renal clearance. Calculation methods for determining the value of KF

The renal clearance of any substance B is equal to the ratio of the rate of excretion of this substance in the urine to its concentration in the blood plasma:

C in = ---------- (ml / min), (1)

where Cv - clearance, Mv and Pv - content in urine (M) and plasma (P) of blood, respectively, V - the volume of urine formed in 1 min.

By a simple transformation of equation (1), we obtain Sv x Pv = Mv x V (amount of substance / time) (2)

It can be seen from this that the formula for calculating the clearance was derived on the basis of equalizing the amount of a substance removed from the blood plasma per unit time (St. Pv) and the amount of a substance excreted in the urine during the same time (Mv. V). In other words, renal clearance reflects the rate of plasma clearance from a particular substance. This indicator is measured in ml/min, and therefore it can be considered as the "volumetric clearance rate" of the plasma from a certain substance.

Thus, the clearance of any substance is quantitatively equal to the volume of plasma that completely clears this substance from the kidneys in 1 min.

This definition is quite convenient for describing equation (1), but it accurately reflects the actual state of affairs in only two cases. The fact is that usually there is no complete purification of any part of the renal blood flow; on the contrary, there is a partial purification of all blood passing through the kidneys. At the same time, there are two substances from which a certain volume of plasma is actually completely cleared. These two exceptions are of particular relevance to the uropoiesis hypothesis and serve as the basis for the overall evaluation of renal function.

1. Clearance of inulin corresponds to the glomerular filtration rate, i.e. part of the total renal plasma flow filtered into the urinary tubules.

2. The clearance of para-aminohyppuric acid (PAH) almost reaches the maximum possible value, i.e. almost equal to the total renal plasma flow.

Homeostatic functions of the kidneys

The kidneys are involved in the regulation of:

1. The volume of blood and other fluids of the internal environment.

2. Constancy of osmotic pressure of blood, plasma, lymph and other body fluids.

3. The ionic composition of the liquids of the internal environment and the ionic balance of the body (Na + , K + , Cl _ , P _ , Ca +).

4. In maintaining acid-base balance.

5. Excretion of excess organic substances supplied with food or formed during metabolism (glucose, amino acids).

6. Excretion of end products of nitrogen metabolism and foreign substances.

7. In maintaining blood pressure (renin-angiotensin-aldosterone system).

8. Secretion of enzymes and physiologically active substances (renin, bradykinin, prostaglandins, urokinase, vitamin D 3).

9. Participate in the regulation of erythropoiesis (erythropoietin).

10 In the kidneys synthesized - urokinase, which is involved in fibrinolysis.

Thus, the kidneys are an organ involved in ensuring the constancy of the main physico-chemical constants of blood and other fluids of the internal environment of the body, circulatory homeostasis, and regulation of the metabolism of various organic substances.

CLEARANCE in medicine(English) clearance) - the rate of purification of blood plasma, other media or tissues of the body from any substance in the process of its biotransformation, redistribution in the body and (or) excretion from the body.

The concept of "clearance" in medicine was formulated in 1929 by D. D. Van Slyke et al. in relation only to the purification of plasma from substances excreted by the kidneys, in particular from urea. At the same time, K. was defined as the degree of purification from any substance of the blood plasma that passed through the kidneys in 1 minute. In subsequent years, due to the widespread use of indicator dyes and radioactive isotopes in diagnostics, the concept of "clearance" began to be used to denote not only the plasma purification indicator, but also the rate of decrease of the indicator substance from the studied volume of any tissue or organ. However, the traditional use of the term "clearance" (as applied to plasma clearance) is the most stable.

In the current terminology, the purification of plasma from any substance is referred to as K. of this substance, for example. K. inulin, K. creatinine. In the formulas, K. is denoted by the symbol C, next to the Crimea, the substance is abbreviated, for example. Cin - K. inulin. Depending on the role of which organ in plasma purification is being studied, they speak of renal K., hepatic K., etc. There is also the concept of general, or total plasma K. (Str), the value of which characterizes the rate of plasma purification from substances, regardless of the mechanisms of purification (excretion by excretory organs, biotransformation with loss of original properties, etc.). Having simultaneously determined the total plasma K. and the intensity of purification from this substance by the kidney or liver, the role of these organs in the total plasma K. was shown. liver in K. bromsulfofthalein and Bengal rose.

To determine the total plasma K., the indicator substance is injected into a vein once and several blood samples are collected at certain time intervals to study the dynamics of the concentration of the injected substance in the plasma. Decreased blood levels of certain substances, e.g. PAG occurs exponentially (for equal time intervals the concentration decreases by the same relative part of the initial value), other substances, for example, bromosulfophthalein, ethanol, cytembene, in the form of a linear dependence (the concentration decreases by the same absolute value for equal time intervals), and some substances have a curve of decreasing concentration in the blood in the form of an incorrect function. Depending on the nature of the drop in the concentration of a substance in the blood plasma, various formulas are used to calculate K.

