What information is confidential. Regulatory framework for working with confidential documents. Algorithm for transporting confidential information to other enterprises

Clinical significance of glomerular filtration rate

Glomerular filtration rate in nephrology is a parameter of paramount importance, since this indicator determines the functional capacity of the kidneys. Regardless of the causes of impaired renal function (its decrease), the glomerular filtration rate decreases. There is a clear correlation between the severity of kidney disease and GFR. The glomerular filtration rate begins to decrease in the very early stages of renal dysfunction (much earlier than the onset of the first symptoms of the disease). Kidney pathology can be acute (developing over several hours or days) and chronic (slowly progressing over several months or years).

Depending on the glomerular filtration rate, acute and chronic kidney diseases can be determined, which can go into the terminal stage (in this case, the patient's life will depend on renal replacement therapy - dialysis). In acute renal failure, the patient may be prescribed a single short-term dialysis; in chronic renal failure - lifelong dialysis or kidney transplantation.

It should be noted that at present, the theory of “acute kidney injury” dominates among specialists, which expands the possibilities of interpreting pathophysiology processes that occur when metabolic processes in the renal parenchyma are disturbed due to the action of various etiological factors (for example, with the nephrotoxic effect of xenobiotics, hemodynamic disorders, etc.). ). In some cases, such disorders cause an increase in the concentration of metabolites (urea and creatinine), which is usually considered as acute renal failure. But the introduction of more sensitive markers of damage to the structure of the kidneys makes it possible to carry out early diagnosis, thus providing effective therapy for damaged kidneys.

Studies have shown that in violation of ultrafiltration in the renal glomeruli, which is recorded by determining the GFR, there are not only significant violations of intrarenal metabolic processes, but also there is a significant activation of various pathological processes typical of the so-called "diseases of civilization", considered as a pandemic of metabolic pathologies. (first of all, diseases of the cardiovascular system: atherosclerosis and its complications - ischemic stroke, myocardial infarction, etc.). As a result, today specialists have begun to use a new integral concept - "chronic kidney disease" (CKD). This definition should be understood as a cumulative pathophysiological condition with various corresponding nosological disorders. That is, chronic kidney disease is a laboratory diagnosis with certain clinical consequences.

Estimation of glomerular filtration rate by the level of creatinine in the blood

Although high levels of urea and creatinine in the blood are a sign of a decrease in glomerular filtration rate, these indicators are not considered a direct measurement of it. The concentration of these metabolites increases when kidney function is reduced by more than 50%. That is, based on the indicators of creatinine and urea, it is impossible to detect kidney disease at an early stage. Of course, this does not apply to the diagnosis of acute renal failure, the development of which occurs so rapidly that the glomerular filtration rate in any case is reduced by more than 50%. With normal values of the concentration of urea and creatinine in the blood, acute renal failure can be safely excluded. But this is not enough to safely exclude chronic renal failure.

Glomerular filtration rate is ideally assessed by direct measurement. Such a measurement can be carried out, but this method is very complex and expensive, so it is practically not used in everyday practice. Until recently, glomerular filtration rate was measured using the creatinine clearance: the level of creatinine in the blood plasma and the level of creatinine in the daily portion of urine are determined. This method has many disadvantages, one of which is the collection of daily urine. Today, this test is practically not used - since 1999, the glomerular filtration rate has been calculated using a modified formulaMDRD.

GFR = 186 × ([serum (plasma) creatinine + 88.4] -1.154) × age -0.0203 × 0.0742 (female) × 1.21 (black),

where unit of measurement GFR is ml/min; creatinine blood serum (plasma) - µmol/l; age- complete years.

In addition, GFR can be calculated using the MDRD formula (Am. J. Kidney Dis, 2002) based on age, sex, race, and concentrations of creatinine (mmol/l), urea (mmol/l) and albumin (g/dl). ) in blood:

GFR = 170 x (creatinine x 0.0113) -0.999 x age 0.176 x (urea x 2.8) -0.17 x albumin 0.318

The resulting value for women is multiplied by 0.762, for people of the Negroid race - by 1.18.

The latter method of assessment makes it possible to determine the value of the glomerular filtration rate in most patients without resorting to urine collection (that is, without measuring diuresis and creatininuria), thus reducing costs while maintaining clinical information.

Studies have shown that the calculation method for calculating the glomerular filtration rate is much more accurate, as well as more convenient and cheaper than the previously used creatinine clearance. The MDRD method is recommended by many leading medical and scientific institutions and has been adopted by many modern laboratories (see also).

Table 1 shows the values of the glomerular filtration rate and their corresponding stages of chronic renal failure.

