title: [Missed hyperinsulinaemia in a patient with an insulinoma].
abstract: In a 57-year-old man with symptomatic hypoglycaemias which gave cause to suspect an insulinoma, normal insulin levels were initially found. A repeated fasting assay at another hospital did, however, reveal the expected hyperinsulinaemia. Scans revealed an abnormality in the pancreas. After surgical removal of the insulin-producing tumour the patient made a quick recovery. The diagnosis of organic hyperinsulinaemia is established by demonstrating inappropriately high serum-insulin concentrations during fasting hypoglycaemia. The diagnostic normative values are based on the classic polyclonal method of determination. This new highly-specific insulin assay has no cross-reactivity with pro-insulin, which is often produced disproportionately more by an insulinoma. As a result of this false-normal insulin values are found. Therefore new normative values are needed for the newer insulin assays when diagnosing an insulin-producing islet cell tumour. Pro-insulin and C-peptide assays may play a useful role in this.
authors.affiliation: Afd. Interne Geneeskunde, Scheper Ziekenhuis, Boermarkeweg 60, 7824 AA Emmen. r.wouters@sze.nl
authors.forename: R S M E
authors.initials: RS
authors.lastname: Wouters
authors.forename: J M W
authors.initials: JM
authors.lastname: van den Ouweland
authors.forename: J G J
authors.initials: JG
authors.lastname: Pouwels
authors.forename: B H R
authors.initials: BH
authors.lastname: Wolffenbuttel
mesh_terms: D001786:Blood Glucose / Q000378:metabolism; D003429:Cross Reactions; D005215:Fasting; D006801:Humans; D006946:Hyperinsulinism / Q000209:etiology*; D007003:Hypoglycemia / Q000209:etiology*; D007328:Insulin / Q000097:blood*; D007340:Insulinoma / Q000097:blood / Q000150:complications / Q000175:diagnosis* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D010180:Pancreatectomy; D010190:Pancreatic Neoplasms / Q000097:blood / Q000150:complications / Q000175:diagnosis* / Q000601:surgery; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
chemical_list: D001786:Blood Glucose; D007328:Insulin