Total plasma K. is calculated by the formula

where I is the amount of the substance introduced into the blood, S is the area under the plasma concentration curve (along the ordinate) during the study (on the abscissa). With the exponential nature of the concentration curve, in order not to determine the area under it, use the formula

Ctr \u003d I * 0.693 / P 0 T 1/2

where P 0 is the initial plasma concentration in mg / ml, T 1/2 is the time (in minutes or hours) for reducing the concentration of a substance in plasma by 2 times, I is the amount of the administered substance.

The role of individual organs in K. of any substance can be established by the difference in the concentration of this substance in the plasma of the blood flowing to the organ and flowing from it. This difference can also be judged by the difference in the concentrations of the substance in the plasma and in excreted fluids (for excretory organs). K. substances, due to the excretory function, is determined by the general formula

where V is the volume of secretion (excretion) obtained per unit of time (usually in ml / min), K is the concentration of the substance, i.e. the amount in 1 ml of secretion (for example, urine, bile), P is the concentration of the substance in plasma . It is methodically essential that to determine the total plasma K. produce a single injection of the substance; for measurement of organ, in particular renal, K. continuous infusion is preferable in order to maintain the concentration of the test substance in plasma at a constant level.

Clinical significance of clearance tests

The most widely used and developed clearance tests have been in the study of renal functions. With the help of clearance tests, the renal plasma flow, glomerular filtration, reabsorption and secretion are determined (see Kidneys). At the same time differences in renal K. of different substances are used. The definition of renal plasma flow is based on the measurement of K. cardiotrast, PAG, or hippuron, from which the blood plasma is completely cleared with a single passage through the cortical substance of the kidney. To measure glomerular filtration, K. is determined for substances that are filtered but not secreted or reabsorbed (inulin, sodium thiosulfate, polyethylene glycol 1000, mannitol). The result obtained leads to a standard body surface (1.73 m 2). K. inulin in humans is 127, and the clearance of PAG is 624 ml / min per 1.73 m 2. Since long-term infusion into the vein of solutions of inulin and other substances used to determine glomerular filtration is difficult, in the clinic, its measurement by K. of endogenous creatinine gives quite satisfactory results. When a substance is excreted only by the kidney, then its K can be determined. Without taking urine, if the rate of administration of the substance is regulated so that its plasma concentration is maintained at a constant level, then the amount of the administered substance is equal to its K.

Since the definition of renal K. is associated with a study of the concentration of a test substance in the urine, one cannot ignore the transport of water in the kidneys, as well as their ability not only to excrete, but also to retain certain substances in the body. In the latter case, the concentration of the substance in the urine will be less than in the blood plasma. To determine whether a given substance is excreted by the kidney, use the calculation of K. according to the formula

C \u003d V (U - P) / P,

where U is the concentration of the substance in the urine. For substances whose concentration in urine is lower than in plasma, the resulting value of K. will be negative; this will indicate that the substance is retained in the plasma and excess water is released. The concept of positive and negative K. is important for characterizing the osmo- and ion-regulating function of the kidneys.

The use of radioactive isotopes as test substances significantly expanded the possibilities of clearance tests in the clinic, practice and increased their clinical significance. According to the decay curve of radioactivity over the heart, the effective renal plasma flow and blood flow are determined. Substances, K. which is used to determine glomerular filtration, but having radioactive isotopes in the molecule (inulin-131 I, EDTA-51 Cr, EDTA-169 Yb), allow research without collecting urine, which makes it possible to determine glomerular filtration with low diuresis . Isotope renography allows you to evaluate the funkts, the state of the kidneys in their various diseases, the evacuation function of the upper urinary tract; it is used to monitor the condition and function of the transplanted kidney (see radioisotope renography).

Clearance tests in hepatology are used to study the absorption and excretory function of the liver (see). At the same time, substances absorbed by the liver and excreted with bile (bilirubin, bromsulfalein, azorubin-S, rose bengal, vofaverdin, ueverdin, etc.) are introduced into the body. More often use bromsulphthalein test (see) and vofaverdin test (see).

To determine the hepatic parenchymal To. apply Bengal pink, labeled 131I, which has a pronounced hepatotropy. K. curves are processed using an exponential equation, calculating the half-life of elimination, the time of maximum radiation level over the liver, and the time the drug appears in the intestine. In liver diseases, the rate and degree of absorption and the degree of absorption and excretion of the dye decrease: with damage to polygonal cells, the absorption process suffers to a greater extent, and with inflammation, and especially biliary tract obstruction, the excretory function. It is especially important to compare the indicators of purification from the blood and liver preparations. In case of an obstruction to the outflow of bile, a normal or little-changed decrease in the drug from the blood is observed with a slow removal from the liver; simultaneous violation of the absorption of Bengal rose suggests damage to the parenchyma. With the help of clearance tests, it seems possible to identify anicteric forms of viral hepatitis, predictive assessment of the recovery period after acute viral hepatitis, the degree of damage and the dynamics of the process in hron, liver diseases.