TABLE 1. GLOMERULAR FILTRATION RATE (GFR) IN CHRONIC RENAL INSUFFICIENCY (CRF)

Stage	GFR, ml/min	description
		Renal function is normal. There are signs of kidney disease (for example, protein in the urine)
		Moderate decrease in kidney function

		Significant decrease in kidney function
		A sharp decline in kidney function
		Renal failure in the terminal stage

It should be noted that current standards recommend determining the level of creatinine and GFR in all patients with chronic kidney disease every 3-12 months (the frequency of tests depends on the degree of kidney damage). In addition, individuals at high risk of developing kidney disease are advised to have a study every 12 months.

Recommendations for the annual determination of serum (plasma) creatinine levels

Regular testing for the level of creatinine in the blood is recommended for adults with a high risk of developing chronic kidney disease. These patients include:

Diabetes
Cardiac ischemia
Various pathologies associated with atherosclerosis
Heart failure
Hypertonic disease
Rheumatoid arthritis
nephrolithiasis
Systemic lupus erythematosus
Persistent proteinuria
myeloma
Hematuria of unknown etiology
Patients taking long-term drugs with potential nephrotoxic effects

Accurate assessment of glomerular filtration rate

It is necessary to pay attention to the fact that the MDRD formula allows only a rough estimate of the glomerular filtration rate. This formula cannot be used in the case of acute renal failure (although this may not be done with acute renal failure - it is enough to know the level of urea and creatinine in the blood).

Another significant drawback of this formula is that the data obtained using it can be mistaken for reduced kidney function in people with a normal (or almost normal) glomerular filtration rate (60-90 ml / min). That is, using only this formula, one can mistakenly diagnose chronic renal failure of stage 1 or 2 in persons with absolutely normal kidney function. It was this problem that prompted specialists to develop a more accurate formula for calculating the glomerular filtration rate based on the level of creatinine in the blood.

In 2009, studies were carried out on the formula CKD-EPI, which showed that it can be used to determine the glomerular filtration rate much more accurately in individuals with normal or slightly reduced renal function. Most likely in the near future, the CKD-EPI formula will completely replace MDRD.

The structural unit of the kidneys is the nephron, which is responsible for the process of filtering the blood. In the two urinary organs, about two million nephrons are collected, which are woven in groups into small balls. This is the glomerular apparatus (glomerular), in which glomerular filtration of the kidneys occurs.

Important: during the day, from 120 to 200 liters of blood passes through the nephron glomeruli. At the same time, it is in the nephrons that the separation of all toxins and decay products of proteins, carbohydrates and fats takes place.

The principle of the filtration process

The process of filtering the kidneys is quite simple and straightforward. First, blood enriched with oxygen and other nutrients enters the kidneys, namely the glomerular apparatus. In the nephrons, which have a kind of "sieve", there is a separation of toxic substances and other decay products from water. After such a division, water and useful trace elements (glucose, sodium, potassium) are absorbed back. That is, the process of reabsorption takes place. And all the toxins continue their movement through the nephron tubules to the renal pyramids and further into the pyelocaliceal system. Secondary urine is already formed here, which exits through the ureters, bladder and urethra.

Important: it is worth knowing that if a person’s kidneys are sick, then the nephrons in them slowly die one by one. Thus, the filtering function of the urinary organs gradually decreases. It must be remembered that nephrons, like nerve cells, cannot be restored. And those nephrons that take on a double and triple load, eventually cease to cope with their function and soon fail.

Factors that may affect the change in GFR

The rate of filtration in the glomerular apparatus depends on such factors:

The rate of plasma transport through the renal glomerular apparatus. That is, it means the volume of blood passing through the lumbar arteriole in a certain unit of time. Normally, this figure is 600 ml / min for a person with an average weight of 70 kg.
An indicator of pressure in the vascular system of the body. For a normal and healthy body is characterized by more high pressure in a vessel that bears than in a vessel that brings forth. AT otherwise the filtration process will be difficult and its speed reduced.
The number of healthy nephrons. The more the kidney is affected by the pathological condition, the smaller the filtering area becomes. That is, the number of healthy nephrons decreases.

GFR estimate

To assess the filtration function of the urinary organs, it is necessary to find out the GFR (the rate of the filtration process), which is calculated in ml / min. And the very work of the urinary organs is evaluated by the amount of creatinine in the urine collected from the patient. In order to correctly determine the level of creatinine, it is necessary to collect the daily volume of urine from the patient.

As for the removal of the glomerular filtration rate (GFR), for this it is necessary to collect urine from the patient using a similar method. Normally, the glomerular apparatus of healthy organs pumps up to 120 ml / min. At the same time, it is worth knowing that in patients in the 55+ age group, the rate of metabolic processes decreases, which means that the rate of blood filtration in the kidneys also decreases. The GFR is the rate of formation of primary urine from the filtrate in a certain unit of time.

