title: Comparison of two low-dose calcium infusion schedules for localization of insulinomas by selective pancreatic arterial injection with hepatic venous sampling for insulin.
abstract: OBJECTIVE
  Localization of small insulinomas may be difficult. Selective pancreatic arterial injection of calcium with hepatic venous insulin measurement (SACST) has been used for this purpose, but can rarely cause hypoglycaemia. Two low-dose concentrations of calcium, 0·25 and 0·1 of the usual concentration used for the test, have been compared for sensitivity of localization and safety.
  
  
  METHODS
  Selective pancreatic arterial injection of calcium with hepatic venous insulin measurement was performed at calcium concentrations of 0·0025 (Protocol A) and 0·00625 (Protocol B) mEq calcium per kg. The standard concentration is 0·025 mEq/kg.
  
  
  METHODS
  Twenty one successive patients with biochemical evidence of insulinoma were studied.
  
  
  RESULTS
  Using surgical localization as the gold standard, Protocol A had a sensitivity of 91% and Protocol B 75% for correct localization. The false-positive localization rate was 16%. No hypoglycaemia was observed. These results compare favourably with published data using the standard calcium concentration. Selective pancreatic arterial injection of calcium with hepatic venous insulin measurement was superior to localization by noninvasive imaging; in seven cases, SACST was correct when conventional imaging was negative (five) or false positive (two).
  
  
  CONCLUSIONS
  Low concentrations of calcium are effective and safe when performing SACST for localization of insulinoma.
authors.affiliation: Department of Endocrinology, Greenlane Clinical Centre and Auckland City Hospital, Auckland, New Zealand.
authors.forename: G
authors.initials: G
authors.lastname: Braatvedt
authors.forename: E
authors.initials: E
authors.lastname: Jennison
authors.forename: I M
authors.initials: IM
authors.lastname: Holdaway
mesh_terms: D000328:Adult; D000368:Aged; D002118:Calcium / Q000008:administration & dosage*; D004334:Drug Administration Schedule; D005260:Female; D006503:Hepatic Veins / Q000378:metabolism*; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D007340:Insulinoma / Q000175:diagnosis* / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010179:Pancreas / Q000378:metabolism*
chemical_list: D007328:Insulin; D002118:Calcium