Disaccharidase deficiency

Introduction to disaccharidase deficiency This disease, also known as disaccharid intolerance, refers to various congenital or acquired diseases, which makes the intestinal mucosal brush-like disaccharidase deficiency, which causes the digestive and absorption of disaccharide to be disordered. When eating foods containing disaccharide A series of symptoms and signs that occur. basic knowledge The proportion of illness: 0.003% Susceptible people: no special people Mode of infection: non-infectious Complications: vomiting in children

Cause of disaccharidase deficiency

(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 reasons, disaccharidase is deficient, resulting in digestive absorption of disaccharide leading to diarrhea, clinical 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 isomaltose is secondary. Studies have shown that the enzyme is defective in the treatment of cells. In the endoplasmic reticulum, the enzyme complex is blocked in the Golgi complex, and the altered enzyme is transported to the cell surface. Due to the above various factors, the single gene disease can be heterogeneous. On chromosome 3q, it belongs to autosomal recessive hereditary disease. The homozygous has symptoms all the time. The heterozygotes can only disappear after the symptoms in infancy. The fresh yeast or live yeast can relieve the symptoms.

The gene of human lactase phlorizin hydrolase is located on chromosome 2, and when the baby's 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. Adult lactase deficiency is at this level. After weaning Lactase is gradually reduced, and it is easy to cause diarrhea when taking milk. The lack of this enzyme is related to heredity, accounting for 5% to 30% of Caucasians, and 75% of people of color, including Asians and Africans. Sucrose-isomaltase deficiency can be reduced to 10% to 20% of normal, intestinal mucosa is normal, the cause is still unknown, in addition, in the gastrointestinal infection, disaccharidase can also be temporarily secreted insufficiently.

Disaccharidase deficiency prevention

1. A small amount of dairy products. Even if the lactase is deficient in the individual, a small amount of milk (120ml to 240ml) can be tolerated without symptoms of intolerance. Limit the total amount of lactose intake in a day, generally limited to 12 grams of lactose. A small amount of food can also reduce the lactose intolerance reaction, and it is better to consume less than 250ml at a time. Lactose intolerance can be avoided by taking a reasonable interval and daily intake of total milk each time you drink milk.

2. It is not advisable to drink milk on an empty stomach. Those who have lactose intolerance should not drink milk on an empty stomach in the morning. Drinking milk while eating other foods, such as dairy products, can be reduced or not with lactose intolerance when consumed with meat and fat-containing foods.

Disaccharidase deficiency complications Complications, vomiting in children

Pediatric disaccharidase deficiency has a great impact on infants and young children. Common complications include diaper rash, vomiting, growth retardation, chronic diarrhea that is difficult to treat in children, calcium deficiency, zinc deficiency, iron deficiency and anemia. In severe cases, the induced complications can endanger the child's life. Adult disaccharidase deficiency can cause diarrhea. Generally does not lead to more serious complications.

Symptoms of disaccharidase deficiency Common symptoms Abdominal discomfort, abdominal distension, abdominal pain, sucrose-isomalt... Amino aciduria, trehalase, lack of diarrhea and diarrhea

When lactase is deficient, it can cause abdominal sputum, abdominal pain, or colic after taking milk or lactose. The stool of the diarrhea is watery, the acid smell is foamy, and the symptoms disappear after stopping the lactose-containing food. The patient is generally in good condition. If there is no history of intestinal surgery, there is no steatorrhea, sucrose, and isomaltase deficiency, causing diarrhea after taking sucrose and starch. The symptoms are similar to those of lactase deficiency.

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 different from congenital lactase deficiency, which is autosomal dominant, with fulminant diarrhea after starting feeding, acidic stool with watery vesicles, and diarrhea Can cause vomiting, dehydration, renal tubular acidosis, double diabetes, amino aciduria, cataract, liver and brain damage, such as diagnosis can cause death, stop diarrhea after breastfeeding, lactose-free urine and amino aciduria.

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

(4) Sucrose-isomalt malabsorption: It is caused by the lack of sucrose -dextrinase. Because the unabsorbed sucrose causes excessive osmotic pressure and fermented diarrhea in the intestinal lumen, the feces can be acidic, and the fecal pH can be Up to 4.0 to 5.0, there is sour taste, the amount is too much, the baby has severe diarrhea, but the adult has only stomach discomfort. After eating sweets and fruits, symptoms will appear. It is said that the Eskimo suffers from this disease, accounting for about 10% of the population. But generally asymptomatic.

(5) Trehalase deficiency: trehalase deficiency is rare. Patients suffer from abdominal pain, diarrhea, flatulence and vomiting after eating sputum. The stool is often watery. The mushroom contains trehalose and trehalose. It 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.

Examination of disaccharidase deficiency

1. Fecal examination: acidic stool, pH 5.0 ~ 6.0.

2. Lactose tolerance test: lactose 50g warm water 400ml fasting, take blood before the service and 15, 30, 60, 90 and 120min after the blood test, blood pressure in the test and within a few hours after the test, observe the patient's symptoms And check the nature of feces, blood glucose examination increased >1.4mmol / L is normal, <1.1mmol / L is abnormal, in 1.1 ~ 1.4mmol is not certain, patients with abnormal lactose test, during the test or in the trial The following symptoms often occur: colic (45.4%), diarrhea (36.4%), bloating (18.2%), and 66.7% of the above symptoms.

3. Lactose hydrogen breath test: oral lactose 1g / kg, exhaled hydrogen exceeds baseline 20 × 10-6 shows lactose malabsorption, lactose fermentation in the intestinal lumen produces excessive water, lactase is genetically regulated, I The type is lactase phlorizin hydrolase at the mRNA level; type II is abnormal after post-translational treatment and retention in the endoplasmic reticulum, this low lactase is autosomal recessive.

4. Small intestinal mucosa biopsy: small intestinal mucosal activity test lactase, showing low vitality.

Diagnosis and identification of disaccharidase deficiency

diagnosis

According to the clinical manifestations, the disease should be suspected, but the diagnosis is still necessary for the determination of pancreatic enzyme activity in the intestinal mucosa and the tolerance test for sugar. The diagnosis can be made according to the treatment response, and the symptoms can be alleviated after fasting the corresponding sugar.

Differential diagnosis

Should be excluded from a variety of secondary lactase deficiency such as celiac disease, extensive small intestine resection, whipple disease, Crohn disease, Giardia lamblia, intestinal lymphosarcoma, small intestinal malignant lymphoma and other diseases (such as Malabsorption caused by alcohol, neomycin, and cholestyramine.

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