Important: Normally, kidney filtration in healthy organs occurs at a constant rate and remains unchanged until the development of pathological processes in the urinary organs.

Pathologies that determine GFR

Pathological processes that change the glomerular filtration rate of the kidneys to a lower side can be very diverse. In particular, GFR is affected by such pathologies and diseases:

Chronic renal failure. In this case, an increased concentration of creatinine and urea will also be noted in the urine. That is, the kidneys do not cope with their filtering function.
Pyelonephritis. This inflammatory and infectious disease primarily affects the nephron tubules. And only then does the decline in GFR occur.
Diabetes. And also with hypertension (high blood pressure), lupus erythematosus, an increased speed of the kidney filtration process is observed.
Hypotension (low blood pressure). As well as a state of shock and heart failure can provoke a decrease in GFR to significant limits.

Help in diagnosing diseases

Measurement of GFR makes it possible to identify various diseases and pathological conditions at an early stage. At the same time, in order to track the filtration process in the kidneys, the method of introducing inulin into the blood, a special control substance that is excreted through the glomerular apparatus, is often used. Inulin is administered continuously for the duration of the study in order to maintain a constant concentration in the blood.

Urine sampling for analysis while maintaining the level of inulin is carried out four times with an interval of half an hour. But it is worth knowing that this method of analyzing the condition of the kidneys is quite complicated and is applicable only in scientific purposes.

It is also possible to estimate GFR by the level of creatinine clearance, which directly depends on the patient's lean body mass. It is worth knowing here that in active men, creatinine clearance is significantly higher than in women and children. Note that creatinine exits the body exclusively through the glomerular apparatus. Therefore, if the filtration process in the kidneys is impaired, the concentration of creatinine in the urine rises and is 70% compared to the GFR.

Important: when conducting a urine test for creatinine, you need to know that drugs can greatly distort the result. Normally, the level of creatinine for men is 18-21 mg / kg, and for women 15-18 mg / kg. If the indicators are reduced, this may indicate a malfunction in the kidneys.

This technique for studying the work of the urinary organs is carried out in this way:

In the morning, the patient is offered to drink half a liter of water on an empty stomach. After that, he must urinate every hour in order to collect portions of the biomaterial in separate containers.
When urinating, the patient is obliged to note the time of the beginning and end of the act.
And in the interval between taking portions of urine, blood is taken from the patient from a vein to determine the creatinine clearance. It is calculated using a special formula. The calculation formula looks like this - F1=(u1/p)v1.

Here the meanings are as follows:

Fi is glomerular filtration (its speed);
U1 - the content of the control substance in the blood;
Vi - the time of the very first urination after drinking water (in minutes)
p is the concentration of creatinine in blood plasma.

Calculate the creatinine clearance using the above formula every hour. In this case, the calculations are carried out during the day.

This is interesting: in normal men, GFR is 125 liters / min, and in women - 110 ml / min.

Calculation of GFR in children

To calculate the glomerular filtration rate in children, use the Schwartz formula. In the first case, a blood sample is taken from a vein in a small patient on an empty stomach. It is necessary to determine the level of creatinine in the blood plasma. Against the background of the biomaterial taken from the baby, two portions of urine are also collected at an hourly interval. And also note the duration of the act of urination in minutes or seconds. Calculations using the Schwartz formula make it possible to obtain two values of GFR.

For the second calculation method, the daily volume of urine is collected from a small patient at hourly intervals. Here the volume should be at least 1.5 liters. If, during the calculations, the result of the glomerular filtration rate is 15 ml / min (that is, it is greatly reduced), then this indicates renal failure or chronic kidney disease.

Important: GFR may not always fall against the background of nephron death. Often, the filtration rate can decrease against the background of an inflammatory process occurring in the kidneys. That is why, at the first suspicious symptoms (lower back pain, dark urine, swelling), it is urgent to contact a nephrologist or urologist.

Kidney Treatment and Restoration of Filtration Rate

In case of violations of the filtration function of the kidneys, treatment should be prescribed only by a specialist, depending on the root cause that led to the pathology. In most cases, the drugs "Theobromine" and "Eufillin" help to improve the situation. They increase diuresis, which leads to the normalization of GFR.

Also, against the background of treatment, it is necessary to follow a diet and drinking regimen. It is worth drinking up to 1.2 liters of fluid per day. And from the diet should be excluded all fried, fatty, salty, spicy, smoked. It will be better if the patient switches to steamed and boiled dishes for the duration of treatment.

