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Comparison of the Automated KRYPTOR Chromogranin A Assay with the DAKO ELISA by Magnus Wolf, Isolde Riedlinger, Rainer Lehmann, Hans-Ulrich Haering, Erwin Schleicher, Andreas Peter

Background: Currently available assays for the widely used marker for neuroendocrine tumors chromogranin A have a weak comparability, involve manual work, and require batch processing of the samples. In this study, we evaluated the automated chromogranin A KRYPTOR assay compared with the widely used DAKO ELISA.
Methods: 83 samples were measured with the DAKO ELISA (EDTA plasma) and the KRYPTOR assay (serum), since different sample materials are recommended. Furthermore, different sample materials were compared.
Results: The results between the two assays were highly correlated (KRYPTOR serum (ng/mL) = 2.887 ELISA EDTA (U/L) + 5.028; r = 0.99). The inter-assay variation for the KRYPTOR assay was determined as 5.56% at low (95 ng/mL; n = 34) and 6.21% at high (530 ng/mL; n = 33) chromogranin A concentrations. EDTA plasma samples revealed significantly lower results than serum in the KRYPTOR assays and could not be used.
Conclusions: In conclusion, the new chromogranin A KRYPTOR assay is fast, reliable, and compares well to an established test after adaptation of sample material and reported units.

DOI: 10.7754/Clin.Lab.2014.140422