ICD-11

Congenital isolated hyperinsulinism, or Persistent hyperinsulinaemic hypoglycaemia of infancy (PHHI) is defined by an inappropriate oversecretion of insulin by the endocrine pancreas that is responsible for profound hypoglycaemia, which requires aggressive medical and/or surgical treatment to prevent severe and irreversible brain damage. PHHI is a genetically heterogeneous disorder with two types of histological lesions: diffuse (DiPHHI) and focal (FoPHHI) which are clinically indistinguishable.

Persistent hyperinsulinemic hypoglycemia of infancy (PHHI) is the most common cause of hypoglycemia in early infancy. The inappropriate oversecretion of insulin by the endocrine pancreas is responsible for profound hypoglycemia, which requires aggressive medical and/or surgical treatment to prevent severe and irreversible brain damage. First-line therapy consists of diazoxide, but the majority of newborns are resistant to it and to other treatments (e.g., the somatostatin analog octreotide, nifedipine, leucine-restricted diet). PHHI is a genetically heterogeneous disorder with two types of histological lesions: diffuse (DiPHHI) and focal (FoPHHI) which are clinically indistinguishable. FoPHHI is characterized by focal adenomatous islet-cell hyperplasia. DiPHHI corresponds to hypertrophy of all the beta cells in the islets of Langerhans which leads to a functional abnormality of insulin secretion throughout the pancreas and involves several genes with different inheritance patterns. Distinguishing between focal and diffuse lesions is very important for the pediatrician in terms of outcome because the therapeutic approach and genetic counseling differ radically.