If the attending physician allows, then you can adjust the glomerular filtration rate and folk remedies. Thus, common parsley, which improves diuresis, has been known for a long time to increase GFR. Its dry seeds and roots (in the amount of 1 tablespoon) are steamed with boiling water (500 ml) and incubated for 2-3 hours. Then the infusion is filtered and drunk twice during the day, 0.5 cups each.

Rosehip root can also be used to increase GFR. It is in the amount of 2 tbsp. pour boiling water and cook over low heat for 15 minutes. Then the broth is filtered and drunk 70 ml three times a day. Such a drug also increases diuresis, which will definitely increase GFR.

It is important to know that only a specialist should control the entire treatment process. Self-medication is strictly prohibited.

The kidneys are the natural filter of the body, with the help of which metabolic products, including dangerous toxins, leave the body. In total, they can process up to 200 liters of liquid in 24 hours. After all harmful elements are removed from the water, it returns to the blood again.

Often, as a diagnosis of the effective functioning of the kidneys, the determination of the glomerular filtration rate is used, the norm of which is different for each person.

What is it, what does it show and in what units of measurement?

The main problem of the kidney is that under the influence of a strong load, the death of nephrons occurs.

As a result, as a filter, it works worse and worse, since new elements will no longer be formed. As a result, there are a lot of different diseases and complications. This is especially prone to people who drink alcohol, eat a lot of salty foods and have poor heredity.

If, based on any symptoms, the doctor determines that the patient's complaints are related to the kidneys, he may be prescribed a diagnostic method such as GFR, that is, determination of glomerular filtrate velocity.

In this way, it is determined how quickly the filters in the body cope with the task that is, they cleanse the blood of harmful substances. This is the main one in determining some diseases, including.

In order to determine GFR, special formulas are used. There are several of them, and they differ in information content. But everywhere they use one term, namely clearance. This is an indicator by which you can determine how much blood plasma will be processed in one minute.

Normal values

Experts note that there is no clear norm for GFR, since each organism individual indicators. However, there are certain boundaries for each age and gender:

men - 125 ml / min;
women - 110 ml / min;
for children under 12 years old - 135 ml / min;
in newborns - about 40 ml / min.

During normal operation of natural filters, the blood will be completely purified. about 60 times a day. With age, the quality of the kidneys deteriorates, and the intensity of filtration becomes less.

Classification of chronic kidney disease by GFR

There are 3 main types of diseases that reduce or increase the filtration rate. According to this indicator, you can get a preliminary diagnosis, and additional ones will give a clearer picture.

The class of ailments that cause a decrease in the rate of GFR include:

(See the stages of CKD in the table). This disease leads to an increased concentration of urea and creatinine. In this case, the kidneys cannot cope with the load normally, which leads to the gradual death of nephrons, and then to a decrease in the filtration rate.
Approximately the same happens with . This disease is infectious. Pyelonephritis is characterized by inflammatory processes that necessarily affect the tubules of the nephrons. This inevitably leads to a decrease in the glomerular filtration rate.
One of the most dangerous states can be considered hypotension. In this case, the disease is associated with very low blood pressure. All this can lead to heart failure and a decrease in GFR to critical values.

to the class of diseases that cause an increase in kidney function, should include:

diabetes;
high blood pressure (hypertension);
lupus erythematosus, which also leads to increased stress on the kidneys.

How to calculate?

For this diagnostic method, one of the key roles is played by filtration process speed. It is by this indicator that a dangerous disease can be diagnosed at an early stage. It does not give a complete picture of GFR, but it will definitely indicate the right direction in the search for an accurate diagnosis.

In order to calculate how much fluid the kidneys can process, use data on volume and time. Therefore, the final result will be displayed in ml/min. In addition, data on the amount in the urine are used. For this, a special analysis is carried out, in which it is necessary to collect urine throughout the day.

used to determine GFR. daily volume of urine. So specialists in the laboratory will be able to calculate the approximate volume of liquid per minute, which will be the filtration rate. Further, the indicators are compared with the norm.

The highest level of GFR should be in children around 12 years of age. Then the numbers start to drop. This becomes especially noticeable after 55 years, when metabolic processes are no longer so active in the human body.

The glomerular filtration rate can depend on several factors:

the volume of blood that is present in the body;
pressure in the cardiovascular system;
the state of the kidneys themselves and the number of healthy nephrons also play an important role.

If a person takes care of his health, these indicators should be normal.

According to the Cockcroft-Gault formula

This technique is considered one of the the most common, despite the fact that now there are more modern methods calculation of glomerular filtration rate.

The essence of the method is that in the morning on an empty stomach the patient drinks 0.5 liters of water. Then every hour he goes to the toilet and collects urine. At the same time, the biomaterial for further research in without fail collected in a separate container for each period.

