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- Nesidioblastosis (NB) is a disease characterized by hyperfunctioning pancreatic β cells, usually associated with hypoglycemia in the presence of high endogenous insulin levels. It is necessary to exclude insulinoma or exogenous insulin of sulfonylurea administration when making the diagnosis.
- Most commonly described in neonates and children, but recent studies have shown an increased number of cases in adults
- Focal NB: confined to one discrete area of the pancreas
- Diffuse NB: All or most islet cells are affected.
- Most common cause of persistent hyperinsulinemic hypoglycemia in neonates
- Synonym(s): noninsulinoma pancreatogenous hypoglycemia (NIPHS); persistent hyperinsulinemic hypoglycemia of infancy (PHHI); congenital hyperinsulinism; islet cell hyperplasia
Few data available on the incidence of disease
- Sporadic: 1/30,000 to 1/50,000 live births
- Familial: 1/2,500 births have been seen.
- Adults: 0.5–15% of organic hyperinsulinemias
- Annual incidence is 0.09/100,000.
- Peaks in 5th decade of life
Etiology and Pathophysiology
NB involves hyperplastic pancreatic β cells that hyperfunction and cause excessive insulin secretion. KATP channel activity results with a constant insulin release:
- Focal NB: accounts for up to 40% of cases and consists of a discrete area of the pancreas with adenomatous hyperplasia of the islet cells
- Diffuse NB: Most or all β cells in the pancreas show hyperplasia.
- Most cases have a genetic predisposition; in adults, may involve dysregulation
- Increase in expression of IGF-2, IGF-1 receptor-α and TGF-β in islet cells from NB patients compared with controls
- Associated with gastric bypass surgery; has been associated with other upper gastrointestinal surgeries; elevated levels of GLP-1 in response to rapid presentation of nutrients to the distal jejunum (1)
- Complex AR/AD mutations on ABCC8 and KCJN11 genes on chromosome 11 have been found in focal and diffuse NB (2).
- More recent discoveries:
- HADH1: Studies have shown good response with diazoxide (AR).
- GK: poor response with diazoxide (AD)
- GLUD1: associated with high ammonia levels, also called HI/HA syndrome (AD)
- HNF4A: has shown spontaneous resolution in a few cases (3)
- Infants/children: likely a genetic predisposition to this disorder
- Adults: NB may also be genetically linked. However, there has been an association with gastric bypass surgery (1).
- Genetic counseling may be of benefit to families affected by this disease. No clear guidelines exist for preconception genetic counseling.
- Adults who are considering gastric bypass surgery should be cautioned.
Commonly Associated Conditions
- Insulinoma (most common)
- MEN1 syndrome