Nesidioblastosis is a rare medical condition characterized by the overproduction of insulin by the pancreas, leading to dangerously low blood sugar levels, known as hypoglycemia.
What is Nesidioblastosis?
Nesidioblastosis involves an abnormal growth or proliferation of the insulin-producing beta cells within the pancreas. These beta cells, normally found in clusters called islets of Langerhans, become overactive and secrete insulin without proper regulation.
The condition can manifest in two primary forms: focal and diffuse. Focal nesidioblastosis involves an abnormal concentration of beta cells in a specific, localized area of the pancreas. In contrast, diffuse nesidioblastosis features the widespread distribution of these abnormal beta cells throughout the entire pancreas. Insulin’s role is to help glucose from food enter cells for energy, but excessive insulin clears glucose from the bloodstream too rapidly, causing the body’s main energy source to become critically low.
Identifying the Symptoms
The clinical manifestations of nesidioblastosis primarily stem from hypoglycemia, which can present with a wide range of symptoms due to the brain’s reliance on glucose for energy. Symptoms can vary in severity and may include confusion, weakness, excessive sweating, and heart palpitations. Individuals may also experience dizziness, shakiness, and intense hunger as blood sugar levels fluctuate.
In infants, where nesidioblastosis is a more common cause of persistent hyperinsulinemic hypoglycemia, symptoms can include irritability, lethargy, and poor feeding. More severe or prolonged episodes of low blood sugar, particularly in infants and young children, can lead to seizures and, in some cases, permanent brain damage. The non-specific nature of these symptoms often makes diagnosis challenging, as they can mimic other common conditions.
How Nesidioblastosis is Diagnosed
Diagnosing nesidioblastosis typically begins with blood tests conducted during an episode of low blood sugar. These tests measure glucose, insulin, and C-peptide levels. In nesidioblastosis, low blood glucose is accompanied by inappropriately high levels of insulin and C-peptide, indicating excessive insulin production by the body. A supervised fast is often performed to confirm the presence of hyperinsulinemic hypoglycemia, as it allows medical professionals to observe the body’s response to prolonged periods without food while monitoring blood sugar and hormone levels.
To distinguish nesidioblastosis from other causes of hyperinsulinemic hypoglycemia, such as an insulinoma (a tumor that secretes insulin), more advanced diagnostic imaging techniques are utilized. These can include computed tomography (CT) scans and magnetic resonance imaging (MRI) of the pancreas to identify any masses. Positron emission tomography (PET) scans can also help localize areas of abnormal beta cell activity.
In cases where imaging is inconclusive, particularly to differentiate focal from diffuse disease, a selective arterial calcium stimulation test (SACST) may be performed. Ultimately, a definitive diagnosis often relies on histological examination of pancreatic tissue obtained through biopsy or during surgery. Genetic testing can also play a role, especially in congenital forms, by identifying specific mutations linked to the condition.
Managing the Condition
The primary goal in managing nesidioblastosis is to maintain stable blood glucose levels and prevent recurrent episodes of hypoglycemia, which can have serious consequences. Medical management often involves medications designed to inhibit insulin release or suppress its secretion. Diazoxide is a commonly used medication that reduces insulin secretion. Another medication, octreotide, can suppress insulin secretion from the pancreas. Dietary modifications, such as frequent small meals rich in complex carbohydrates and proteins, can also help stabilize blood sugar levels.
For cases that do not respond sufficiently to medical therapy, surgical intervention may be necessary. Pancreatectomy, the surgical removal of part or all of the pancreas, is a common approach. The extent of the pancreatectomy depends on whether the nesidioblastosis is focal or diffuse.
For focal lesions, a partial pancreatectomy, where only the affected portion of the pancreas is removed, is the preferred treatment, often leading to a cure. In contrast, diffuse nesidioblastosis, involving the entire pancreas, typically requires a near-total pancreatectomy. This more extensive surgery aims to remove enough insulin-producing tissue to control hypoglycemia, but it carries a higher risk of long-term complications, including the development of diabetes due to insufficient insulin production. Long-term monitoring is crucial for individuals who undergo pancreatectomy to manage potential complications and ensure ongoing glucose control.