The task of the patient will be to time the how long does it take to urinate. In the interval between trips to the toilet, the patient takes blood for laboratory testing for creatinine clearance. To determine it, a formula is used that looks like this:

F1=(u1\p)*v1, where

F stands for GFR;

u1 is the amount of the control substance in the blood;

p is creatinine concentration;

v1 - prolonged first act of urination after drinking water in the morning.

According to Schwartz

This method is most often used to determine the glomerular filtration rate in children.

Diagnosis begins with the fact that the patient takes blood from a vein. This procedure necessarily carried out only on an empty stomach. This will allow you to more accurately determine the level of creatinine in plasma.

Next, you need to collect urine. This procedure is carried out twice, but after an hour. In addition to the amount of fluid excreted by the body, the duration of urination is also necessarily detected. For this analysis, not only minutes, but also seconds are important.

With the right approach to the study, you can immediately get 2 values, namely the rate of fluid filtration by the kidneys and the level of creatinine. This is a very important indicator that can tell about the development of many diseases.

Can be used to diagnose children daily urine collection method. The procedure is carried out every hour. If as a result it turns out that the average is less than 15 ml / min, this indicates the development of certain diseases, including chronic ones.

k*height/SCr, where

height in cm

k - age coefficient,

SCr — serum creatinine concentration.

Most often this is due to the work of the kidneys, including their insufficiency, problems of the cardiovascular system and metabolic disorders. Therefore, at the first sign of a problem, such as pain in the lumbar region, swelling, and, you should immediately consult a doctor.

CKD-EPI

This method is considered one of the most informative and accurate when it comes to determining GFR. The formula was derived several years ago, but in 2011 it was supplemented and became as informative as possible.

Using CKD-EPI, it is possible to determine not only the glomerular filtration rate of the kidneys, but also how quickly this score changes with age under the influence of certain ailments. The main thing is that the specialist has the opportunity to observe changes in dynamics.

For different sex and age, the formula will change, but values such as creatinine level and age remain unchanged in it. For representatives of each gender there is a coefficient. You can calculate GFR using an online calculator.

MDRD

Despite the fact that this method, like the previous one, is very informative in terms of indicators of the state of the body's natural filter, MAWP is not used very often in our country. In general, these 2 methods are very similar, since the same indicators are used in the formula. However, the age and gender coefficient changes somewhat.

When calculating according to the MDRD method, the formula is taken:

11.33*Crk-1.154*age-0.203*k=GFR.

Here Crk will be responsible for the concentration of creatinine in the blood plasma, and k is the sex coefficient. Using this formula, you can get more accurate indicators. Therefore, this method of calculating GFR is very popular in European countries.

Glomerular filtration is reduced - why and how to treat?

Regardless of how GFR is defined, it must be remembered that this is only a preliminary diagnosis, that is, a direction for further research.

Therefore, it is too early to talk about suitable treatment at this stage. First you need to make an accurate diagnosis, determine the cause of what is happening in the body, and only then proceed to eliminate this problem.

But for emergency cases, when glomerular filtration is critically reduced, there may be used diuretics. These include Eufillin and Theobromine.

If a patient has a violation of GFR, that is, the indicators will be higher or lower than normal, it is necessary to adhere to the correct drinking regimen and a sparing diet that will not overload the kidneys. Salty, fatty and spicy foods should be completely excluded from the diet. For a while, you can switch to boiled and steamed dishes.

Folk remedies for the treatment of GFR problems can only be used with the approval of the attending physician.

Parsley is ideal for improving kidney function. It is useful both fresh and in the form of a decoction. Rosehip is considered a good diuretic. Its fruits are brewed with boiling water, insisted, after which they drink the drink three times a day for several days.

Kidney pathologies can be very dangerous, so the entire treatment process is mandatory should be supervised by a specialist. And here it does not matter whether tablets or herbal decoctions are used. Both of them, if used incorrectly, can cause very great harm to the kidneys.

Find out how the glomerulus of the kidney is arranged and its functions from the video:

Glomerular filtration is one of the main characteristics that reflect the activity of the kidneys. The filtration function of the kidneys helps doctors in diagnosing diseases. The glomerular filtration rate indicates whether there is damage to the glomeruli of the kidneys and the degree of their damage, determines their functionality. In medical practice, there are many methods for determining this indicator. Let's see what their essence is and which of them are the most effective.

What it is?

In a healthy state, the structure of the kidney has 1-1.2 million nephrons (components of the kidney tissue) that communicate with the bloodstream through the blood vessels. In the nephron there is a glomerular accumulation of capillaries and tubules, which are directly involved in the formation of urine - they purify the blood of metabolic products and correct its composition, that is, they filter the primary urine. This process is called glomerular filtration (CF). 100-120 liters of blood are filtered per day.

