Falsely Elevated Levels of Pancreastatin, a Neuroendocrine Tumor Marker

Chromogranin A and pancreastatin are neuroendocrine tumor markers. A 69-yearold female presented for diagnosis and management of a potential neuroendocrine tumor related to nausea, vomiting, and diarrhea for over 40 years. Initial neuroendocrine tumor work-up only revealed a slightly elevated chromogranin A level. Computed Tomography (CT) of chest, abdomen, and pelvis did not find neuroendocrine tumors. Her pancreastatin levels were higher than upper limit of normal at one commercial laboratory with a pancreastatin assay developed in-house but entirely normal in another which used a validated assay. The patient in this case illustrates an often-neglected cause of false positive test result, namely, spurious assay. Clinicians need to critically analyze a given test result in the context of clinical history, physical examination findings, other biochemical test and imaging results, and histological evidence, and to determine if an unexpected test result is false positive.