To study regional blood flow, the so-called method is used. tissue clearance - the rate of elimination of isotopes 133Xe, 85Kr, albumin, labeled 131I, etc. from the tissue (organ) under study, in which the depot of the drug was created.

The prospect of application of clearance tests in a wedge, researches steadily extends. With their help, they study the metabolism of a number of substances, for example, albumin, the lifespan of erythrocytes, the production of bilirubin, biol, the hormone cycle, the rate of consumption of profactors and factors of the blood coagulation and anticoagulation system.

Determination of plasmatic K. finds application in the study of the pharmacokinetics of drugs, for the study of the absorption of drugs from went. - kish. a path, their distribution in an organism, a role of various bodies in their allocation or destruction. In addition, according to K., the effectiveness of cleansing the body of endogenous and exogenous substances is judged when using such methods of treatment as hemodialysis (see), peritoneal dialysis (see), hemosorption (see), lymphosorption (see), plasmapheresis ( see), exchange substitution of blood.

Bibliography: Gehmosorption, ed. Yu. M. Lopukhina, Moscow, 1977; Graf N e black grouse Y., etc. The value of plasma clearance in the study of the kinetics of antibiotics, Antibiotics, t. 5, no. 3, p. 56, 1960; Lopukhin Yu. M. and M o-lodenkov M. N. Hemosorption, M., 1978; Fundamentals of hepatology, ed. A. F. Bluger, p. 116, Riga, 1975; Shyuk O. Functional study of the kidneys, trans. from Czech., Prague, 1975, bibliogr.; I r about sh e in with to and y A. Ya. Clinical nephrology, L., 1971; Koi-shanp our E. Renal physiology, Philadelphia, 1976.

Yu. V. Natochin, M. E. Semendyaeva.

Nephrosis is a kidney disease that affects the tubules of the nephron. The nephron is the main structural unit of the kidney, there are at least 1 million of them. They act as a filter - they purify the blood and produce urine, which removes the body's waste products.

Only 35% of all nephrons are involved. The rest make up a reserve so that in the event of an emergency, the kidneys continue to perform their functions. Nephrons do not have the ability to recover, so the body after 40 years of age loses about 1% of their number every year. By the age of 80, this loss is already 40%, but it does not affect the functioning of the kidneys. But the loss of over 75% of nephrons has serious consequences, even death.

Causes and types of disease

The causes of the disease are as follows:

• infectious diseases.
• Renal pathologies: glomerulonephritis, pyelonephritis and kidney prolapse.
• A genetic disorder in the breakdown of proteins by the body.
• Poisoning by toxins or chemicals orally or by inhalation of vapours. Among the toxins there are special substances that affect the kidneys - nephrotoxins. These include, for example, poisonous mushrooms, acetic acid, ethylene glycol, a number of drugs, heavy metals.
• Transfusion of incompatible blood.
• Oncopathology.
• Deep skin lesions accompanied by infections.
• Systemic diseases (sarcoidosis, rheumatism, amyloidosis, syphilis).

Depending on the cause of occurrence, 4 types of the disease are distinguished, in which there is a degeneration of the renal tubules with a violation of their functions.

Renal amyloidosis

Amyloid nephrosis occurs when protein metabolism is disturbed. This occurs with a genetic pathology of protein synthesis (primary amyloidosis) or against the background of long-term infectious diseases (syphilis, tuberculosis, osteomyelitis).

Under the influence of infection, altered protein molecules are synthesized. In response, autoimmune processes occur, resulting in the formation of amyloid, a modified protein concentrate. It affects the vessels of the glomeruli of the nephron, where the purification of blood plasma takes place.

Necronephrosis

With necrotic nephrosis, there is a violation of the blood supply to the organ, due to which the structure of the epithelium of the tubules is destroyed.

The reason is exposure to infections or toxins. Renal failure develops

• liquid filtration is disturbed;
• the amount of urine is reduced to a minimum.

This increases the concentration of toxins, which increase the pathology in the renal tubule.

Post-transfusion and febrile nephrosis

Post-transfusion nephrosis is caused by careless blood transfusion. With the incompatibility of the blood of the donor and the recipient, red blood cells begin to break down, which causes shock.

Feverish nephrosis accompanies infectious diseases and is characterized by an increase in protein in the urine. It goes away on its own when the infection subsides.

Myoglobinuric nephrosis

The cause of this type of disease is alcoholism or heroin addiction. Under the influence of toxins, protein breakdown occurs in muscle tissues. At the same time, the level of myoglobin pigment increases, which is why the urine becomes reddish-brown in color.

Myoglobinuria develops, which causes damage to the renal tubules.

Lipoid nephrosis

Separately, it must be said about lipoid nephrosis of the kidneys - what it is, how it manifests itself and who most often suffers from it. This type of disease is rare and results in mild renal tubular dystrophy. Occurs after viral and bacterial infections. Recent studies show that autoimmune processes are involved in the development of lipoid nephrosis.

