Sugar malabsorption in children

Introduction to sugar absorption in children Sugar malabsorption is mainly due to the lack of specific disaccharidase in the small intestinal mucosa, which makes the disaccharide in food not fully hydrolyzed into monosaccharides to affect its absorption, and occasionally the monosaccharide absorption disorder. Amylase is rare in addition to newborns and generally does not cause clinical problems. basic knowledge The proportion of illness: 0.001% Susceptible people: children Mode of infection: non-infectious Complications: malnutrition, electrolyte imbalance

Pediatric sugar malabsorption

(1) Causes of the disease

Sugar malabsorption can be divided into two categories: primary and secondary:

1. Primary glucose malabsorption: In primary glucose malabsorption, congenital lactase deficiency, sucrose-isomaltase deficiency, and glucose-galactose malabsorption are all autosomal recessive genetic diseases, clinically rare. Except for the lack of sucrose-isomaltase, the incidence of sucrose can be added to the diet, and the rest of the disease occurs soon after birth. The histology of small intestinal mucosa biopsy is normal, and the corresponding disaccharidase activity is decreased, glucose-galactose malabsorption is poor. The disaccharidase activity was normal, and the malabsorption was caused by the congenital deficiency of Na+-glucose and Na+-galactose carrier protein, and the fructose absorption of the sick child was good.

There are two other types of primary lactase deficiency, which are all physiologically deficient:

1 Developmental lactase deficiency: lactase activity is only 30% of full-term infants at 24 weeks, and then gradually increases until full-term delivery. Therefore, lactase activity in premature infants is low, lactose resistance is easy to occur. Bad.

2 Lack of late lactase: In general, the lactase activity of the intestinal epithelial brush border is sufficient in the lactating period of infants, and gradually decreases after 3 to 5 years old. Some children may cause lactase deficiency or lactose intolerance.

2. Secondary lactase deficiency and monosaccharide malabsorption: clinically more common, because lactase is distributed at the top of the small intestine villi, all diseases that can cause damage to the intestinal mucosal epithelial cells and their brush borders can be secondary to disaccharide Lack of enzymes, severe lesions, extensive, can also affect the absorption of monosaccharides, such as acute enteritis (especially involving the upper part of the small intestine, such as rotavirus enteritis, blue Giardia infection, etc.), chronic diarrhea, protein-calorie malnutrition , immunodeficiency disease, celiac disease and small bowel surgery injuries.

In the upper part of the jejunum, lactase is mainly found in the brush border of the epithelial cells at the top of the villus. The invertase is abundant in the villus, while the maltase is widely distributed in the intestine and is the most abundant. Therefore, lactose occurs when the small intestine is damaged. The enzyme is the most susceptible, and the recovery is the slowest, the most common clinical; maltase is the least susceptible, and the invertase is rare and rare, and only when the intestinal mucosa is seriously damaged, the activity is decreased. At this time, the lactase activity has been affected, and Often accompanied by a single sugar absorption disorder.

(two) pathogenesis

The carbohydrates ingested by the human body are mainly starch, lactose and sucrose. They must be digested and hydrolyzed into monosaccharides before being absorbed by the small intestine. The starches include both linear and branched chains, all of which are glucose multimers, saliva. And amylase in the pancreas, hydrolyzed starch, decomposed into maltose (containing 2 molecules of glucose), malt oligosperm (composed of several molecules of glucose) and dextrin, amylin on the brush border of intestinal epithelial cells (ie isomaltase) hydrolyzes dextrin molecules, which further hydrolyze maltose and eventually break down these sugars into glucose for absorption.

Both lactose and sucrose are disaccharides. Lactase in the brush border of small intestinal epithelium can decompose lactose into galactose and glucose. Sucrose can decompose sucrose into fructose and glucose. Glucose and galactose can be actively absorbed in the small intestine. It absorbs quickly and can reverse the concentration gradient, but consumes energy. Fructose is mainly absorbed by the carrier, and the absorption can not be reversed. The xylose (experimental) can only be absorbed by passive diffusion.

