Urine tests allow you to quickly and effectively identify a variety of diseases, not only the urinary system. In children, this method of research is used especially often – after all, a small child is unable to tell about his feelings or to clearly answer the doctor’s questions.
Urine is formed in the kidneys from blood plasma. The main processes occur in the nephron – a coil of thin capillaries. In it, through filtration, the so-called primary urine is formed.
The process of formation of the final urine occurs in the renal tubules. At this stage, vital substances (vitamins, amino acids, electrolytes, etc.) from the urine are absorbed back into the blood, and the end products of metabolism and xenobiotics, which are foreign to our body chemicals that we get from food, are removed from the blood. These are components that must be removed (bilirubin, urea, etc.).
Further, through the system of collecting tubules, urine enters the renal pelvis, then into the ureter, then accumulates in the bladder, and from there it is brought out. The composition of urine is influenced by all processes on this long path of transformation.
If the mechanism fails at least in one area, it can get substances that normally should not be (or their number should be small).
When interpreting it is important to consider the features of the anatomical structure of children. So, in newborns, nephrons are structurally and functionally still immature. The concentration ability of the kidneys is also reduced, so the urine in babies of the first year of life has a low relative density.
The permeability of the vessels of the nephrons themselves at this age is also increased, and glucose, proteins, and even formed elements of the blood (erythrocytes and leukocytes) appear in children’s urine with a greater frequency than in adults.
However, in children older than a year, the presence of such components is no longer the norm. However, the formation of the urinary system does not occur immediately.
For this very reason, in children of the first 2–3 years of life, the filtration mechanisms of blood plasma are poorly adjusted, and the test results often require clarification and rechecking.
- Collect urine in special containers that are sold in pharmacies. Food glass containers are not suitable for this purpose.
- For general analysis, 50–100 ml of urine is required, for urine analysis according to Nechyporenko – at least 10 ml.
- For most non-quantitative methods, which include general urine analysis, an average portion of urine is used, collected during urination at any time of the day. The first morning portion is the most concentrated, so it is easier to identify substances present in the blood in minimal quantities. It is advisable to collect it in the event that it is necessary to check all the indicators of the total urine analysis to a single.
- Urine for general analysis should be delivered to the laboratory within 1 hour, and the study should be conducted while the material under study is still warm. In all other cases, the urine is stored in a glass container in a cool place, for example in the refrigerator.
- Before taking urine, it is necessary to thoroughly clean the external genitalia in both girls and boys.
To identify various ailments, there are several types of urinary diagnostics, among which the general urinalysis is the most common. This study includes an assessment of the physicochemical characteristics of urine and sediment microscopy.
The results of the general analysis of urine are considered very informative: according to them the doctor can judge the work of the organs of the urinary system, heart, liver, pancreas, gastrointestinal tract and pituitary.
Color Fresh urine in a healthy child has a straw yellow color, as it is colored with urochrome pigment. With various diseases are possible options. Pale color is observed with diabetes mellitus, dark yellow – with hepatitis and obstructive jaundice, red – with hematuria and hemoglobinuria.
Sometimes the color changes due to food. So, carrot and beet pigments can paint urine in a reddish color, and rhubarb and tarragon give a greenish tint.
Transparency Normal urine is clear. It can dim if it contains a lot of salts, cellular elements, bacteria, mucus and fat droplets.
The same thing will happen if the urine settles for a long time: urates, uric acid salts, will fall out. But it will not affect the results.
Odor Fresh urine has an unsharp peculiar odor, and if it stays in the air for a long time, ammonia spirit appears due to microbial fermentation. Ammonia odor during urination may indicate severe forms of cystitis, fecal indicates the presence of cystic and rectal fistula.
With diabetes, the smell of urine gets apple notes. At the same time, this indicator is only indicative for diagnosis.
