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Glucagon
Last reviewed: 23.04.2024
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Glucagon - A-cell pancreatic tumor that produces glucagon, is clinically manifested by a combination of characteristic skin changes and metabolic disorders. The syndrome of glucagonoma was deciphered in 1974. S. N. Mallinson et al. In 95% of cases, the tumor is intrapancreatic, in 5% - extrapancreatic. There were only cases of solitary tumors.
More than 60% of patients it malignant. Sometimes glucagonoma produces other peptides - insulin, PP. The diagnosis is established with an increase in glucagon levels and instrumental studies. The tumor is identified with CT and endoscopic ultrasound. Treatment of glucagonoma is surgical resection.
[Symptoms of glucagon
Because glucagonomes secrete glucagon, the symptoms of glucagon are similar to diabetes mellitus. Often there are weight loss, normochromic anemia, hypoaminoacidemia and lipid lowering, but the main distinctive clinical feature is a chronic rash that affects the limbs, often associated with a smooth, shiny, bright red color and cheilitis. Skin peeling, hyperpigmentation, erythematous lesions with superficial necrolysis are called necrolytic migratory erythema.
In most cases, patients have a characteristic migrating necrolytic erythema. It begins as maculopapular erythema, then goes into bulbous dermatosis. Moreover, the bubble-like upward layers of the epidermis are destroyed. In the neighborhood with the old, new elements arise. The cure comes through hyperpigmentation. Skin rashes appear more often in the abdomen, thighs, lower legs. The pathogenesis of skin changes is unclear. Their relationship with hyperglycemia and hypoacidemia, observed in patients with glucagonoma, is not excluded. Both hyperglycemia and hypoacidemia are a consequence of increased gluconeogenesis in the liver caused by an elevated glucagon level, and the plasma amino acids also turn into glucose.
Pathological glucose tolerance is due to the hyperglycemic effect of glucagon both due to neoformation of glucose, and due to enhanced glycogenolysis.
Often, patients develop very painful glossitis and stomatitis. Their pathogenesis is incomprehensible. There is also a pronounced stasis in the small and large intestine, associated with inhibition of the intestinal motility by the peptide.
Diagnostics of glucagon
The decisive evidence of glucagonoma (in the presence of appropriate clinical manifestations) is the detection in the plasma of high concentrations of glucagon (normal value below 30 pmol / l). However, moderate increases in the hormone can be observed with kidney failure, acute pancreatitis, severe stress and fasting. Correlation with symptoms is necessary. Patients should perform CT of the abdominal cavity and endoscopic ultrasound; if CT is uninformative, MRI can be used.
What do need to examine?
How to examine?
What tests are needed?
Treatment of glucagon
Radical removal of glucanoma can be done only one of the 3 patients with glucagonoma. Resection of the tumor leads to regression of the symptoms. Treatment of glucagonoma with streptozotocin and / or 5-fluorouracil without previous surgical intervention yields less comforting results.
Incompatible tumors, the presence of metastases or recurrent tumors are subject to combined treatment with streptozocin and doxorubicin, which lower the levels of circulating immunoreactive glucagon, lead to regression of symptoms and improve the condition (50%), but hardly affect the survival time. Octreotide injections partially suppress glucagon secretion and reduce erythema, but glucose tolerance can also decrease due to decreased insulin secretion. Octreotide quickly enough leads to the disappearance of anorexia and weight loss caused by the catabolic effect of glucagon excess. With the effectiveness of the drug, patients can be transferred to the prolonged octreotide 20-30 mg intramuscularly once a month. Patients taking octreotide should additionally take pancreatic enzymes because of the overwhelming effect of octreotide on the secretion of pancreatic enzymes.
There have been reports of a successful reduction in liver metastases by embolization of the hepatic arteries with gelatin foam, directly administered by catheterization.
To treat skin changes prescribe zinc preparations. Local applications, oral or parenteral use of zinc lead to regression of erythema, but erythema may resolve after simple hydration or intravenous administration of amino or fatty acids, suggesting that erythema is caused uniquely not by zinc deficiency.
What is the forecast for glucagon?
Glucagon is rare, but like other tumors from islet cells, the primary tumor and metastatic lesions have a slow growth: usually the survival time is about 15 years. Eighty percent of glucagon is cancerous. The average age of patients with symptoms is 50 years; 80% are women. In some patients there is a type I of multiple endocrine neoplasia.