Role of endoscopic ultrasonography in the localization of insulinomas and gastrinomas.

BACKGROUND: We have previously found selective venous sampling to be the most sensitive method to localize otherwise occult functioning endocrine tumors. However, recently we have used endoscopic ultrasonography (EUS) as the initial and in some cases the only localization study in the preoperative evaluation of proven insulinomas and of selected cases of gastrinoma. METHODS: All patients referred between April 1993 and April 1994 with a subsequently confirmed diagnosis of organic hyperinsulinism or Zollinger-Ellison syndrome (ZES) underwent EUS. Ten patients with insulinomas and six with gastrinomas were studied. Only one patient with ZES had multiple endocrine neoplasia type I. Patients with negative EUS findings had additional localization procedures including angiography and arterial stimulation tests. All but one patient underwent surgical exploration. RESULTS: Solitary insulinomas were found in all 10 patients. EUS correctly identified and localized the insulinoma in seven (70%) of 10 patients but failed to identify two pedunculated insulinomas that were easily found at exploration. Because of an incomplete examination, a single insulinoma was not detected within the parenchyma. The EUS examination correctly excluded the pancreatic gastrinomas in five patients. The sixth patient, who had multiple endocrine neoplasia type I, had two 0.5 cm tumors in the head. CONCLUSIONS: EUS is a sensitive and cost-effective technique for localization of insulinomas and may be the only study needed. In patients with ZES a negative pancreatic result suggests the likelihood of a duodenal or other extrapancreatic tumor.

Protective effects of enalaprilat against postischemic renal failure.

Prolonged intraoperative renal ischemia requires modalities to reduce the incidence of acute tubular necrosis, but there exists no definitive prophylactic regimen. We studied the effects of enalaprilat, an angiotensin-converting enzyme inhibitor, in an attempt to identify such a protective drug. Thirty-four mongrel dogs underwent 90 min of bilateral renal pedicle clamping. Group I was a control of 6 animals. Group II comprised 10 animals who received 12.5 g iv mannitol 15 min prior to clamping and 1 mg/kg iv furosemide immediately after clamp removal. Group III also comprised 10 animals who received enalaprilat 1 mg/kg iv enalaprilat each 15 min prior to clamp placement. Group IV consisted of 8 dogs, each of which received 12.5 g mannitol and 1 mg/kg iv enalaprilat 15 min prior to clamping and 1 mg/kg iv furosemide immediately upon removal of the clamps. Serum blood urea nitrogen (BUN) and creatinine levels were drawn preoperatively and at 12, 24, 48, and 72 hr postoperatively in each animal. The serum BUN levels in group III were significantly lower than those in group I at all times postoperatively (P < 0.05) and were not significantly different from those of group II at any time postoperatively. Similarly, the serum creatinine levels in group III were significantly lower than those of group I (P < 0.05) and were not significantly different from those in group II at any time postoperatively. Neither the serum BUN nor the serum creatinine levels in group IV were different from those of group I at any time postoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)

Occult functioning insulinomas: which localizing studies are indicated?

BACKGROUND: An occult insulinoma refers to a biochemically proven tumor with an anatomic site that remains indeterminate before operation. The amount of radiologic localization for such patients is debatable. METHODS: Sixty-five patients with sporadic insulinomas were surgically treated at the Mayo Clinic between January 1980 and December 1990. True occult tumors were present in 31% of these patients (n = 20). Thirty-eight negative preoperative localization studies were performed, with 10 patients undergoing more than one study. A benign adenoma was found in 19 patients when they underwent exploratory operation, whereas one patient had malignant disease with hepatic metastases. Thirteen patients underwent intraoperative ultrasonography with a 7.5 MHz real-time high-resolution transducer. RESULTS: Solitary lesions were successfully removed either by enucleation or by distal pancreatectomy in all 19 patients with benign disease. CONCLUSIONS: This high success rate in the management of occult insulinomas suggests that extensive preoperative radiologic investigation is neither indicated nor cost-effective.