Sugar is absorbed more completely in the small intestine, but a small amount of unabsorbed sugar enters the colon, which can be decomposed by the intestinal flora (mainly bifidobacteria, followed by lactobacilli, etc.) and then absorbed.

Pediatric sugar malabsorption prevention

1. Strengthen health care during pregnancy to prevent premature birth.

2. Actively prevent and treat various intestinal diseases, especially infectious diseases and malnutrition, to prevent the occurrence of sugar malabsorption.

3, regular physical examination: to achieve early detection, early diagnosis, early treatment.

4, enhance physical fitness, improve their own immunity: pay attention to work and rest, more to participate in physical exercise, eat more fresh fruits and vegetables rich in vitamins.

Pediatric sugar malabsorption complications Complications, malnutrition, electrolyte imbalance

Often accompanied by malnutrition, water and electrolyte disorders, acidosis and so on.

Pediatric sugar malabsorption symptoms Common symptoms Abdominal discomfort Diarrhea, bowel, dehydration, immunodeficiency, bloating, baby, buttocks, red water, exhaust

Children with disaccharidase deficiency may have only laboratory abnormalities, but no clinical symptoms. Those with clinical symptoms due to poor glucose absorption, called glucose intolerance, and various glucose intolerances often show similar clinical symptoms. The basic pathophysiological changes are:

1. Unabsorbed sugar causes osmotic pressure in the intestinal lumen to cause osmotic diarrhea.

2. The sugar part is lost from the feces, and some of the organic acid and CO2, H2 and methane are produced by bacterial fermentation in the distal part of the ileum and in the colon. After being partially absorbed, these gases can be discharged by exhalation.

Therefore, sick children, especially infants and young children, after eating foods containing intolerant sugar, often manifest as watery stool diarrhea (called glycogen diarrhea), feces containing foam, with acid odor, acid stools irritating the skin easy to cause babies Hip red, severe cases of erosion, severe diarrhea often cause electrolyte imbalance such as dehydration acidosis, prolonged course can cause malnutrition, and some children with dehydration after correction, often have abnormal performance of eating hunger, fasting or diet removal After tolerating sugar, symptoms such as diarrhea can be quickly improved, which is one of the characteristics of this disease. The clinical symptoms of older children are often lighter, which can only be manifested as abdominal distension, increased exhaustion, abdominal discomfort, intestinal colic or bowel sounds. Break into.

Pediatric sugar malabsorption check

1. Blood routine and biochemical examination: Blood routine examination is often a large cell anemia, can also be positive cell anemia or mixed anemia, serum potassium, sodium, calcium, magnesium, phosphorus, etc. can be reduced, plasma albumin, cholesterol Phospholipids and prothrombin can also be reduced, and serum folic acid, carotene and vitamin B12 can be reduced in severe cases.

2. Screening test

(1) Determination of stool pH: Fresh stools in sugar-tolerant children have a pH of <6 and often less than 5.5.

(2) Fecal reducing sugar determination: Clinitest test paper, modified class reagent or lead acetate method can be used for reducing sugar determination, such as 0.005 indicating poor glucose absorption.

Take 1 part of fresh feces, add 2 parts of water and mix, centrifuge, take 1ml of supernatant, add 1 piece of Clinitest reagent, and obtain the concentration of reducing sugar by colorimetric with standard card, 0.5g/dl is positive, neonatal>0.75 The g/dl is abnormal, and the above supernatant may also be heated with a Benedicat solution to measure the reducing sugar.

Since sucrose is not a reducing sugar, 1 part of feces should be added with 2 parts of 1N HCl. After heating, the supernatant is taken. At this time, sucrose has been hydrolyzed into monosaccharides, and the reducing sugar can be measured according to the above method. Often in the colon has been broken down into reducing sugar by bacteria, so in fact, it is often not necessary to first add HCl hydrolysis, but if acid treatment, the fecal sugar is significantly increased than untreated, suggesting that the sick children have sucrose malabsorption.

Feces contain other reducing substances, such as vitamin C, which can be false positive.