Diagram of glomerular filtration of the kidneys.

The glomerular filtration rate (GFR) is often used to evaluate kidney function. It characterizes the amount of primary urine produced per unit of time. The norm of speed indicators of filtration is in the range from 80 to 125 ml / min (women - up to 110 ml / min, men - up to 125 ml / min). In older people, the rate is lower. If an adult has a GFR below 60 ml / min, this is the first signal of the body about the onset of the development of chronic renal failure.

Back to index

Factors that change the glomerular filtration rate of the kidneys

The glomerular filtration rate is determined by several factors:

The rate of plasma flow in the kidneys is the amount of blood that flows per unit of time through the afferent arteriole in the renal glomerulus. The normal indicator, if a person is healthy, is 600 ml / min (the calculation was made on the basis of data on an average person weighing 70 kg). Pressure level in the vessels. Normally, when the body is healthy, the pressure in the afferent vessel is higher than in the efferent one. Otherwise, the filtration process does not occur. The number of healthy nephrons. There are pathologies that affect the cellular structure of the kidney, as a result of which the number of capable nephrons is reduced. Such a violation further causes a reduction in the area of the filtration surface, on the size of which the GFR directly depends.

Reberg-Tareev test

The reliability of the sample depends on the time when the analysis was collected.

The Reberg-Tareev test examines the level of clearance of creatinine produced by the body - the volume of blood from which it is possible to filter 1 mg of creatinine in 1 minute by the kidneys. Creatinine can be measured in clotted plasma and urine. The reliability of the study depends on the time when the analysis was collected. The study is often carried out as follows: urine is collected for 2 hours. It measures the level of creatinine and minute diuresis (the volume of urine that is formed per minute). GFR is calculated based on the obtained values of these two indicators. Less commonly used method is the collection of urine per day and 6-hour samples. Regardless of which technique the doctor uses, the patient is sutra, until he has had breakfast, take blood from a vein to conduct a study on creatinine clearance.

A creatinine clearance test is prescribed in such cases:

pain in the kidney area, swelling of the eyelids and ankles; impaired urine output, dark-colored urine with blood; it is necessary to establish the correct dose of medicines for the treatment of kidney diseases; type 1 and 2 diabetes; hypertension; abdominal obesity, insulin resistance syndrome; smoking abuse ;cardiovascular diseases;before surgery;chronic kidney disease.Back to the table of contents

Cockcroft-Gold test

The Cockcroft-Gold test also establishes the concentration of creatinine in the blood serum, but differs from the method described above for collecting materials for analysis. The test is carried out as follows: in the morning on an empty stomach, the patient drinks 1.5-2 glasses of liquid (water, tea) to activate the production of urine. After 15 minutes, the patient relieves a small need in the toilet to clear the bladder from the remnants of formations during sleep. Next is peace. An hour later, the first urine sample is taken and its time is recorded. The second portion is collected in the next hour. Between this, the patient is taking blood from a vein in 6-8 ml. Further, according to the results obtained, the creatinine clearance and the amount of urine that is formed per minute are determined.

Back to index

Glomerular filtration rate according to the MDRD formula

This formula takes into account the gender and age of the patient, so with its help it is very easy to observe how the kidneys change with age. It is often used to diagnose kidney dysfunction in pregnant women. The formula itself looks like this: GFR \u003d 11.33 * Crk - 1.154 * age - 0.203 * K, where Crk is the amount of creatinine in the blood (mmol / l), K is a gender-dependent coefficient (for women - 0.742). In the event that this indicator in the conclusion of the analysis is given in micromoles (µmol / l), then its value must be divided by 1000. The main disadvantage of this method of calculation is incorrect results at increased CF.

Back to index

Reasons for the decrease and increase in the indicator

There are physiological reasons for changes in GFR. During pregnancy, the level rises, and when the body ages, it decreases. Foods with a high protein content can also provoke an increase in speed. If a person has a pathology of renal functions, then CF can both increase and decrease, it all depends on the specific disease. GFR is the earliest predictor of impaired renal function. The intensity of CF decreases much faster than the ability of the kidneys to concentrate urine is lost and nitrogenous waste accumulates in the blood.

When the kidneys are sick, reduced blood filtration in the kidneys is provoked by disturbances in the structure of the organ: the number of active structural units of the kidney decreases, the ultrafiltration coefficient decreases, changes in renal blood flow occur, the filtering surface decreases, obstruction of the kidney tubules occurs. It is caused by chronic diffuse, systemic kidney diseases, nephrosclerosis against the background of arterial hypertension, acute liver failure, severe heart disease, liver disease. In addition to kidney disease, GFR is affected by extrarenal factors. A decrease in speed is observed along with heart and vascular insufficiency, after an attack of severe diarrhea and vomiting, with hypothyroidism, prostate cancer.