Children and adolescents, especially boys, suffer from lipoid nephrosis. Most often it is diagnosed at 2-4 years of age. The exact cause of this nephrosis has not been established. One of the hypotheses is an underdeveloped abdominal cavity and unformed body defenses. With age, relapses of the disease occur less frequently, and when remission occurs, children lead a normal lifestyle for healthy children.

Symptoms

Symptoms and treatment of nephrosis depend on the form of the disease. The main symptom of the disease is swelling. They are associated with an increase in the permeability of the walls of the nephron tubules for plasma proteins and a violation of protein metabolism. Proteins are excreted in the urine, which reduces their amount in the blood. This leads to a decrease in osmotic pressure in the blood vessels, and fluid enters the intercellular space.

In the early stages, the signs of the disease are poorly expressed, which does not contribute to timely diagnosis. But after conducting laboratory tests and examining the patient, the disease is diagnosed without difficulty.

With various types of kidney nephrosis, the symptoms, in addition to the general ones, have characteristic differences:

• Lipoid: slight swelling on the face (pastiness), accumulation of fluid in the peritoneum and pleural cavity, lower back pain, fatigue, weakness and poor appetite.
• Amyloid: fever, muscle pain, abnormalities in the liver and spleen, protein in the urine.
• Post-transfusion: a sharp increase in body temperature, severe chills. Bronchospasm makes breathing difficult, headaches and lumbar pain appear, and blood pressure drops. The skin, initially pale, becomes icteric due to an enlarged liver. There may be shock, involuntary urination or defecation.
• Necrotic: acute onset with pronounced signs of intoxication and shock kidney syndrome, protein in the urine.

Common symptoms of nephrosis include swelling, decreased urine output (oliguria), weakness, and dark urine.

There are 4 stages of swelling:

• I - swollen legs;
• II - edema extends to the genitals, lower abdomen and lower back;
• III - swelling of the neck and face is added;
• IV - generalized edema turns into a progressive form. The fluid accumulates not only under the skin, but in the organs and cavities.

An important symptom for detecting the disease in the early stages is a change in the laboratory parameters of urine, its darkening, the appearance of protein.

Treatment

If edema occurs, you should immediately contact a urologist, because nephrosis is easier to prevent than to cure. Nephrons are not restored and replenished. Necrotic nephrosis is better cured - subject to timely access to a doctor and the fulfillment of all prescriptions, although in severe cases of the acute phase, the patient may die from shock or anuria.

Worse treatable amyloidosis. Positive dynamics is only in the speedy transition to the stage of remission and an increase in its duration. Immediate visit to the urologist is the way to success.

The treatment of nephrosis is based on 3 cornerstones:

• elimination of the main cause of the disease;
• fight against edema;
• normalization of protein in the blood.

Treatment is carried out in the complex:

• drug and vitamin therapy;
• Spa treatment;
• diet.

Drug therapy is prescribed by a doctor, based on the type of disease and stage - acute or chronic. So, with lipoid nephrosis, the main task is to eliminate the source of infection. For this, antibiotics are prescribed. Treatment of nephronecrosis, first of all, requires the removal of toxins from the body, anti-shock measures. In the acute stage of amyloid nephrosis, blood transfusion is possible.

In any form of the disease, diuretics are prescribed to combat edema. If they are ineffective, drainage needles are inserted under the skin to drain fluid. Additionally, take decoctions of diuretic herbs. A strict diet is a supportive treatment. It cannot be neglected, but they adhere to it only during the period of exacerbation. It includes the following:

• Decreased salt and fluid intake.
• The content in food of a large amount of protein to make up for its loss in the urine. If the disease is complicated by glomerulonephritis, then the diet should be high in calories from fats and carbohydrates, and the amount of protein only covers its loss.
• Eating foods rich in vitamins.

Often with nephrosis, hypokalemia develops. Then potassium-containing products and pharmaceutical preparations are prescribed. When remission occurs, the patient is advised to take a varied diet containing the necessary nutrients, vitamins and minerals. Regular spa treatment is very useful.

Prevention

First of all, it is proper nutrition, the absence of bad habits, and increased immunity. To avoid injuries or bruises to the kidneys, care must be taken when playing sports or hard physical labor. You can not constantly wear squeezing underwear and clothing or leave the lower back bare. Colds and infectious diseases should be treated on time.

The mode plays an important role - regular, balanced nutrition, 8-hour sleep, walks in the fresh air, taking vitamins - this is what strengthens the body's defenses. The water regime is important - for the normal functioning of the kidneys, the daily need for pure natural water is at least 2 liters.

Kidney disease in children

Kidney disease in children is common. They suffer more often than adults, the cause of such disorders is a weak immune system. In addition, children endure any inflammation more difficult, with a number of complications. It is important to recognize the disease at an early stage so that the disease does not become chronic.

• Main reasons
• Congenital pathologies
• hydronephrosis
• Megaureter
• Multicystic
• Polycystic
• Violation of the structure of the body
• Acquired diseases
• Pyelonephritis
• Glomerulonephritis
• Cystic formations
• Expanded pelvis
• kidney failure
• Nephroptosis
• signs
• Diagnostics
• Therapy
• Prevention

Main reasons

The genitourinary system is formed at the stage of intrauterine development of the fetus. After birth, the paired organ continues to grow. A year and a half later? in children, the kidney is fully formed and has a normal size. Often, kidney disease is diagnosed in the first years of life, but sometimes anomalies are detected in adolescents.

