Used to evaluate for insulin producing neoplasms (islet cell tumor, insulinoma), or pancreatic islet cell hyperplasia to work up hypoglycemia to evaluate insulin production in diabetes mellitus. It is unable to distinguish endogenous insulin in patients receiving exogenous insulin.
Collect specimen in a red top or SST tube from a fasting patient. Centrifuge, aliquot serum into plastic vial and refrigerate. Grossly hemolyzed specimens are unacceptable. Fasting specimen, normal volume 1.5 mL serum (minimum 1 mL).