3. Sugar-expiratory test: The method is sensitive, reliable, simple, and non-invasive, but the gas content of the exhaled hydrogen is determined by gas chromatography. The body itself cannot produce hydrogen, and the hydrogen in the breath is caused by the colon. The inner sugar is produced by bacterial fermentation. Normal people can completely absorb most of the absorbable sugar before reaching the colon, and the sugar that is not absorbed by intestinal bacterial fermentation is the only source of hydrogen in human exhalation. This principle can be used to determine the poor absorption of sugar by the small intestine.

Before and after ingesting certain test sugars, the hydrogen or 14CO2 in the breath is measured. After ingesting the test sugar, if the expiratory hydrogen is elevated or the expiratory 14CO2 is lowered, it indicates that the sugar is poorly absorbed, and can be fasted for 8 to 12 hours in the evening. After the test of hydrogen as a base, then oral test 2g / kg of sugar, up to 50g, some people advocate reducing the dose to 0.25 ~ 0.5g / kg, to reduce the symptoms of induced glucose tolerance, collected every half hour The content of hydrogen measured by breath is 2~3h. If the total amount of hydrogen exceeds the value of fasting time base 20×10-6ppm, it can be diagnosed as poor absorption of the tested sugar. The antibiotics can inhibit intestinal bacteria and can cause false negatives.

4. Small intestinal mucosal biopsy disaccharidase activity assay: The Crosby intestinal biopsy catheter can be inserted through endoscopy or orally, and the thin layer of intestinal mucosa can be cut by negative pressure for histological examination and direct determination of various disaccharidase contents, especially Conducive to the diagnosis of congenital glucose malabsorption, glucose inhalation, one or several disaccharidase activities decreased.

5. Lactose tolerance test: 50g oral lactose, blood glucose measurement every 30min, a total of 2h, normal people after oral lactose, than the fasting blood glucose increased by 1.1mmol / L (20mg / dl) or more; lactase deficiency The blood glucose curve is low, and lactose intolerance appears, but blood sugar can be affected by many factors. The result needs to be combined with clinical significance, and this test requires multiple blood draws, which has been used less frequently in recent years.

6. Determination of fecal sugar: The method can be used to determine the fecal sugar and distinguish different kinds of sugars, and the lead acetate method is used to determine the lactose in the feces. These methods have reference significance for diagnosis.

Intestinal X-ray examination, non-specific, but has a certain reference value for diagnosis, can help to detect intestinal morphological or functional changes, such as intestinal lumen enlargement, segmental distribution of tincture, change in emptying time, Intestinal folds and thickening.

Diagnostic identification of pediatric sugar malabsorption

diagnosis

1. The diagnostic criteria of ESPGAN in 1969: The diagnostic criteria established by the European Society for pediatric gastroenterology and nutrition (ESPGAN) in 1969. The malabsorption of sugar can be divided into two major categories: primary and secondary. Primary glucose malabsorption diseases include congenital lactose malabsorption, sucrose-isomaltase deficiency, glucose-galactose malabsorption, etc.; diseases causing damage to intestinal mucosal epithelial cells and brush borders, such as viral enteritis, chronic Diarrhea, protein-calorie malnutrition, immunodeficiency disease, small bowel surgery, etc., can cause secondary glucose malabsorption.

2. Glycytolerance: The phenomenon of clinical signs and symptoms of sugar malabsorption is called sugar intolerance. The clinical manifestation is that children have osmotic diarrhea after eating dairy food, which is watery stool and feces. The fat does not increase, the stool is sour, there is foam, often abdominal discomfort, abdominal distension, increased exhaustion, severe water, electrolyte and acid-base balance disorder, once you stop eating dairy food or remove intolerant sugar, The symptoms of diarrhea can be quickly relieved, which is one of the characteristics of this disease.

3. Laboratory examination of sugar malabsorption

(1) The stool pH is often <5.5, suggesting that the sugar is poorly absorbed.

(2) Determination of fecal reducing sugar: If 0.005, it indicates that the sugar is poorly absorbed.