The causes of the development of the disease are congenital or acquired. The first include defects that appeared during fetal development. The cause of such anomalies is the disease of the mother during pregnancy or her wrong lifestyle.

In children, kidney disease can result from:

• Postponed or chronic pathologies. Angina, tonsillitis, diabetes mellitus can provoke violations.
• Food, drink. The correct diet plays a huge role in the development and functioning of the kidneys. It is important to pay attention to the amount of fluid consumed, a normal volume of water does not allow pathogenic bacteria to be deposited in the ducts.

• The body's defenses. Kidney disease in children is often diagnosed with a weakened immune system.
• hygiene. It affects the condition of the genitourinary system in children and proper care, in the absence of regular washing, bacteria penetrate the kidneys and provoke inflammation.
• Hypothermia. A common cause of kidney disease in children is a cold of the kidneys, girls are most susceptible due to anatomical features.

Congenital pathologies

The most common cause of kidney disease is congenital anomalies. Such deviations are the result of an incorrect lifestyle of the expectant mother, past infections, hypothermia. These processes contribute to the development of inflammation of the kidneys in a pregnant woman, which passes to the fetus.

hydronephrosis

This disease is caused by stagnation of urine in the calyces of the kidney. The process occurs as a result of anomalies in the development of the ureter or lumen. These features are determined during examination of the fetus from the fourth month of intrauterine development. After birth, an operation may be required to normalize the functioning of the urinary organs.

Megaureter

There is a disease in the presence of reflux (vesicoureteral). In this case, urine returns from the bladder. The reason is an anomaly in the development of the valve or underdevelopment of the nervous system of the baby. Surgery is the best solution, and special gels are used as an alternative treatment.

Multicystic

Such a disease occurs in the fetus under the influence of toxic substances taken by the mother or as a result of genetic disorders. With such a disease, a change in the structure of the renal tissue occurs, while the organ is not able to perform its functions.

In the presence of a formation that does not exert pressure and does not interfere with the normal functioning of the kidneys, the cyst is left and monitored. Otherwise, surgical intervention is required.

Polycystic

The cause of the disease are disorders at the genetic level. In this case, the kidneys cope with their functions. You can live with such a disease, but it is possible that such a violation can cause kidney failure. With severe deviations, dialysis or a donor kidney transplant will be required. With PCOS, it is important to maintain a healthy lifestyle.

Violation of the structure of the body

In the presence of anomalies that arose at the stage of fetal development, as the child grows older, problems may arise in the functioning of the organ. Such disorders include doubling of the kidneys and ureter, horseshoe-shaped structure. With such changes, an operation is indicated, the optimal period is up to 1 year.

Acquired diseases

During the growing up of children, renal pathologies are possible, which occur for various reasons.

Pyelonephritis

It is characterized by inflammation, which appears on the background of hypothermia or as a result of past diseases. Sometimes it becomes the result of an operation performed on the urinary organs. With improper treatment, there is a risk of transition to the chronic stage. If therapy is started immediately, the disease can be quickly cured. Antibiotics are most often used to treat inflammation.

Glomerulonephritis

The renal glomerulus responsible for filtration suffers. The disease can occur in acute or chronic form. It develops as a result of past diseases, such as streptococcal infection, tonsillitis, scarlet fever.

Cystic formations

In the presence of growths on the kidneys, their nature is of great importance. Cysts are usually benign, but there is a possibility of transition to a malignant form. Therefore, children with kidney cysts are observed by a doctor. The cause of the development of such a disease is the reproduction of epithelial cells. With an increase in build-up in volume, an operation is required.

Expanded pelvis

It is a consequence of reflux, in which urine is released back. It may be the result of an abnormal structure of the vessels of the organ, which affects the structure of the tissues of the kidney.

Immediately after the birth of the child, experts recommend an ultrasound of the kidneys. This allows you to identify violations at an early stage and make a decision to prevent further development of the disease.

kidney failure

With such a pathology, the paired organ is not able to perform its functions. This contributes to electrolyte imbalance, uric acid accumulates in the patient's blood. Such a pathology can lead to organ failure, which entails the most severe consequences, up to death. Therefore, such a disease cannot be ignored.

Renal failure occurs against the background of pyelonephritis, abnormal structure of organs, proceeds in a chronic form. The cause of the acute stage may be the influence of toxic substances, which occurs against the background of an overdose of medications.

Nephroptosis

Due to an anomaly of the structure in children, in which the kidney is not sufficiently fixed. The organ is mobile, can turn around its axis, with such a movement, the vessels suffer, which provokes a violation of normal blood circulation.

