Hyperinsulinemic hypoglycemia in adults. Case reports and a short review

Abstract

Persistent hyperinsulinemic hypoglycemia (nesidioblastosis) not caused by an insulinoma is rare in adults. Morphologically no insulin secreting tumor is present. Keystones of diagnosis are not only low glucose levels but to maintain normoglycemia by use of intravenous glucose and the presence of high insulin and C-peptide levels. Noninvasive and invasive diagnostic techniques are required to rule out a hormone secreting tumor. Both conservative and/or surgical therapy are suggested to prevent damaging effects of repeated hypoglycemia. Two patients with frequent and serious episodes of hypoglycemia are reported. In the 34-year-old female symptoms appeared with sweating, dizziness, trembling, nervousness and serious neuroglycopenic signs. In the 22-year-old male the main complaint was tympany, a rare and unusual sign of hypoglycemia, and intense feeling of esurience. The 24-hour fasting test was positive in both cases, i.e. it had to be stopped because of symptomatic hypoglycemia. No insulinoma could be localized, despite extensive search, therefore in both cases the diagnosis of adult-onset nesidioblastosis was set up, despite lack of histological confirmation. Diazoxide therapy resulted in symptom-free life for both patients. Several diagnostic methods and treatment options are suggested for the rare disease nesidioblastosis to balance defective insulin secretion. However, once the decision is made in favour of surgical therapy, there is a thin line between successful treatment, persistence of the disease, and pancreatic insufficiency. Therefore it is worth considering to try conservative therapy especially when surgery is of high risk. Our cases suggest that diazoxide therapy is an effective and safe alternative in the treatment of adult-onset nesidioblastosis.