Introduction: The Insulin Autoimmune Syndrome (IAS or Hirata Disease) is rare among children. Non-ketotic hyperinsulinaemic hypoglycemia and the presence of insulin auto-antibody (IAA) are the conditions to diagnose the syndrome. The occurrence of hypoglycemia is due to the binding of the antibody to the insulin molecule at the immediate postprandial, followed by this binomial dissociation, which releases free insulin on serum and triggers symptomatic hypoglycaemia.
Case report: A 6-year-old boy was followed by symptomatic hypoglycemia. Seizures since 7 months old were treated and controlled with anticonvulsants until the age of five, when raised hypoglycemia symptoms. Several hospitalizations, some highlighted exams: random glycemia 21 mg/dL (1.16 mmol/L), insulin 34.7 μU/mL, other critical sample exams were negative, abdominal MRI was normal. No improvement after taken diazoxide, somatostatin, hydrochlorothiazide and glucagon. As he did not improve, and there was still a suspect of exogenous insulin, new exams and a new hospitalization occurred: glycemia 26 mg/dL (1.44 mmol/L), insulin 686.7 μu/ml. Even though his mother was kept away from him, the insulin level increased to > 1000 μU/ml, c-peptide was 5.1 ng/ml (1.1 4.4), sulphonylurea dosage was negative, and two extended OGTT were performed, ranging insulin 4071000μU/ml, C-peptide 1.55.2 ng/ml and glycaemia 21112 mg/dl (1.166.2 mmol/l). Insulin antibody was found, associated to the insulin molecule, which resumes the syndrome. As soon as dietary and physical activities recommendations were followed, there had been less hypoglycemic episodes.
Conclusion: To exclude factitious hypoglycemia, four hospitalisations and judicial separation of mother and child were necessary to prove the mother was not giving inadvertently insulin to his child. Only when IAA was performed, which set the presence of autoantibodies bound to native human insulin, the diagnosis was elucidated. As IAS is usually related to previous exposure to drugs, this case is considered a novel insight into clinical practice.
01 - 03 Oct 2015
European Society for Paediatric Endocrinology