ICD

The appearance of urolithiasis in children is the result of changes in the water-salt balance. Pathology occurs against the background of insufficient fluid intake or improper nutrition. Drinking plenty of water allows you to remove salts, prevents the formation of stones. There is a disease and against the background of insufficiency, when the mineral metabolism is disturbed. It is treated with a laser or with the help of surgery.

signs

Symptoms of kidney disease in children differ depending on the type and severity of the pathology. If developmental anomalies began at the stage of gestation, deviations can be determined by the following signs:

• an increase in the abdominal cavity;
• violation of the color of urine;
• urination with reduced pressure;
• subfebrile temperature;
• vomit;
• loose stool.

Kidney disease in newborns can cause yellowing of the skin as a result of metabolic disorders. A particularly dangerous sign is the absence of urine - this is a reason for immediate hospitalization. Convulsions and restless behavior during deurination also require medical attention.

Signs of kidney disease in older children may be latent, making it difficult to diagnose at an early stage. But there are characteristic signs that should not be ignored:

• painful urination;
• change in the composition and color of urine;
• the presence of "flakes";
• the smell of acetone;
• pain in the lower back and abdomen.

In the presence of inflammation, an increase in temperature is observed. Children refuse to eat, dry mouth appears. In the morning, swelling on the face is noticeable. Such symptoms in children are a reason to undergo a comprehensive examination.

Signs of kidney disease:

1. A pink tint to the urine is indicative of hematuria. Such a manifestation indicates the possible development of pyelonephritis, ICD, or injury to the urinary organs. The coloration of urine may indicate the intake of beets or grapefruit, such a change is not dangerous.
2. Swelling of the face and limbs may indicate kidney failure.
3. With rare urination and a small amount of fluid (anuria), CRF is possible.
4. Pale skin is a sign of glomerulonephritis.

Diagnostics

If any of the above symptoms appear, you need to undergo a thorough examination, including:

• Ultrasound of the urinary system;
• urography;
• blood and urine analysis.

To establish a diagnosis for violations of the kidneys in children, you need to contact a urologist or nephrologist.

Therapy

Treatment depends on the type of disease, is prescribed on an individual basis. Conservative methods of treatment are not always effective; in some cases, the problem can be solved only by surgery.

Drug therapy for kidney disease in children includes:

• drugs to reduce pressure;
• antihistamines;
• diuretic drugs;
• antibiotics.

In the presence of oncological formations, with KSD, as well as with renal failure, surgical intervention is required.

Prevention

In order for kidney disease to bypass the child, you need to follow some rules. You should start with the diet, spicy, fried, salty foods create an additional burden on the baby's kidneys. It is worth diversifying the diet with dairy products rich in calcium, juices. This will not only improve kidney function, but also strengthen the body's defenses. Children should eat cereals, vegetables and fruits, pumpkin.

It is very important to keep the lower back and legs warm, to avoid hypothermia. At the same time, it is necessary to temper the child's body, increase resistance to diseases. Follow your doctor's instructions if you have an infection. If a course of antibiotics is prescribed, you need to drink according to the schedule and to the end.

If warning signs appear, you should immediately seek medical help. Kidney diseases in children cannot be treated on their own, this can lead to serious complications.

Creatinine and urea are the final breakdown products. Their indicators are used to determine diseases of the liver, kidneys or study the condition of the muscles. Their indicators are always checked at the same time, as this allows you to determine whether the body has really failed in the natural excretion of decay products. Let's figure out why creatinine and urea in the blood are elevated.

Clearance (English clearence - cleansing) - an indicator of the rate of purification of blood plasma, other media or tissues of the body, i.e. is the volume of plasma completely cleared of a given substance per unit of time:

Renal clearance - clearance characterizing the excretory function of the kidneys, for example, clearance of urea, creatinine, inulin, cystatin C.

Since the kidneys and liver are mainly responsible for the elimination of drugs, an indicator such as clearance can be used to quantify it. So, regardless of what mechanisms a particular substance is excreted by the kidneys (filtration, secretion, reabsorption), in general, the renal excretion of this substance can be judged by how much its serum concentration decreases when passing through the kidneys. A quantitative indicator of the degree of removal of a substance from the blood is the extraction coefficient E (for processes that obey first-order kinetics, it is constant):

E \u003d (Ca-Cv) / Ca

where Ca is the serum concentration of a substance in arterial blood,

Cv - serum concentration of the substance in venous blood.

If the blood, when passing through the kidneys, is completely cleared of this substance, then E \u003d 1.

Renal clearance Clpo is equal to:

where Q is the renal plasma flow,

E - extraction coefficient.

For benzylpenicillin, for example, the extraction ratio is 0.5 and the renal plasma flow is 680 ml/min. This means that the renal clearance of benzylpenicillin is 340 ml / min.

The clearance of substances with a high extraction coefficient (for example, in the elimination of paraaminohippuric acid by the kidneys or propranolol by the liver) is equal to the plasma flow through the corresponding organ. (If a certain substance binds to blood cells and at the same time the bound fraction is quickly exchanged with the free one (in plasma), then it is more correct to calculate the extraction coefficient and clearance not for plasma, but for whole blood).