An increase in GFR is a rarer phenomenon, but it manifests itself in diabetes mellitus in the early stages, hypertension, systemic development of lupus erythematosus, and at the beginning of the development of nephrotic syndrome. Also, medications that affect the level of creatinine (cephalosporin and similar in effect on the body) are capable of increasing the rate of CF. The drug increases its concentration in the blood, so when taking the analysis, falsely elevated results are detected.

Back to index

stress tests

Protein loading is the consumption of the required amount of meat.

The basis of stress tests is the ability of the kidneys to accelerate glomerular filtration under the influence of certain substances. With the help of such a study, the CF reserve or renal functional reserve (RFR) is determined. To recognize it, a one-time (acute) load of protein or amino acids is applied, or they are replaced by a small amount of dopamine.

Protein loading is a change in diet. It is necessary to consume 70-90 grams of protein from meat (1.5 grams of protein per 1 kilogram of body weight), 100 grams of vegetable proteins or enter an amino acid set intravenously. In people without health problems, there is a 20-65% increase in GFR as early as 1-2.5 hours after receiving a dose of proteins. The average value of PFR is 20−35 ml per minute. If the increase does not occur, then, most likely, the permeability of the renal filter is impaired in a person or vascular pathologies develop.

Back to index

The Importance of Research

It is important to monitor GFR for people with the following conditions:

chronic and acute course of glomerulonephritis, as well as its secondary appearance; renal failure; inflammatory processes provoked by bacteria; kidney damage as a result of systemic lupus erythematosus; nephrotic syndrome; glomerulosclerosis; renal amyloidosis; nephropathy in diabetes, etc.

These diseases cause a decrease in GFR long before the manifestation of any functional disorders of the kidneys, an increase in the level of creatinine and urea in the patient's blood. In a neglected state, the disease provokes the need for a kidney transplant. Therefore, in order to prevent the development of any pathologies of the kidneys, it is necessary to regularly conduct studies of their condition.

The kidney consists of a million units - nephrons, which are a glomerulus of vessels and tubules for the passage of fluid.

The nephrons remove waste products from the blood in the urine. Up to 120 liters of liquid pass through them per day. Purified water is absorbed into the blood for the implementation of metabolic processes.

Harmful substances are excreted from the body in the form of concentrated urine. From the capillary, under pressure generated by the work of the heart, liquid plasma is pushed into the glomerular capsule. Protein and other large molecules remain in the capillaries.

If the kidneys are diseased, the nephrons die and no new ones are formed. The kidneys do not perform their cleansing mission well. From the increased load, healthy nephrons fail at an accelerated pace.

Methods to evaluate kidney function

To do this, collect the daily urine of the patient and calculate the content of creatinine in the blood. Creatinine is a protein breakdown product. Comparison of indicators with reference values shows how well the kidneys cope with the function of cleansing the blood from decay products.

To find out the condition of the kidneys, another indicator is also used - the glomerular filtration rate (GFR) of fluid through the nephrons, which in the normal state is 80-120 ml / min. With age, metabolic processes slow down and GFR too.

Fluid filtration passes through the glomerular filter. It consists of capillaries, basement membrane and capsule.

Water with dissolved substances enters through the capillary indothelium, more precisely, through its holes. The basement membrane prevents proteins from entering the renal fluid. Filtration quickly wears out the membrane. Her cells are constantly being renewed.

Purified through the basement membrane, the liquid enters the cavity of the capsule.

The sorption process is carried out due to the negative charge of the filter and pressure. Under pressure, the fluid with the substances contained in it moves from the blood into the glomerular capsule.

GFR is the main indicator of kidney function, and hence their condition. It shows the volume of formation of primary urine per unit of time.

The glomerular filtration rate depends on:

the amount of plasma penetrating the kidneys, the norm of this indicator is 600 ml per minute in a healthy person of average build; filtration pressure; filter surface area.

In the normal state, GFR is at a constant level.

Calculation methods

Calculation of the glomerular filtration rate is possible by several methods and formulas.

The determination process is reduced to comparing the content of the control substance in the plasma and urine of the patient. The reference standard is the fructose polysaccharide inulin.

GFR is calculated using the formula:

V urine is the volume of final urine.

The clearance of inulin is a reference indicator in the study of the content of other substances in the primary urine. Comparing the release of other substances with inulin, they study the ways of their filtration from plasma.

When conducting research in a clinical setting, creatinine is used. The clearance for this substance is called Rehberg's test.

For the treatment of kidney diseases, our readers successfully use Galina Savina's method.

