The peak age of lactose intolerance is different in different countries. Japanese children are 7-8 years old and African children are 3-5 years old. A survey of 65,438+068 healthy children aged 3-65 and 438 in four cities in China shows that the incidence of lactase deficiency is high, and 87% of children are lactose intolerant at 7-8 years old.
The sugar in breast milk and milk is mainly lactose. If the secretion of lactase on the surface of small intestine, especially at the top of jejunum mucosa villi, is reduced or its activity is not high, the lactose in milk can not be completely digested and decomposed, and some lactose is fermented into lactic acid, hydrogen, methane and carbon dioxide by colon flora. Lactic acid can increase intestinal peristalsis and diarrhea. Carbon dioxide produces flatulence in the intestine, increases intestinal peristalsis, makes children feel uneasy, and may occasionally induce intestinal spasm and colic. The increase of lactic acid also decreased the pH value of feces.
Basic introduction nickname: Lactase lack of English name: Lactase intake clinic: pediatric multi-population: children aged 7-8 Common reasons: low lactase secretion, lactose in breast milk can not be completely digested and decomposed. Common symptoms: diarrhea, from several times a day to more than 10. The etiology, clinical manifestations, diagnosis, differential diagnosis, treatment, prognosis and causes of lactose intolerance are generally divided into three types: congenital lactase deficiency, secondary lactase deficiency and adult lactase deficiency. 1. Congenital lactase deficiency is caused by congenital lactase deficiency or insufficient activity. The incidence is related to race and heredity, and it belongs to autosomal recessive inheritance. Lactose intolerance of newborns in China mostly falls into this category. Because the amount and activity of enzyme deficiency vary from person to person, the symptoms are different. 2. Secondary lactase deficiency mostly occurs after enteritis, and enzyme deficiency occurs when the top of intestinal villi is damaged, but lactose intolerance diarrhea occurs after enteritis, which generally takes 0.5 ~ 2 months until the bottom of villi grows to the top, and enough lactase can be secreted. Many newborns and premature infants are temporarily low in lactase activity due to immature intestinal mucosa development in neonatal period, temporarily intolerant of lactose, and have more defecation times, which will decrease after normal activities. Lactase deficiency is the most common in adults, which is related to the genetic changes caused by the eating habits of human generations. The results showed that lactase activity gradually decreased with age until it disappeared, causing lactose intolerance or lactose malabsorption. There are racial and regional differences in onset age and incidence. The onset age of Asians is 7-8 years old, and some ethnic groups in Europe and America are about 20 years old. The incidence of yellow race and black race is higher than that of white race. The main clinical symptom is diarrhea several times a day to more than 10 times. Most children have a lot of intestinal gas and often bring out a small amount of feces on diapers. Most of the stools are yellow or turquoise thin paste stools, or egg drop soup, with many bubbles and milk lumps, and a few children have milk return or vomiting. Children will also be accompanied by abdominal distension and anxiety in different degrees, and they are prone to crying, and defecation or diarrhea will be improved after treatment. Colic is rare and often occurs in the course of disease, but it can also occur before diarrhea. In severe cases, dehydration, acidosis and growth retardation occur. Can occur, and most of them have no fever. Children diagnosed with lactose intolerance are mainly diarrhea, which may be accompanied by crying, vomiting and occasionally colic. Routine stool examination is negative, reducing sugar is positive, and low pH value indicates lactose intolerance. It has a good therapeutic effect on lactose-free formula milk, and diarrhea occurs again after switching to ordinary formula milk or breastfeeding. According to the above situation, it can be determined that the child has lactose intolerance. Differential diagnosis 1. Enteritis is caused by rotavirus or bacterial infection, with acute onset and severe symptoms, often accompanied by fever, mucus in stool, and possibly purulent blood. Under the stool microscope, pus cells and red blood cells can be seen. Diarrhea caused by lactose intolerance has a slow onset, no fever, mushy stool, negative microscopic examination and positive reducing sugar. 2. Milk protein allergy, especially light milk protein allergy. When children with this disease switch to breast milk, diarrhea stops, while children with lactose intolerance are intolerant of breast milk and milk. It is worth noting that milk allergy may coexist with lactose intolerance, so it is still not enough to switch to breast milk diarrhea. However, the stool reducing sugar test of children with milk protein allergy is negative, which is helpful to distinguish the two. 3. Infantile colic syndrome often occurs in infants within 3 months, with unknown causes and long colic time, and recurs within 3 months. But the reducing sugar in the stool is negative. If children with lactose intolerance defecate less frequently, it will not affect their growth and development and does not need special treatment. If you have frequent diarrhea and slow weight gain, you need to adjust your diet. If the acute phase is accompanied by dehydration, fluid should be supplemented intravenously or orally to correct dehydration. Lactose-free formula (including milk-based or soybean-based lactose-free formula) can be used first. After diarrhea stops, the number of breast-feeding can be gradually increased according to the child's tolerance, and breast milk and lactose-free formula can be mixed. Unlike milk protein allergy, the symptoms of lactose intolerance are directly proportional to the amount of lactose ingested, so it is rarely necessary to completely remove lactose from the diet. However, milk protein allergy is dose-independent, and even a small amount of antigen can cause typical symptoms. Selection of alternative food and matters needing attention: 1. Lactose-free formula milk or fresh milk is a kind of formula milk powder without lactose. Maltose or dextran is used instead of lactose in the ingredients of infant formula milk, and protein, fat and other ingredients are still retained in the ingredients of formula milk. Lactose-free fresh milk is to add lactase to the fresh milk before drinking, digest and decompose the lactose in the fresh milk, and then drink. 2. Soymilk is a special formula milk made from soybeans, and it does not contain lactose. In protein, soybean protein is the main ingredient, and methionine and taurine are added. Although this formula of soybean milk is different from soybean milk and soybean powder that have not been specially made, it is more suitable for the growth and development of infants, but it is not suitable for long-term use. Children who have cereal or wheat food for 3.3 months can add cereal or wheat food, which is effective for mild diarrhea. 4. Yogurt Yogurt made by adding lactic acid bacteria to fresh milk, some lactose has been decomposed into lactic acid, becoming a lactose-free product. Yogurt can be stored at 0 ~ 10℃ for no more than 14 days. You don't have to heat it when you drink it. For children who are not used to cold drinks, you can heat it a little. There should be no bubbles and yeast smell in the non-deteriorating yogurt, and there should be no mold or mildew on the surface. In addition, lactic acid bacteria milk powder is made of milk by adding water, and then put in warm water (40℃) for 4 ~ 6 hours to become yogurt. No matter what kind of food is used to replace the prognosis, the general principle is that children's nutritional needs cannot be reduced. When they can increase complementary food, diarrhea will gradually stop after reducing breast milk or milk, and the prognosis is good.