Best of all, the elimination of a substance reflects its total clearance. It is equal to the sum of clearances for all organs where the elimination of a given substance occurs. So, if elimination is carried out by the kidneys and liver, then

Сl \u003d Сlpoch + Сlprec

where Cl - total clearance, Clpoch - renal clearance, Clech - hepatic clearance.

Benzylpenicillin, for example, is normally eliminated both by the kidneys (Clpoch = 340 ml/min) and by the liver (Clpec = 36 ml/min). Thus, its total clearance is 376 ml / min. If the renal clearance is halved, then the total clearance will be 170 + 36 = 206 ml / min. With anuria, the total clearance becomes equal to the hepatic one.

Of course, only that part of the substance that is in the blood undergoes elimination, and it is precisely this elimination that the clearance reflects. In order to judge, on the basis of clearance, the rate of removal of a substance not only from the blood, but also from the body as a whole, it is necessary to correlate the clearance with the entire volume in which the substance is located, that is, with Vp (volume of distribution). So, if Vp \u003d 10 l, and Cl \u003d 1 l / min, then 1/10 of the total content of the substance in the body is removed in one minute. This value is called the elimination rate constant k.

Creatinine is a special molecular product that occurs as a result of various chemical processes (metabolism) in human muscles. Due to chemical reactions - protein metabolism - huge energy is released into the body, which leads to muscle contraction. This is how creatinine appears. It comes exclusively from the creatine molecule, which is responsible for muscle tone and energy supply.

Once creatinine is created, the body no longer needs it. Therefore, it is excreted into the blood. Further, after moving throughout the body with the help of the circulatory system, creatinine is delivered to the kidneys. The kidneys filter and creatinine is completely excreted in the urine. Such filtration of the kidneys occurs constantly and without interruption throughout the day. Even when no physical activity is performed, the diet and time of day change. Therefore, creatinine as a by-product does not have time to adversely affect the human body.

Creatinine is necessary for the metabolism of muscle tissues, and in the blood and urine of an absolutely healthy person, it is always present in a small dose. It is the level of creatinine in the blood that indicates whether the kidneys are functioning well enough. Only through the kidneys does it leave the body in the same amount as it is formed. And when there is a lot of creatinine in the blood, it means that the kidneys cannot cope.

There is a special calculation used in determining GFR - the glomerular filtration rate (blood circulation of the kidneys). Glomeruli are microbundles of blood vessels in nephrons - kidney filters. This calculation is the most accurate analysis that shows how much blood plasma the kidneys can filter from creatinine and excrete it into the urine in 60 seconds. The value obtained is the creatinine clearance.

Normal creatinine clearance

Creatinine clearance is an indicator that is quite different in everyday life for various reasons - the psychological and physical state of the patient's body, time of day, age and gender of the patient, body weight, and improper kidney function.

For a particular patient, the normal level of creatinine clearance is individual. But there are general ideal norms of indicators:

• Up to 30 years of age for a man up to 146 ml per minute, for a woman up to 134 ml per minute
• up to 40 years of age for a man ideally 107-139 ml per minute (1.8-2.3 ml per second), for a woman under 40 years old 87-107 ml per minute (1.5-1.8 ml per second )

Creatinine clearance decreases by 1% every year. In the process of aging in old age, the normal rate is already 54-105 ml per minute.

When and in what cases are creatinine clearance studies prescribed?

Creatinine clearance measures the rate at which blood flows through the kidneys. Changes in the norms of indicators in the diagnosis of creatinine clearance indicate a decrease in kidney filtration and, as a result, kidney failure, acute or chronic. Analysis of creatinine clearance is prescribed as a test of kidney function in the following situations:

• In case of renal insufficiency
• during pregnancy
• with pyelonephritis
• with congenital anomalies of the kidneys
• in the diagnosis of diabetes and other endocrine diseases
• patients after hemodialysis
• for assessing muscle loads in athletes, astronauts
• in experimental medicine

Definition, creatinine clearance formula.

To determine the functioning of the kidneys, there are 3 main ways to determine creatinine clearance:

1. Analysis of urine collected by the patient within 24 hours
2. Blood analysis according to the calculation formula. This diagnosis is carried out most often, being the most convenient for the patient.
3. Reberg's test

Analysis of urine. When diagnosing the level of creatinine clearance in this way, the patient collects his urine in a certain volume in a clean container within 24 hours, refusing the day before and within exactly 24 hours from the time of the first urine collection from caffeine and tea, beets and products with non-natural dyes. Keep the container with the collected urine either in a cool and dark place or in the refrigerator. Urinalysis determines the cleanliness of the kidneys when removing substances harmful to the body.