Checking kidney function using the Cockcroft-Gault formula

In the morning the patient drinks 0.5 liters of water and urinates into the toilet. Then every hour he collects urine in separate containers. And notes the time of the beginning and end of urination.

To calculate clearance, a certain amount of blood is taken from a vein. The formula calculates the creatinine content.

Formula: F1=(u1/p)v1.

Fi - CF; U1 - the content of the control substance; Vi is the time of the first (explored) urination in minutes; p is the content of creatinine in plasma.

This formula is calculated hourly. The calculation time is one day.

Normal performance

GFR shows the performance of nephrons and the general condition of the kidneys.

The glomerular filtration rate of the kidneys is normally 125 ml / min in men, and in women - 11o ml / min.

In 24 hours, up to 180 liters of primary urine passes through the nephrons. In 30 minutes, the entire volume of plasma is cleared. That is, in 1 day the blood is completely cleared by the kidneys 60 times.

With age, the ability to intensively filter blood in the kidneys slows down.

Help in diagnosing diseases

GFR allows you to judge the state of the glomeruli of nephrons - capillaries through which plasma enters for purification.

Direct measurement involves the constant introduction of inulin into the blood to maintain its concentration. At this time, 4 portions of urine are taken with an interval of half an hour. Then the formula is used to calculate.

This way of measuring GFR is used for scientific purposes. It is too complex for clinical trials.

Indirect measurements are made by creatinine clearance. Its formation and removal are constant and are directly dependent on the amount of muscle mass in the body. In men who lead an active life, creatinine production is higher than in children and women.

Basically, this substance is excreted by glomerular filtration. But 5-10% of it passes through the proximal tubules. Therefore, there is some error in the indicators.

When filtration slows down, the content of the substance increases sharply. Compared to GFR, it is up to 70%. These are signs of kidney failure. The picture of indications can distort the content of drugs in the blood.

And yet, creatinine clearance is a more accessible and generally accepted analysis.

For research, all daily urine is taken with the exception of the first morning portion. The content of the substance in the urine in men should be 18-21 mg / kg, in women - 3 units less. Smaller readings speak of

kidney disease

or improper collection of urine.

The simplest way to assess kidney function is to measure serum creatinine levels. As far as this indicator is increased, GFR is so reduced. That is, the higher the filtration rate, the lower the creatinine content in the urine.

Glomerular filtration analysis is done when kidney failure is suspected.

For the prevention of diseases and treatment of the kidneys and urinary system, our readers advise

Monastery tea of Father George

It consists of 16 most useful medicinal herbs, which are extremely effective in cleansing the kidneys, in the treatment of kidney diseases, diseases urinary tract, as well as when cleansing the body as a whole.

The opinion of doctors ... "

What diseases can be detected

GFR can help diagnose various forms kidney disease. With a decrease in the filtration rate, this may be a signal for the manifestation of a chronic form of insufficiency.

At the same time, the concentration of urea and creatinine in the urine increases. The kidneys do not have time to cleanse the blood of harmful substances.

In pyelonephritis, the tubules of the nephrons are affected. The decrease in glomerular filtration rate comes later. The Zimnitsky test will help determine this disease.

The filtration value increases with diabetes mellitus, hypertension, lupus erythematosus and some other diseases.

A decrease in GFR occurs with pathological changes, with a massive loss of nephrons.

The cause may be a decrease in blood pressure, shock, heart failure. Intracranial pressure rises with poor urine outflow. Due to increased venous pressure in the kidney, the filtration process slows down.

How is research conducted in children?

To study GFR in children, the Schwartz formula is used.

The rate of blood flow in the kidneys is higher than in the brain and the heart itself. it necessary condition filtration of blood plasma in the kidneys.

Reduced GFR can be used to diagnose early kidney disease in children. In clinical conditions, two of the simplest and most informative measurement methods are used.

Research progress

In the morning, on an empty stomach, blood is taken from a vein to determine the level of plasma creatinine. As already mentioned, it does not change during the day.

In the first case, two hourly portions of urine are collected, marking the time of diuresis in minutes. Calculating according to the formula, two GFR values \u200b\u200bare obtained.

The second option is to collect daily urine with an interval of 1 hour. You should get at least 1500 ml.

In a healthy adult, creatinine clearance is 100-120 ml per minute.

In children, a decrease to 15 ml per minute can be alarming. This indicates a decrease in kidney function, their painful condition. This does not always occur from the death of nephrons. It just slows down the filtration rate in each particle.

The kidneys are the most important cleansing organ of our body. If their functioning is disturbed, many organs fail, the blood carries harmful substances, there is a partial poisoning of all tissues.

Therefore, at the slightest concern in the kidney area, you should take tests, consult a doctor, undergo the necessary examinations and begin timely treatment.