Methods for examining urine in kidney diseases. What methods of kidney research are there? General clinical examination of urine

1. Cystoscopy- examination of the bladder using a cystoscope, which is a metal tube equipped with optical system. A cystoscope allows you to examine the mucous membrane of the bladder, determine the presence of ulcerations, papillomas, tumors, stones, and also carry out some therapeutic manipulations; Using a special thin catheter, you can take urine from each kidney separately for examination.

2. Chromocystoscopy– 5 ml is administered intravenously to the patient. 0.5-10% indigo carmine solution and then, through a cystoscope, observe the time of appearance of indigo carmine-stained urine from the mouths of the ureters. In a healthy person, colored urine begins to be released from the ureters within 3 to 5 minutes. after adding paint. If one of the kidneys is damaged, the release of colored urine from the corresponding ureter will be delayed or will not occur at all.

3. Panoramic photo of the kidneys. Its capabilities are limited; it is possible to identify oval shadows from the kidneys in their normal location on both sides of the spine between the XI thoracic and III lumbar vertebrae, and to detect stones in the kidneys and urinary tract. The best distinguishable stones are those consisting of calcium salts (oxalates, phosphates); stones made from uric acid salts are not visible on regular photographs. The ureters and bladder are also indistinguishable on a plain radiograph.

4. Excretory urography– the patient is injected intravenously with a contrast agent that is well excreted by the kidneys, then a series of radiographs are taken, from which one can judge the size and location of the kidneys, their functional ability (because they secrete urografin well), the size and shape of the renal pelvis, the location of the ureters and the presence of stones (stones).

5. Retrograde pyelography used only when excretory urography is insufficiently informative. The contrast agent is injected into the renal pelvis using special ureteral catheters through a cystoscope. Retrograde pyelography is performed in cases where the data obtained from excretory pyelography are not convincing enough to accurately establish the nature of the lesion of the renal pelvis or ureter.

6. Nephroangiography allows you to determine the state of renal blood flow. This is an X-ray examination method with the introduction of a contrast agent (diodrast, cardiotrast) using a special catheter through the femoral artery into the aorta at the level of the origin of the renal arteries.

7. Kidney scan. Using a special device - a gammatopograph or a scanner - the accumulation of the injected drug labeled in the kidneys is determined. radioactive isotopes, for example, neohydrin labeled with radioactive mercury. In this case, the shadows of the kidneys are recorded on a sheet of paper - a scanogram. The intensity of drug accumulation (shadow intensity) is used to judge kidney function. The presence of focal accumulation defects makes it possible to diagnose tumors, tuberculous kidney damage and other destructive processes. The scanogram can also determine the location, shape and size of the kidneys.

8. Radioisotope nephrography. The patient is injected intravenously with diodrast or hippuran, labeled I 131, then, using a multichannel radiographic installation, the function of each kidney separately, the rate of blood purification from the labeled drug (reflects the total secretory function of the kidneys) and the accumulation of the drug in the bladder, which is an indicator, are recorded in the form of characteristic curves. state of total urodynamics in the upper urinary tract system. The study allows you to get an idea of kidney function in chronic glomerulonephritis, tuberculosis, pyelonephritis, amyloidosis, and diagnose impaired urine outflow from one kidney.

9. Ultrasound – ultrasound examination of the kidneys widely used nowadays. It does not require special training and is quite informative. Ultrasound allows you to determine the topography of the kidneys, their size, changes in the parenchyma (cortical and medulla), and excretory system (wall compaction, size and deformation of the cups, pelvis). Echolocation is necessary to identify stones, cysts, and space-occupying formations.

10. Computed tomography (CT)– a modern x-ray research method that allows you to take pictures of the layers of the kidney at intervals of 1 cm or less.

11. Magnetic resonance imaging– the most accurate method of morphological diagnosis of kidney pathology.

12. Kidney biopsy. IN Lately In nephrology departments, percutaneous microbiopsy of the kidneys began to be performed for diagnostic purposes. A piece of kidney tissue for examination is taken using a special long biopsy needle and a suction syringe. The puncture is made from the lower back in the area of the kidney projection. The resulting piece of kidney tissue is examined under a microscope. To identify the pathogen in pyelonephritis, cultures are taken from the biopsy material and the sensitivity of the identified microbes to antibiotics is determined. Percutaneous microbiopsy is performed to determine the nature of the kidney tumor, diagnose chronic glomerulonephritis, and in a number of other cases. Percutaneous microbiopsy is performed strictly according to indications, as it can be accompanied by a number of serious complications.

