test systems was confirmed by similar increases (over 30- to 40-fold) of the median levels of the hormone in the serum of patients with gastric NETs, compared to healthy controls. The analysis of diagnostic efficacy accounting for their respective cut-offs demonstrated higher sensitivity (95.4%) of the Immulite 2000 Gastrin test-system, which measures total gastrin, than that of the ELISA method (80.0%), specific to gastrin-17.Conclusion:The analysis shows high efficacy of immonochemiluminescent method of measurement of total gastrin as a biochemical marker of NETs.