Test differentiates insulinoma from diffuse nesidioblastosis

Last Updated: 2015-09-04

By Reuters Staff

NEW YORK (Reuters Health) - Selective arterial calcium stimulation (SACST) with hepatic venous sampling can differentiate insulinoma from diffuse nesidioblastosis, report researchers from the Mayo Clinic, Rochester, Minnesota.

"Patients with endogenous hyperinsulinemic hypoglycemia and negative or inconclusive noninvasive imaging present a diagnostic and management challenge as both occult insulinoma and noninsulinoma pancreatogenous hypoglycemic syndrome (NIPHS) resulting from diffuse nesidioblastosis must be considered in the differential diagnosis," note Dr. Scott Thompson and colleagues.

"SACST with hepatic venous sampling is an interventional radiologic technique used preoperatively to localize or regionalize occult insulinoma with a sensitivity >90% in multiple large series. The SACST technique is based upon the observation that exogenous intraarterial calcium differentially stimulates the release of insulin from abnormal pancreatic beta cells but not normal beta cells," they explain.

To gauge the ability of SACST to differentiate insulinoma from diffuse nesidioblastosis, the Mayo team reviewed data from 116 patients with biochemical evidence of endogenous hyperinsulinemic hypoglycemia and negative or inconclusive noninvasive imaging who underwent SACST prior to pancreatic exploration. Forty-two patients were later confirmed (surgically and pathologically) to insulinoma, while 74 had nesidioblastosis.

The team found that the mean maximum hepatic venous insulin concentration (mHVI) was 22 times higher and the average relative-fold increase in hepatic venous insulin concentration (rHVI) was nearly 4 times higher in patients with insulinoma relative to those with diffuse nesidioblastosis.

"Importantly, the ROC curves demonstrated that both mHVI and rHVI could differentiate insulinoma from nesidioblastosis with high specificity," the researchers reported in the Journal of Clinical Endocrinology and Metabolism online August 27. "Of note, the AUC was higher for mHVI compared to rHVI, 0.94 and 0.83, respectively, suggesting that mHVI has a slightly better diagnostic performance than the rHVI."

"Given the high specificity of both the mHVI and rHVI for differentiating occult insulinoma from diffuse nesidioblastosis, SACST may be useful for identifying only those patients with a high likelihood of an occult insulinoma for pancreatic exploration while preventing patients with diffuse nesidioblastosis from undergoing unnecessary surgery prior to a trial of conservative management," the researchers conclude.

They say further studies are needed to validate their findings to "better define the role of SACST when clinicians are faced with a patient with endogenous hyperinsulinemic hypoglycemia and negative or inconclusive localization studies."

The study had no commercial funding and the authors have no disclosures.

SOURCE: http://bit.ly/1KuoX0u

J Clin Endocrinol Metab 2015.