Density A healthy child has a daily urine density ranging from 1006 to 1025 g / l. This indicator depends mainly on the concentration of urea: the more urine, the lower its density, and vice versa. High density can be observed with kidney damage or impaired nitrogen function.
Although the habit of drinking too little liquid leads to the same values. Low density is possible with abundant drinking, with various diseases of the kidneys or reducing their concentration function, as well as with diabetes insipidus.
pH Normally, a weak acid reaction is recorded in fresh urine. For all ages, a value in the range of 5–7 units is considered satisfactory.
Only in newborns, the urine is more acidic: their pH varies in the range of 5.4–5.9. If deviations from the extreme limits are kept for a long time, this is a favorable factor for the precipitation of salts. Alkaline urine is characteristic of bacterial inflammation, kidney bleeding and a vegetarian diet.
The acidic environment is established during fever, diabetes, fasting or eating large amounts of protein foods, as well as after exercise.
Ascorbic acid About pathologically acid reaction of urine allows to judge the detection of ascorbic acid in a concentration of more than 2 mmol / l. Normally, young children are allocated 10−80 mg of vitamin C per day.
His absence is an indirect sign of his lack.
Protein In healthy children, urine is practically free of protein. Normally, its minimum amount is so insignificant that the general analysis simply does not reveal it. If protein is found, it is either evidence of kidney and urinary tract diseases, or a sign of fever, excessive exercise, or hypothermia.
For accurate diagnosis requires careful examination.
Glucose In the urine of a healthy child, it is contained in the form of traces (up to 0.002%) and is not detected during routine urinalysis. The amount of glucose increases in the event that carbohydrates do not have time to digest the body.
Its presence in the urine suggests diabetes, hyperthyroidism, pheochromocytoma, brain concussion and other pathological conditions.
Acetone (ketone bodies) These substances are the products of the oxidation of fats and proteins. Normally, they are detected in very small quantities.
A high content of acetone is characteristic of severe forms of diabetes mellitus, although it is observed during repeated vomiting and after general anesthesia. In any case, abnormalities require medical assistance.
Bile pigments (bilirubin) and bile acids. In the urine of healthy children, they are contained in minimal quantities.
In the opposite case we are talking about liver damage.
Urobilinogen This is a substance derived from bilirubin in the intestines and re-entering the liver is completely destroyed. Urobilin samples normally give a negative or weakly positive response.
Its quantity increases with hepatitis of various genesis, hemolytic anemia.
Sterobilinogen Unlike urobilinogen, this component is a common ingredient in urine, the daily elimination of which is 0-6 mg.
Erythrocytes Normally, they can be no more than 3 in sight. Detection of altered erythrocytes indicates their renal origin. Then doctors think of polycystic kidney disease, nephritis and tumors.
Unchanged red blood cells enter the urine from the urinary tract, so they talk about infection in this zone.
Leukocytes Single white blood cells can be found in the urine of healthy children, especially in girls. If more than 3−5 pieces are in sight, this is a deviation from the norm.
The presence of a large number of leukocytes is characteristic of cystitis, urethritis, balanoposthitis.
Bacteria In healthy children, urine is sterile. However, the presence of a small amount of bacteria in the urine does not have a diagnostic value.
An indicative criterion is the content of 105 or more microbes in 1 ml of urine.
Epithelial cells Deformed epithelial cells of the mucous membrane of the urinary tract indicate inflammation or trauma (the latter can cause stones in the urinary tract). The presence of a small number of them does not matter.
Cylinders These are small cylindrical elements made up of protein or cells that can precipitate. Normally, they are not detected.
Only hyaline cylinders can be found in single quantities. In all other cases, we can talk about heavy lesions of the kidneys and urinary tract.
Mucus Mucus in the urine appears in inflammatory diseases of the lower urinary tract – urethritis, cystitis, vulva, balanoposthitis.
Fat Present in the sediment with nephrotic syndrome, diabetes. Normally not detected.