(3) Sugar-exhalation test: After ingesting the test sugar, an increase in expiratory hydrogen or a decrease in exhaled 14CO2 indicates poor absorption of the test sugar.

(4) Determination of disaccharidase activity in small intestinal mucosa biopsy: in patients with poor glucose absorption, one or several disaccharidase activities were reduced.

(5) Lactose tolerance test: The lactose deficiency is low in blood glucose and lactose intolerance.

Differential diagnosis

Different from other malabsorption syndromes, such as fat malabsorption syndrome and protein malabsorption syndrome.

1. Non-tropical sprue (celiac disease): This disease, also known as glutin sensitive enteropathy or pediatric celiac disease, used to be called "primary malabsorption syndrome". May be related to genetic factors, the disease is familial, the child has a physique sensitive to gluten, and its pathogenesis is thought to be due to the lack of a peptidase in the intestine, causing a large accumulation of toxic peptides in the gluten to damage the intestines. It is caused by mucosal cells; some people think that due to immune abnormalities, after eating food containing wheat flour, humoral and cellular immune reactions occur in the body, causing intestinal mucosal damage and pathogenesis. The pathological changes of this disease mainly occur in In the jejunum, the jejunum villi become stiff, some fusion, some atrophy, or even disappear completely, the mucosa is flat, the mucosal epithelial cells change from column to cuboid, the number of brush border cells is reduced, the height is reduced or disappeared, and the mucosa is inherent. The layers are infiltrated with plasma cells and eosinophils.

The disease is more than 6 months after the addition of cereals, and gradually becomes sick. The appetite gradually declines, vomiting, and the amount of feces is large. It is grayish white corn paste, malodorous, contains foam and fat, does not increase or decrease in weight, and has a sad expression. Pale, abdominal swelling, muscle relaxation, due to poor absorption of nutrients such as protein, fat, fat-soluble vitamins, child growth and development stagnation, may have dystrophic edema, rickets or osteoporosis, anemia or bleeding tendency and other nutritional deficiencies Due to the decreased activity of many hydrolase enzymes in the brush border of small intestinal epithelial cells, glucose, galactose and fructose are poorly absorbed, resulting in hyperosmolar state in the intestinal lumen, causing hyperosmolar diarrhea. In severe cases, "crisis" occurs, showing no Appetite, vomiting, diarrhea, loss of water, acidosis or even shock.

Laboratory tests: can check fecal neutral fat and free fatty acids, xylose absorption test, fat absorption test and small intestinal mucosal biopsy; can also be used for therapeutic tests, that is, after stopping the wheat noodles for several days to several weeks, the symptoms are improved.

Treatment should be based on a wheat-free diet, that is, wheat, barley, oats, rye and other wheat products can be banned. Milk, rice, eggs, lean meat, beans, bananas, etc. can be used. Most patients have 1 week after treatment. Obvious symptoms improve, a few need half a year, no wheat gelatin diet should adhere to life, because the disease is long, high consumption, should give high heat, high protein diet, pay attention to vitamin and inorganic salts, serious cases, especially acute diarrhea Adrenal corticosteroids can be used to relieve symptoms when accompanied by severe dehydration.

2. Congenital chloride diarrhea: congenital chlorine-deficient diarrhea, also known as familial chloride diarrhea or Darrow-Gamble syndrome, is a rare autosomal recessive disease due to ileal congenital Lack of active absorption of Cl- and HCO3- exchange normal function, Cl- in the distal ileum and colonic dysfunction, a large number of stay in the intestinal lumen, so that the intestinal osmotic pressure increased, water into the intestinal lumen caused by diarrhea and a large number Chloride is discharged.