Blood analysis. There is a special formula for calculating creatinine clearance. The main parameters are the age and weight of the patient and necessarily the level of creatinine in the venous blood. The formula is: (140-age)*(body weight in kg)/(72*creatinine level in mg/dL). When calculating, a female patient needs to multiply the result obtained by the formula by an index of 0.85

2 days before blood sampling, any physical activity is prohibited so as not to increase the daily normal creatinine in the muscles. The day before the analysis, give up meat, legumes, pastries and fatty foods. You need to drink up to 2 liters per day. In the morning before the analysis, you can not eat. Especially in this method, attention should be paid to the children's formula, which differs from the formula for adults, because age is one of the main indicators in the calculation: the length of the child's body in cm / (0.0113 * blood creatinine level, µmol / l) * K . The "K" value in this formula is the child patient's age factor. In children aged 2-14 years and girls over 14 - a coefficient of 0.55, in boys over 14 - 0.7, in a full-term child under 2 years - a coefficient of 0.45, in premature babies - a coefficient of 0.33.

When the clearance of endogenous (muscle) creatinine falls below the norm indicated in the previous chapter, this is an indicator of chronic kidney disease. At a level of less than 60 ml per minute, the kidneys are considered damaged, and at a rate below 20 ml per minute, a severe form of renal failure is definitely established.

Reberg-Tareev test. This method is also called endogenous creatinine clearance, glomerular filtration rate (GFR) and is considered more accurate. Collection of urine and blood test at the same time. Before giving up, you need to drink 0.5 liters of water, preferably in the morning on an empty stomach. The first urine is skipped, it is collected during the second urination, when a blood test is taken at the same time. This study diagnoses many problems of kidney disease. Normally, according to the calculation of the Reberg-Tareev test, the indicator is 65-125 ml per minute.

If the result of GFR is underestimated, renal failure is detected. GFR with a score of 30-59 indicates chronic renal failure. The result is below 30 - the lack of working capacity of the kidneys, dialysis is urgently prescribed.

The norm and tests for the presence of creatinine in the blood

The level of blood creatinine is a constant value and is measured in micromoles / liter. In order not to lose control of the correct filtration function of the kidneys, it is important to monitor the creatinine level with the help of tests and kidney samples.

The appointment of an analysis for the presence of creatinine in the blood in cases where:

• assessment of kidney function is necessary in case of chronic renal failure
• hemodialysis is prescribed with a critical indicator of creatinine in the blood
• suspected urolithiasis
• the subject decided to become a kidney donor

In preparation for the analysis, 2 days before blood donation, refuse increased physical activity, you can’t drink coffee, tea, alcohol a day, you can’t eat meat and protein products, don’t eat half a day before the analysis, drink only water without gas.

Human muscles are the main source of creatinine production. The musculature of a man is very different from that of a woman. Therefore, normal levels of creatinine in the blood of men and women have different values, in men this figure is naturally higher. Also, in addition to the indicator of muscle mass, nutrition and how active the lifestyle is of no small importance. In athletes and those who train in the gym, creatinine levels can be significantly higher due to the increased consumption of amino acids in the body. In protein dieters and meat eaters, creatinine levels may also be elevated. The age and presence of pregnancy of the patient also matters.

The norm of creatinine in the blood:

• in an adult male 70-110 mmol / min
• in an adult woman 50-93 mmol / min
• in newborns and children up to a year 18-35 mmol / min
• in adolescents under 15 years of age 27-75 mmol / min

Elevation of creatinine in blood tests. The reasons.

Sometimes the level of creatinine in the blood changes slightly or greatly. This happens for various reasons:

1. When creatinine is not excreted from the body due to kidney damage (urolithiasis, kidney failure, pyelonephritis, glomerulonephritis, uremia), reduced blood supply to the kidneys, severe shock.
2. When there is an increase in creatinine in the blood. There are a lot of factors here - endocrine diseases (diabetes mellitus), frequent irradiation of the body, excessive physical activity (weightlifting, bodybuilding, improper diet (large amount of protein intake), abuse of sports nutrition, with an increased content of growth hormone in the body (gigantism), heavy skin injuries and operations, destruction of muscle tissue (squeezing) due to car accidents, various infectious diseases, loss of large amounts of blood, internal ulcers and tumors, anemia.

Symptoms of elevated creatinine are fatigue, fatigue, shortness of breath, a feeling of exhaustion of the body, and confusion.

Treatment for increased creatinine depends on the degree of the indicator. If this did not particularly affect the general condition of the body and the indicator is within the acceptable norm, doctors recommend a special diet, reduced physical activity, increased consumption of clean drinking water, diuretics, antioxidants to remove toxins and toxins, sleep normalization. If the indicator deviates significantly from the norm, you need to contact a specialist who will select the right treatment.

Decrease in creatinine in blood tests and its causes

A low creatinine level is also a pathology and affects the body negatively. The reasons for it are as follows: low muscle mass, severe muscle injuries, low protein diet, cirrhosis of the liver, pregnancy, amputation of limbs, long-term treatment with allergy drugs, vegetarian diet, blockage of the urinary tract.

In this case, you can not engage in self-compilation of a diet based on diets and hunger strikes, and minimize sports. Taking drugs under the supervision of a doctor.

An increase, as well as a decrease, in the level of creatinine in the blood has quite serious consequences if you do not pay attention. Therefore, try to find out from your doctor during blood tests if there are any abnormalities.