Yeast fungi They are found in the urine in large quantities after the use of antibiotics, which in fact is an undesirable complication of therapy. In this case, the question of the abolition of antibiotics.
Inorganic sediment The presence of salts in the urine sediment has no diagnostic value and depends on the urine pH. Uric acid, urate, calcium oxalate, calcium carbonate fall out in the urine, which is acidic. The triple phosphates, phosphates, neutral phosphate lime are precipitated in alkaline medium.
The appearance in the urine of calcium oxalate, oxalate crystals, sometimes in large quantities, is usually associated with the consumption of foods with their high content. Phosphates and tripelphosphates are characteristic of cystitis.
Leucine and tyrosine are found with severe liver damage, hematoidin – with bleeding in the urinary tract or with prolonged retention of blood in the bladder. Cholesterol appears in the urine during cell breakdown.
Cystine deposits are found in cystinuria, a rare hereditary disease associated with impaired protein metabolism.
Quantitative analyzes of urine In addition to the general analysis of urine, there are more accurate methods for determining the formed elements of the blood, that is, leukocytes and erythrocytes. Doctors usually resort to such studies when an inflammatory process in the urinary system is suspected. The most informative among them are urine tests according to Amburz and Addis-Kakovsky.
All urine is collected in one container, only in the first case in 3–4 hours, and in the second – in 12 or 24. Next, it calculates how many leukocytes and erythrocytes the body excreted over a given period of time.
For example, it is known that normally no more than 1 million erythrocytes and no more than 2 million leukocytes can be excreted with urine per day. From these figures and laboratory technicians repel.
A simpler, though less accurate method, which is most often used in children, is the Nechiporenko sampling technique. For the study, an average portion of urine is taken, then the number of blood elements per 1 ml of urine is counted, without regard to time.
Special samples Some characteristics that can be studied in urine are not included in the general analysis, so they have to be ordered separately. The indicators will have a long list, but as an example you can take a sample for alpha-amylase. The presence of this substance allows to assess the state of the pancreas.
Another study, the Sulkovich test, is used to detect calcium salts in the urine in case of suspected overdose of vitamin D3. Such analyzes are collected according to different schemes, depending on the goal pursued.
Daily urine The most common method of this large-scale urodiagnosis is the Zimnitsky test. Its essence is to determine the amount and relative density of urine excreted every 3 hours during the day. The method allows to assess the ability of the kidneys to concentrate and dilute urine.
Additionally, you can determine the amount of isolated protein and glucose, calculate the erythrocytes. The analysis is time consuming and requires patience from parents.
The night before, you will have to prepare 8 clean bottles and number them each. The first morning urine (at 6-7 in the morning) should be drained.
Starting at 9 am, the child urinates every 3 hours in a separate bottle. At night he will have to wake up.
At 6 or 7 o’clock (depending on when the collection began) the next morning, the last dose is collected and all 8 servings are sent to the laboratory, where the relative density of each of them is determined, the night and day diuresis is measured (the amount allocated per day and night urine), and if necessary – the amount of protein in each tank. A prerequisite for correctly assessing the function of the kidneys with the help of this sample is compliance with the usual water regime.
It is very important to fix the amount of liquid drunk by the baby during the day.
There are other types of daily analysis. Thus, according to the prescription of a doctor, biochemical studies of daily urine on sodium, potassium, phosphorus, calcium, urea, creatinine, lead, hormones and other indicators are carried out.
Results are compared with reference data. All daily urine tests, except for the Zimnitsky sample, are collected according to the same scheme.
At any convenient time (usually it is 9 am) the bladder is completely empty and this first portion is drained. All urine is collected in the container, which will be allocated thereafter in the next day. At 9:00 am the next day, the bladder is completely empty again and the last portion of urine is added to the container.
Then they calculate and record the total amount of urine isolated during all this time, shake them carefully, pour 80-100 ml into a separate jar and send this volume to the laboratory. If by mistake at least one of the portions was not collected, you need to start all over again.
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