The disease occurs mostly in premature infants. The mother has a history of polyhydramnios during pregnancy, and the content of alpha-fetoprotein and bilirubin in the amniotic fluid is increased. The baby develops diarrhea soon after birth, and may have abdominal distension and hyperbilirubinemia. Significant weight loss, feces are watery, diarrhea is persistent, severe dehydration is easy to occur in mild infections, physical examination is common in children with developmental delay, and dehydration is performed. Other common causes of diarrhea should be ruled out in diagnosis, such as family Shi Ke earlier suggested the diagnosis of the disease, the stool contains a lot of chloride, about 30 ~ 100mmol / L (the chloride content of adult feces is only 7 ~ 20mmol / L), blood biochemical test blood potassium and blood chlorine are reduced, The blood pH is elevated, which is metabolic alkalosis, and there is little or no urine chloride in the urine.

The treatment is mainly to supplement enough water, oral potassium chloride 2 ~ 4mmol / kg per day to maintain normal blood pH and electrolyte content, but only improve the general condition, can not cure diarrhea.

3. Intestinal lymphangiectasia: Intestinal lymphangiectasia is a rare intestinal lymphatic abnormal disease, which can be congenital or acquired, congenital mostly caused by congenital malformation of lymphatic vessels Acquired, secondary to the pancreatitis, retroperitoneal fibrosis, constrictive pericarditis and other diseases.

Congenital onset in neonatal or infancy, often accompanied by abnormal lymphatic vessels in other parts, manifested as limb asymmetry edema, groin, posterior peritoneal lymph node dysplasia, or subcutaneous hemangioma, varicose veins, soft tissue and bone hypertrophy Etc, due to the rupture of lymphatic vessels in the intestinal lumen, resulting in loss of lymph, protein, fat, lymphocytes, steatorrhea, bloating, chyle-like ascites, loss of appetite, weight loss, fat-soluble vitamin deficiency, serum albumin Immunoglobulin, transferrin, protein-bound iodine decreased, peripheral blood lymphocytes were significantly reduced, X-ray showed diffuse roughness and thickening of small intestinal mucosa, gear-like, endoscopic duodenal mucosa thickening, The villi are scattered micro-papillary small nodules, small intestine biopsy, under the light microscope, the villi are shorter and more distorted than normal, and the lamina propria lymphatic vessels are obviously dilated.

The treatment of this disease, such as lymphatic vessel expansion is limited to a segment of the intestine, can be surgically removed radically, the general case should limit fat food and use medium chain triacylglycerol (directly into the hepatic vein after absorption) instead of long-chain fat (after absorption) Lymphatic vessels), acquired lymphangiectal distension is mostly caused by the primary disease, mainly to treat the primary disease.

4. cystic fibrosis of pancreas: pancreatic cystic fibrosis is an autosomal recessive systemic exocrine dysfunction disease, high incidence in European and American Caucasians, oriental yellow species Rarely, 80% of children have pancreatic enzymes, water and bicarbonate secretion reduction, common symptoms are severe steatorrhea, increased stool frequency, and more fat and special odor, due to fat absorption disorders can occur Symptoms of fat-soluble vitamin deficiency, such as vitamin A deficiency caused by corneal softening, vitamin K deficiency caused by bleeding tendency, etc., due to the discharge of a large amount of fat in the stool, gastric emptying, easy to starve, but the weight does not increase, growth and development stagnant, about 20% Neonatal meconium ileus or meconium peritonitis, older children may have constipation, intestinal obstruction and abdominal cramps, often have rectal prolapse, respiratory system with chronic cough, repeated upper respiratory tract infection, lung X-ray lesions may have Scattered atelectasis, emphysema, bronchiectasis or chronic interstitial pneumonia, can eventually develop into pulmonary fibrosis or pulmonary heart disease, due to the secretion of thick mucus by the systemic mucous glands The expansion of the gland tube and block the nozzle, can not drain outward, and finally lead to organ fibrosis, when the original sweat is secreted by the sweat gland tube, the chloride is not normally reabsorbed, so the chloride concentration in the sweat is significantly increased, determination The chloride concentration of sweat is normal at 7 to 49 mmol/L. If it reaches 60 mmol/L, the diagnosis can be confirmed. The normal sodium concentration is 22 mmol/L, and the average child is 103 mmol/L.

Treatment mainly uses pancreatic enzymes orally, including pancreatic lipase, amylase and protease. The diet should take high protein, high heat and low fat diet.

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