ESPE Abstracts

Background: It is critically important to correctly diagnose hyperinsulinemic hypoglycemia (HH) to avoid neurological sequelae. However, the diagnosis is not always easy in the critical care setting since some patients present with atypical biochemical profiles.

Objective and hypotheses: To delineate the range of biochemical data of HH patients at hypoglycemia to help establish a better diagnostic criteria.

Method: Biochemical data (blood glucose, insulin, β-hydroxybutylate, free fatty acids, ammonia, lactate, and pyruvate) at hypoglycemia (<3 mmol/l) were collected from 302 patients with HH (167 transient, 135 persistent). Of these, 127 were obtained from the datasheets for mutational analyses conducted in our laboratory and other 175 were obtained from the national survey we conducted in Japan. As a control, we collected similar data from 29 non-HH patients who underwent controlled fasting tests in our institute. These data were statistically analysed to define the ranges and cutoffs to diagnose HH. In addition, clinical details of atypical patients were obtained from the medical charts.

Results: Most of the severely affected patients present with typical biochemical profile of HH whereas less severely affected patients or patients with other comorbidities often present with atypical results. Insulin as high as 2–7 μU/ml was observed in non-HI patients. On the other hand, HH patients could present with insulin <0.5 μU/mL, β-hydroxybutylate up to 2.1 mEq/l, and free fatty acids up to 1.7 mEq/l. One of these patients responded dramatically with diazoxide. In addition, a number of patients without GLUD1 mutation initially present with hyperammonemia.

Conclusion: No single cutoffs can diagnose all patients with HH especially when they present with mild symptoms or they have comorbidities. Initial hyperammonemia should be retested before diagnosing hyperinsulinism-hyperammonemia syndrome. Short trial of diazoxide might be considered in atypical patients.