Lactase insufficiency in children

Lactase insufficiency is a disease that provokes the emergence of malabsorption syndrome (watery diarrhea) and is caused by a breakdown in the breakdown of lactose in the small intestine.

Primary lactase deficiency is a decrease in lactase activity with a preserved enterocyte. The primary lactase deficiency includes congenital lactase insufficiency, adult lactase deficiency and transient lactase deficiency of premature infants.

Secondary lactase deficiency is a decrease in lactase activity associated with damage to the enterocyte. Damage to the enterocyte is possible with an infectious or allergic (for example, sensitization to cow's milk proteins) inflammatory process in the intestine, as well as a decrease in the pool of enterocytes due to a decrease in the area of the intestinal mucosa due to atrophy of the villi, reducing the length of the jejunum after resection or with a short-term congenital syndrome guts.

Congenital alaktasia is a rare disease provoked by a mutation outside the LCT gene , which codes for the synthesis of lactase. In Finland, the cases of this disease are described, called "recessive diseases of the Finnish type". Transient lactase deficiency of prematurity is associated with low activity of the enzyme in children born before the 34-36th week of gestation.

Secondary lactase insufficiency often occurs in infants on the background of infectious, allergic diseases as a component of post-resection syndrome with a number of abnormalities of intestinal development. Lactase of the brush border in comparison with other disaccharidases is located closer to the top of the villi, especially in the duodenum, which is responsible for the frequency of lactase deficiency compared to the deficiency of other enzymes in damage to the mucous membrane of any etiology.

ICD-10 codes

• E73.0. Congenital insufficiency of lactase.
• E73.1. Secondary lactase deficiency.
• E73.8. Other types of lactose intolerance.

Symptoms of lactase deficiency

Entering the undigested lactose into the large intestine causes flatulence and swelling of the intestine due to the formation of a large number of gases during fermentation. In young children, flatulence can cause regurgitation, but this is not enough for isolated lactase deficiency. When the amount of lactose delivered exceeds the utilization capacity of bacteria, osmotic diarrhea develops. Characterized by overcooked stools of yellow color with a sour smell, liquefied, frothy. Pathological impurities are absent. At primary lactase deficiency, the severity of clinical symptoms clearly correlates with the dose of lactose consumed. The severity of the clinical picture increases with the increase in the amount of milk consumed. Characteristic anxiety a few minutes after the start of feeding while maintaining a good appetite. A different situation occurs when the amount of lactic microflora decreases. In this case, the compensatory possibilities of the microflora utilizing lactose are reduced, diarrhea occurs with smaller amounts of undigested lactose, the pH in the intestine is shifted to the alkaline side, which aggravates the dysbacteriosis. This situation is typical for the combination of primary lactase deficiency with intestinal dysbacteriosis or secondary lactase deficiency and intestinal infection. In these cases, the stool can have pathological impurities (mucus, greens). With diarrhea, the development of excoxicosis, hypotrophy, especially with congenital alaktasia. The emergence of acidosis, persistent vomiting, aminoaciduria for isolated primary lactase insufficiency is uncharacteristic, this symptomatology requires differential diagnosis with hereditary metabolic and other diseases.

Diagnosis of lactase deficiency

The diagnosis of lactase deficiency is based on the assessment of the clinical picture, diet during the manifestation of the disease (whether the child received lactose with food), the search for factors leading to secondary lactase deficiency. Deviations from the norm of the results of the studies listed below without clinical symptoms do not require therapeutic measures.

• Determining the carbohydrate content in the feces reflects the overall ability to assimilate carbohydrates. The method does not allow differentiating different types of disaccharidase deficiency among themselves, but together with clinical data is sufficient for screening and controlling the correctness of diet selection. In infancy, the carbohydrate content in stool should not exceed 0.25%. In children older than 1 year, this sample should be negative.
• Determining the content of hydrogen, methane or labeled with ¹¹ C C0 ₂ in the exhaled air. Methods reflect the activity of microflora on the fermentation of lactose. It is advisable to determine the concentration of gases after the dosed load is normal or labeled with lactose. Diagnostic criterion in adults and children of older age is the increase in hydrogen in the exhaled air after a load of 20 lactose (particles per million) lactose.
• Load tests with lactose determine the glycemia, recorded before and after loading with lactose in a dose of 2 g / kg of body weight. When lactase deficiency occurs flat or flattened type of glycemic curve (normal glycemia increase is more than 1,1 mmol / l). Load tests with lactose are unsuitable for the diagnosis of lactase deficiency in situations where it is possible to assume impairment of absorption and damage to the intestinal mucosa.

• The procedure for determining the activity of lactase in biopsies or washings from the mucous membrane of the small intestine lacks the drawbacks of the previous methods. This method is considered the "gold standard" for diagnosing lactase deficiency, but the invasiveness of the method limits its use.
• Molecular genetic diagnosis based on the detection of the mutation of the intron gene has been developed for lactase deficiency of the "adult type". The test is considered economically feasible, carried out once, which is more convenient for the patient than load tests. In children under 12, the method can be used only to exclude lactase deficiency. Differential diagnosis is carried out with watery diarrhea of another etiology.

Treatment of lactase deficiency

The treatment of lactase deficiency is based on diet therapy - limiting the consumption of lactose, the degree of reduction is selected taking into account the excretion of carbohydrates with feces. In diseases leading to secondary lactase deficiency, the main attention should be paid to the treatment of the underlying disease. Reducing the amount of lactose in the diet is a temporary measure necessary to restore the mucosa of the small intestine.

In children of early age, the most rational tactic is considered the tactic of an individual step-by-step selection of the amount of lactose in a diet. Do not completely exclude lactose from the baby's nutrition, even if a lactase deficiency is found, since lactose serves as a prebiotic and a source of galactose. If the child is on natural feeding, the best way to reduce the consumption of lactose is considered to be the use of lactase preparations, mixed with expressed breast milk. For children under 1 year, the use of the food supplement "Lactase Baby" is allowed. The drug is given at each feeding (770-800 mg of lactase or 1 capsule of "Lactase Baby" for every 100 ml of milk), starting with a portion of expressed milk with lactase, and then the baby is fed from the breast.

Children who are on artificial or mixed feeding should choose food with the maximum amount of lactose, which does not cause digestion and increase the carbohydrate in the feces. Individual selection of the diet is carried out by combining the de-lactose product and the standard adapted mixture in a ratio of 2: 1, 1: 1 or 1: 2. In the absence of allergy to cow's milk proteins, lactose-free adapted milk mixtures are used, in the presence of allergies - mixtures based on deep protein hydrolyzate. With a pronounced deficiency of lactase, inefficacy of reducing the amount of lactose in half, low-lactose or lactose-free products are used as monotherapy. With secondary lactase deficiency against a background of food allergy, correction of the diet should begin with lactose-free mixtures based on the complete protein hydrolyzate. Mixtures based on soy protein are not considered drugs of choice for dietary therapy of lactase deficiency.

Prevention of celiac disease in children is in the late (after 8 months of life) introduction of manna and oatmeal in the diet, prevention of exacerbations - in the long-term adherence to the agliadin diet.

Clinical follow-up is carried out for life. Correct the diet and substitution therapy, monitor the dynamics of growth and body weight, evaluate the coprogram, hold a massage, exercise therapy.

[1], [2], [3], [4], [5], [6], [7]