A positive stool carbohydrate test shows that not all carbohydrates are utilized in the digestive tract. This may be due to a lack of enzymes that break them down in the small intestine, or a violation of the composition of the microflora that absorbs carbohydrates in the large intestine. As the only source of nutrition for infants is milk, the condition of lactose intolerance attracts the most attention in infants under one year of age.
Carbohydrates, along with proteins and fats, are the main components of food. They enter the digestive tract in the composition of products mainly of plant origin: fruits, vegetables, cereals, products containing flour, such as bread, pastries, pasta. For breastfed babies, milk lactose is the main carbohydrate. Artificial mixtures made on the basis of milk contain, in addition to lactose,sucrose as a sweetener.
Reducing sugars - lactose, m altose, glucose - are determined by chemical analysis for carbohydrates in feces.
When is a study ordered?
Typical examination does not include analysis of feces for carbohydrates. It is carried out only when symptoms of intolerance to lactose, sucrose, glucose, galactose appear. Lactose intolerance is much more common than other types of intolerance.
Lactose intolerance
Lactose, or milk sugar, is the main carbohydrate in milk. It is a disaccharide formed by residues of glucose and galactose. Lactose represents 90% of all milk carbohydrates.
Milk lactose, once in the small intestine, is broken down by the enzyme lactase to glucose and galactose. Lactase is the only enzyme in the body that acts on milk sugar. It is produced by cells in the small intestine. Unsplit milk sugar moves further into the large intestine, where it is used by microflora, mainly lactobacilli. Thus, when analyzing feces for carbohydrates in a child older than a year, lactose should not be detected.
In some cases, lactose is not broken down in the small intestine. If the lactase enzyme is not active enough or its quantity is not enough to break down the incoming lactose, they speak of lactase deficiency. If the insufficiency is minor, no symptoms occur. If lactase does not break down a lot of lactose, the disaccharide enters the large intestine in excess, is detected when analyzing feces forcarbohydrates, causes characteristic symptoms. This condition is called lactose intolerance. It can also be caused by other causes, such as a decrease in the absorption of glucose and galactose in the intestine.
Causes of lactose intolerance in children
Reduced lactase activity is noted in 2/3 of children born. In most cases, this does not lead to the appearance of the disease. By 2-3 months of life, the enzyme begins to work in full force.
In full-term babies under one year old, in the predominant number of cases, lactose intolerance is caused by overfeeding, immaturity of the intestine and (or) its pathologies. In premature babies, low lactase activity is detected in almost everyone. Most often, it is in these cases that the doctor recommends taking a stool analysis for carbohydrates.
Lactose intolerance during overfeeding is due to an excess of milk sugar in the intestines of the child. Although the amount and activity of the enzyme is normal, they are not enough to break down the carbohydrate supplied with excess milk. Undigested lactose is transported in large quantities to the large intestine, resulting in diarrhea and other symptoms. Most often, this condition occurs when feeding "on demand". Lactose overload is of particular importance in the development of symptoms in infants born prematurely or who have undergone hypoxia during labor. Dr. Komarovsky considers overfeeding the main reason for the diagnosis of lactose intolerance and the appointment of a fecal analysis for carbohydrate content.
In children born at 28-30 weeks of gestation, the small intestine has not matured morphologically andfunctionally. Gradually, the intestine matures and the activity of the enzyme returns to normal.
Acquired (secondary) lactose intolerance is quite common. Its causes are most often acute intestinal infections: rotavirus, salmonellosis or the use of antibiotics and other drugs (anabolic steroids).
Signs of lactose, sucrose and monosaccharide intolerance
Shortly after taking milk, there is discomfort, a feeling of bloating, rumbling in the stomach, the stool sometimes liquefies. In infants, the stools are usually watery, sour, yellow, frothy with a lot of gas. The main symptom is diarrhea, although with a slight hypolactasia, flatulence and intestinal colic may first appear. In infants, due to an increase in intra-abdominal pressure, frequent regurgitation is observed. Appetite is maintained, weight is added slowly.
