What is Insulinoma?
An insulinoma is a tumor of the pancreas derived from the beta cells which while retaining the ability to synthesise and secrete insulin is autonomous of the normal feedback mechanisms. Patients present with symptomatic hypoglycaemia
which is ameliorated by feeding. The diagnosis of an insulinoma is usually made biochemically with elevated insulin, proinsulin and C-peptide levels and confirmed by medical imaging or angiography. The definitive treatment is surgery.
Insulinomas produce excessive amounts of insulin and this causes low blood sugar. The typical symptoms that patients complain about are related to the development of low bloods sugar and include tiredness, weakness, tremulous and hunger. Many patients have to eat frequently to prevent symptoms from the low blood sugar. Some patients may develop psychiatric symptoms because of the low blood sugar.
An insulinoma is a rare benign tumour of the insulin-producing cells of the pancreas. Such a tumour can produce abnormally high quantities of insulin so that the amount of glucose in the blood (which is reduced by insulin) can fall to dangerously low levels. This is called hypoglycaemia and, unless sugar is given immediately, the patient can potentially go into a coma and die.
What causes insulinoma?
The pancreas is an organ in the abdomen that releases the hormone insulin. Insulin is required to regulate blood sugar levels. Tumors of the pancreas that produce excessive amounts of insulin (hyperinsulinemia) are called insulinomas.
High insulin levels cause hypoglycemia, or low blood glucose (sugar). Hypoglycemia caused by insulinomas may be mild and lead to symptoms such as anxiety and hunger, but patients are also at risk for severe hypoglycemia, which can cause seizures, coma, and even death.
What are the symptoms of insulinoma?
Symptoms of insulinoma may include dizziness, disorientation and weight gain — often patients feel better after they eat, and so eat more frequently. Eighty-five percent of patients have blurred vision, palpitations, sweating and weakness, as hypoglycaemia produces adrenaline which causes these effects. Seizures are not uncommon.
The lack of food to the brain results in the signs seen which usually are periodic (they come and go on their own). The early signs are: depression, lethargy, blankly staring with poor response to sound or touch, salivating and pawing at the mouth (because they are nauseated), and periodic weakness, especially of the hind quarters. Sometimes enlarged spleens are seen. More severe signs are stupors, seizures, severe weakness, and coma.
How is insulinoma diagnosed?
A standard supervised fasting test is usually carried out for diagnosis - basically this looks at insulin production over a
period of time following the last "meal" (usually glucose). The patient will typically be in hospital for this period of time. As we see in RPA, ultrasound examinations are also used.
The diagnosis is made by simultaneous measurements of blood sugar and insulin levels in the blood. A low blood sugar with a high insulin level confirms the diagnosis. Once the diagnosis made based on the biochemical analysis then the physician will perform further studies to detect the tumor in the pancreas.
Since most of these tumors are small, detection of the tumor in the pancreas may be difficult. Some of the studies that are performed to detect the tumor include a detailed CT scan, MRI, octreotide scan, and an endoscopic ultrasound.
An experienced surgeon often detects these tumors even where they are not seen on radiological testing prior to surgery. Imaging the pancreas during the surgery directly with an ultrasound detects the majority of these tumors.
What're the treatments for insulinoma?
Insulinoma is a progressive disease requiring constant monitoring and care, as well as adjustments in medications. Either surgery, medications, or both will extend the life of your ferret about 2 years. Unlike adrenal tumors, surgery is not always an
option and will not necessarily provide a cure. This is because many tumors are very small and spread out over the pancreas. If there are obvious nodules, these can be removed surgically. Suspicious portions of the pancreas can also be removed in surgery, but incorrect pancreatic surgery can cause and inability to digest fat or even diabetes. If surgery is needed, the vet should also look for the commonly associated adrenal tumors while inside the ferret.
Surgery is the preferred treatment for insulinoma. The tumor is localized with diagnostic testing or surgical exploration. Solitary tumors are removed, but patients with multiple tumors usually require partial removal of the pancreas (partial pancreatectomy). At least 15% of the pancreas is left to avoid malabsorption due to lack of pancreatic enzymes.
If no tumor is found at surgery or a patient is not a candidate for surgery, the drug diazoxide may be given to lower insulin secretion and avoid hypoglycemia. A diuretic is always given with this medication to avoid retaining too much salt. Octreotide has also been used to suppress insulin secretion in some patients. Medical treatment is also used to stabilize the person prior to surgery.
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