Factitious hyperinsulinemic hypoglycemia in infancy: diagnostic pitfalls

Factitious Hypoglycemia in an Infant With Undetectable Exogenous Insulin by a Commercial Insulin Immunoassay: A Diagnostic Pitfall

Factitious hypoglycemia in infancy is a rare, life-threatening manifestation of Munchausen syndrome by proxy (MSBP). The hallmark of such presentation is the detection of low c-peptide combined with high insulin at the time of hypoglycemia. We report the case of a male infant who presented with recurrent severe unexplained hypoglycemic episodes since the age of six months. Two of his siblings had similar unexplained hypoglycemia episodes at a young age. He was extensively investigated, and all were normal, for endocrine and metabolic etiologies. He underwent fundoplication and insertion of a gastrostomy tube with multiple lengthy hospital admissions. His mother had diabetes and was on insulin treatment; she also had mental health issues with family-related social stressors. His hypoglycemic attacks resolved once separated briefly from his mother on the ward, raising our suspicion of MSBP. The exogenous administration of insulin was only confirmed following a scheduled change of our local Insulin assay in our laboratory when his insulin was detectable with low C-peptide on one of his typical attacks. Apparently, our previous insulin immunoassay lacked sensitivity for his mother's long-acting insulin. We are reporting this case to raise awareness about this potential diagnostic pitfall.

Hyperinsulinaemic hypoglycaemia:genetic mechanisms, diagnosis and management

Hyperinsulinaemic hypoglycaemia (HH) is characterized by unregulated insulin secretion from pancreatic β-cells. Untreated hypoglycaemia in infants can lead to seizures, developmental delay, and subsequent permanent brain injury. Early identification and meticulous managementof these patients is vital to prevent neurological insult. Mutations in eight different genes (ABCC8, KCNJ11, GLUD1, CGK, HADH, SLC16A1, HNF4A and UCP2) have been identified to date in patients with congenital forms of hyperinsulinism (CHI). The most severe forms of CHI are due to mutations in ABCC8 and KCJN11, which encode the two components of pancreatic β-cell ATP-sensitive potassium channel. Recent advancement in understanding the genetic aetiology, histological characterisation into focal and diffuse variety combined with improved imaging (such as fluorine 18 L-3, 4-dihydroxyphenylalanine positron emission tomography 18F-DOPA-PET scanning) and laparoscopic surgical techniques have greatly improved management. In adults, HH can be due to an insulinoma, pancreatogenous hypoglycaemic syndrome, post gastric-bypass surgery for morbid obesity as well as to mutations in insulin receptor gene. This review provides an overview of the molecular basis of CHI and outlines the clinical presentation, diagnostic criteria, and management of these patients.

Persistent hyperinsulinemic hypoglycemia with left ventricular hypertrophy and dysrhythmia: a case report

Persistent hyperinsulinemic hypoglycemia in neonatal period is characterized by insulin hypersecretion. The major feature is severe hypoglycemia, generally unresponsive to routine medical treatment. Subtotal or total pancreatectomy is performed in unresponsive cases. In this case report, we present a newborn with persistent hypoglycemia unresponsive to medical treatment with dysrhythmic left ventricular hypertrophy. The insulin/C-peptide ratio was 58 as a confirmation of diagnosis. Since hypoglycemia persisted after the initial medical treatment, a subtotal pancreatectomy was performed followed by near-total pancreatectomy. A histologic examination revealed diffuse insulin islets. At the 70th post-natal day, death occurred due to heart failure and ventricular dysrhythmia. To our knowledge, severe dysrhythmia and left ventricular hypertrophy in persistent hyperinsulinemic hypoglycemia (PPH) is identified in the patient.

Criminal Poisoning: Munchausen by Proxy

The diagnosis and subsequent prosecution of Munchausen by proxy (MBP) cases require the collaborative teamwork of health care teams, laboratory personnel, law enforcement, and social services. Poisoning occurs in a significant number of the MBP cases with a diverse variety of agents used. To aid laboratory professionals in determining the appropriate toxicology tests to perform in such criminal cases, health care professionals must focus their testing requests on substances that correspond to the victim's signs, symptoms, and ancillary test values. This article reviews MBP, with particular focus on poisoning agents that have been used in past reported cases.

Factitious hyperinsulinism leading to pancreatectomy: severe forms of Munchausen syndrome by proxy

Clinical history and inappropriate insulin secretion during hypoglycemic episodes permit the diagnosis of hyperinsulinism. We report 2 cases of factitious hyperinsulinism leading to partial pancreatectomy. Case 1 was an 8-year-old girl who presented with severe hypoglycemia and elevated insulin and C-peptide levels. Catheterization of pancreatic veins was performed to localize the excess insulin secretion. Insulinoma was suspected, and partial pancreatectomy was performed. Ten days after surgery, severe hypoglycemia recurred with severely elevated plasma insulin levels (x100) but very low C-peptide plasma levels, suggesting factitious hyperinsulinemia. Hypoglycemic episodes before surgery were provoked by oral sulfonamides; postoperative episodes were caused by parenteral insulin. Falsified prescriptions for sulfonamides and insulin by the mother, a nurse, were found. Case 2 was a 6-month-old girl who presented with seizures and hypoglycemia but had a symptom-free interval of many months afterward. At 2 years of age, repeated hypoglycemic seizures and elevated insulin plasma levels suggested congenital hyperinsulinism. C-peptide plasma level, measured once, was normal, but blood sampling was performed 15 minutes after a hypoglycemic episode. Partial pancreatectomy was performed. Two weeks after surgery, hypoglycemic seizures recurred, and the patient was admitted for pancreatic vein catheterization. This investigation was performed during hypoglycemia and revealed high insulin levels and undetectable C-peptide levels, suggesting factitious hypoglycemia. Insulin/C-peptide ratio analysis is crucial to assess factitious hypoglycemia, although sulfonamide-induced hypoglycemia is not thereby detected. One percent (2 of 250) of all cases of hyperinsulinemic hypoglycemia in our unit have been identified as Munchausen syndrome by proxy. Atypical disease history should raise the question of factitious hypoglycemia.