Sucrose-Isomaltose Malabsorption

Introduction Sucrose-isomalt malabsorption, also known as disaccharide intolerance, refers to a variety of congenital or acquired diseases, which makes the intestinal mucosal brush-like disaccharidase deficiency, which causes digestive and absorption of disaccharide, and contains double A series of symptoms and signs that occur when sugary foods. Infants may have insultainase and isomaltase deficiency due to genetic factors. The defect of sucrose-isomalt malabsorption is mainly in sucrose, and the isomaltose defect is secondary.

Cause

(1) Causes of the disease

There are many disaccharidases in the small intestinal mucosa of normal people. For example, lactase can decompose lactose into galactose and glucose. Maltase can decompose maltose into glucose and isomaltose. Isomaltase can decompose isomaltose into two molecules. Glucose; Sucrose can decompose sucrose into glucose and fructose; and trehalase can decompose trehalose into two molecules of glucose. For some reason, the disaccharide enzyme is deficient, and the digestive absorption of the disaccharide is hampered. Clinically, this disease is not uncommon, but it is often ignored.

(two) pathogenesis

Infants may have insultainase and isomaltase deficiency due to genetic factors. The defect of sucrose-isomalt malabsorption is mainly in sucrose, and the isomaltose defect is secondary. Studies have shown that the enzyme is defective in intracellular processing and accumulates in the endoplasmic reticulum. The enzyme complex is blocked in the Golgi complex, while the altered enzyme is transported to the cell surface. Due to the above various factors, this single gene disease can be heterogeneous. The enzyme gene is located on chromosome 3q and belongs to the autosomal recessive hereditary disease. Homozygous has symptoms throughout life, and heterozygotes can only disappear after symptoms in infancy. Give fresh yeast or live yeast to alleviate its symptoms.

The gene for human lactase phlorizin hydrolase is located on chromosome 2. When the infant's small intestinal mucosal epithelial brush border is deficient in lactase, watery diarrhea occurs after the first breastfeeding.

The most common deficiency of adult disaccharidase is lactase deficiency. Lactase activity is highest in neonates and can be reduced to 10% of its maximum in the future, at this level in adults with lactase deficiency. After the baby is weaned, the lactase is gradually reduced, and it is easy to cause diarrhea when the milk is taken. The lack of this enzyme is genetically related, accounting for 5% to 30% of Caucasians, and 75% of people of color, including Asians and Africans. The lack of sucrose-isomaltase can be reduced to 10% to 20% of normal, and the intestinal mucosa is normal. The reason is unknown. In addition, in the case of gastrointestinal infections, disaccharidase can also be temporarily secreted insufficiently.

an examination

Related inspection

Galactose tolerance test blood electrolyte test

When lactase is deficient, it can cause belching, abdominal pain, or cramping after taking milk or lactose. The stool of the diarrhea is watery, and the acid odor has foam. Symptoms disappeared after stopping the lactose-containing food. The patient is generally in good condition, such as no history of intestinal surgery, and generally no steatorrhea. When sucrose or isomaltase is deficient, it causes diarrhea after taking sucrose and starch, and the symptoms are similar to those of lactase deficiency.

According to the clinical manifestations, the disease should be suspected, but it is still necessary to determine the intestinal mucosal pancreatic enzyme activity and the tolerance test for sugar. It is still possible to make a diagnosis based on the treatment response, and the symptoms can be alleviated after fasting the corresponding sugar.

Differential diagnosis

Differential diagnosis of sucrose-isomalt malabsorption:

Sucrose-isomalt malabsorption should be associated with various secondary lactase deficiency such as celiac disease, extensive resection of small intestine, whipple disease, Crohn's disease, Giardia lamblia, intestinal lymphosarcoma, intestinal malignant lymphoma and other diseases And the absorption of certain drugs (such as alcohol, neomycin, cholestyramine) is mutually differentiated.

1. When lactase is deficient, after taking milk or lactose, it can cause abdominal sputum, abdominal pain, or cramping. The stool of heavy diarrhea is watery, and the acid smell has foam. Symptoms disappeared after stopping the lactose-containing food. The patient is generally in good condition, such as no history of intestinal surgery, and generally no steatorrhea. When sucrose or isomaltase is deficient, it causes diarrhea after taking sucrose and starch, and the symptoms are similar to those of lactase deficiency.

2. Clinical classification

(1) Congenital lactase deficiency: babies vomit soon after eating breast milk or milk, can not grow, dehydration, acidosis, lactoseuria and amino aciduria, serious condition, poor prognosis.

(2) Congenital lactose intolerance: This is a disease that is different from congenital lactase deficiency and belongs to autosomal dominant inheritance. After starting feeding, there was fulminant diarrhea, acidy stool with watery vesicles, and diarrhea. Can cause vomiting, dehydration, renal tubular acidosis, disaccharide, amino aciduria, cataract, liver and brain damage, such as diagnosis can cause death. The diarrhea disappeared after stopping the feeding, and there was no lactoseuria or amino aciduria.

(3) Acquired lactose intolerance in adults: After taking milk, it can cause watery acidity with abdominal distension and abdominal discomfort.

(4) Sucrose-isomalt malabsorption: It is caused by the lack of sucrose -dextrin enzyme, because the unabsorbed sucrose causes excessive osmotic pressure and fermented diarrhea in the intestinal lumen. The feces can be acidic, the pH of the feces can reach 4.0 to 5.0, there is sour taste, the amount is too much, the baby has severe diarrhea, and the adult has only stomach discomfort. Symptoms can occur after eating sweets and fruits. It is said that Eskimos have more people with this disease. It accounts for about 10% of the population, but it is generally asymptomatic.

(5) Trehalase deficiency: Trehalase deficiency is rare, and patients suffer from abdominal pain, diarrhea, flatulence and vomiting after eating mites. The stool is often watery. The mushroom contains trehalose, which is a kind of 1,-glucose-1--glucoside. The diarrhea lasts only for a few hours, and the fasting of the mushroom no longer occurs.

According to the clinical manifestations, the disease should be suspected, but it is still necessary to determine the intestinal mucosal pancreatic enzyme activity and the tolerance test for sugar. It is still possible to make a diagnosis based on the treatment response, and the symptoms can be alleviated after fasting the corresponding sugar.

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