Advantages and disadvantages of the method
The analysis of feces for carbohydrates is widely used due to its low cost and ease of implementation. However, it has disadvantages:
- In infants, the microflora of the large intestine is only populated, so lactose is not utilized in the large intestine and more of it enters the feces, sometimes the content exceeds 1%.
- The method does not allow to determine the content of individual carbohydrates: lactose, sucrose or glucose for the purpose of differential diagnosis of lactase, sucrose or other types of deficiency. It should be noted that lactase deficiencyis much more common than other species.
Analysis
Determination of carbohydrates in feces is carried out by the Benedict reaction or using test strips. There are several reactions for determining reducing sugars, which include lactose: the Trommer, Felling and Benedict reactions and others. They are based on the ability of some sugars in an alkaline medium to reduce metals in the composition of the s alt, which leads to a change in the color of the solution. The reaction with Benedict's reagent is the most sensitive, that is, it allows you to detect very low carbohydrate content in the material sample.
An equal amount of Benedict's reagent is added to several drops of stool centrifugate. The test tube is placed for several minutes in a water bath, after cooling, the result is evaluated.
Analysis results
Benedict's reagent contains copper sulfate, the solution of which is blue. If there are no sugars in the feces, the reaction does not go on, the mixture remains blue. If the stool contains lactose, it oxidizes the copper ion to red-brick copper oxide (I). A small amount of carbohydrates will form a small amount of reddish oxide, which will mix with the blue color of the sulfate, resulting in a green color. A significant presence of carbohydrates gives the mixture a red color. The laboratory assistant compares the resulting color with the colors of standard solutions. According to the table, it determines what carbohydrate content a given color corresponds to. The result is given in % or g/l.
Interpretation of analysis results
Deciphering the analysis of feces for carbohydrates in infants:
- up to 2 weeks - no more than 1%,
- from 2 weeks to 6 months - 0.5-0.6%,
- from 6 months to a year - 0-0, 25%,
- older than a year - 0%.
For newborns up to 2 weeks of age, the result of 1% and below is good, it indicates the formation of the microflora of the large intestine. A result greater than 1% is considered a deviation and requires a careful approach. Most likely, the analysis will need to be retaken.
For a breastfed or formula-fed baby from 2 weeks of age to 6 months, a good indicator is below 0.5-0.6%, indicating the absence of lactase deficiency. If the result is higher, lactase deficiency is possible. In children of this age, an increased content of carbohydrates in the feces is often noted, which most often indicates the immaturity of the digestive tract. But even the detection of lactase deficiency should not become a reason for not breastfeeding. Since this condition is well treated while maintaining natural feeding with drugs containing enzymes.
Children over one year old should have a 0% result. If it is higher, incomplete lactose utilization may be suspected. Most likely, the cause is the pathology of the intestinal tract or dysbacteriosis.
Children over 3-5 years old and adults should have a 0% result. An increased result indicates, most often, adult-type lactose intolerance, which occurs in 70% of the world's population.
Exceeding the norm is not the basis for a diagnosis. Other studies are also needed. Therefore, the decoding of the analysis of feces for carbohydrates should be led by a doctor.
Additional Research
To make a diagnosis of "lactase deficiency", the doctor takes into account, first of all, the clinical picture. Moreover, one or two manifestations of pathology are few. All clinical signs of deficiency must be present. Important information may be the presence of a similar pathology in the family, the disappearance of diarrhea when replacing milk with a dairy-free formula.
The diagnosis is confirmed by additional laboratory tests:
- fecal pH less than 5.5;
- positive analysis of the baby's feces for carbohydrates;
- no increase in blood glucose concentration after lactose load.
The most informative test is the quantitative determination of lactase activity in a biopath of the small intestine mucosa. But this is a painful, difficult, and expensive test, so it's usually not prescribed.