Chronic renal failure syndrome (CRF)

chronic renal failure– a violation of the excretory function of the kidneys, which leads to a violation of the constancy of the internal environment, chronic intoxication of the body. CRF develops as a complication of chronic diseases accompanied by the death of glomeruli and secondary shrinkage of the kidney (chronic glomerulonephritis, chronic pyelonephritis, etc.). CRF also develops when the vascular system of the kidneys is damaged (hypertension, narrowing of the renal arteries, congenital or acquired), which leads to the development of a primary wrinkled kidney. Thus, changes in the kidneys come down to the predominance of sclerotic processes, hypertrophy of the remaining nephrons, which leads to a violation of the architectonics of the kidneys.

Stage I of chronic renal failure is latent. No complaints. Nitrogenous blood wastes are within normal limits. Compensatory polyuria and nocturia are observed, and in the Zimnitsky test there is isohyposthenuria. GFR is slightly increased.

Stage II chronic renal failure– complaints of weakness, increased fatigue. Moderate azotemia appears, polyuria, nocturia, and isohyposthenuria persist. But at this stage, the amount of urine begins to decrease compared to the first, GFR decreases.

III stage of chronic renal failure– azotemic uremia develops. The amount of urine is sharply reduced to anuria. GFR is significantly reduced.

Currently, to determine the functional state of the kidneys, the supernosological concept of “chronic kidney disease” has been introduced.

Chronic kidney disease (CKD) reflects the presence of kidney damage and/or GFR

Kidney damage– these are structural or functional abnormalities of the kidneys. Initially they may be detected when GFR is normal, but over time they can lead to a decrease in it. Markers of kidney damage include abnormalities in indicators characterizing kidney function, changes in urine analysis (leukocyturia, erythrocyturia, microalbuminuria, proteinuria), changes in the collecting system, stones, kidney cysts identified by ultrasound, CT or intravenous urography. All persons with kidney damage, regardless of GFR, are considered to have CKD. The classification of CKD is based on GFR calculated using the MDRD formula.

Laboratory diagnostics

Relative density of urine
The relative density of urine is measured using a urometer (a hydrometer with a scale of 1.000 to 1.050), which is lowered into a cylinder filled with urine during the test. The readings on the instrument scale correspond to the relative density of urine. Methods for determining the functional state of the kidneys by the relative density and amount of urine.

The body of a healthy person is able to regulate the amount and density of urine excreted depending on the volume of fluid drunk: if there is a lack of it, it produces a small amount of high-density urine, if there is an excess, the amount of urine increases, and its relative density decreases. Using this mechanism, the kidneys ensure constant volume and osmotic density of body fluids.

In case of kidney diseases, their concentration function, as well as the dilution function, is impaired. To identify these disorders, the Zimnitsky test and the Rehberg test are widely used.

Zimnitsky test

A renal function test is based on determining the amount and relative density of urine in three-hour portions during the day under the patient’s usual nutritional and drinking conditions. Urine is collected every three hours during the day (8 samples). The volume and relative density of each portion are determined.

Great importance is attached to the comparison of night and daytime diuresis. By examining the density of urine in different portions, its maximum value and range of fluctuations during the day are determined. Normally, daytime diuresis exceeds nighttime, the amount of urine in portions ranges from 50 to 250 ml, and the relative density from 1.005 to 1.028.

Zimnitsky's test reveals characteristic features functional kidney failure: polyuria (daily diuresis more than 2000 ml), decreased relative density of urine (up to 1.000–1.010) and nocturia (predominance of nighttime diuresis over daytime).

Dilution and concentration tests

Previously, the “dilution test” and the “concentration test” were widely used to assess the functional capacity of the kidneys. In the first case, the patient was given 1.5 liters of liquid to drink within 30 minutes, in the second case, liquid intake was limited for 36 hours. Urine was collected at certain intervals. The volume and relative density of each urine sample were determined.

Currently, these tests are not used due to their non-physiological nature and difficult tolerability by patients. Recently, methods have been developed to determine the nature of individual renal functions: glomerular filtration, renal plasma flow, tubular transport of various substances, the intensity of excretion of electrolytes and urea in the urine.

Method for determining the mass of active nephrons

In addition, to assess the functional state of the kidneys, the method of determining the mass of active nephrons has become important, making it possible to identify renal failure in which the mass of the active kidney parenchyma is 30% or less relative to the norm. The mass of active nephrons is assessed by maximum glucose reabsorption (normal is 110–120 ml/min) and glomerular filtration value (normal is 300–350 ml/min). Numeric value The mass of active nephrons determined by this method is not entirely accurate.

Clearance tests

To assess the excretory capacity of the kidneys, the so-called clearance tests (from clearance - purification), first proposed by Moeller et Van Slyke (1928), are widely used.

Clearance, or purification coefficient, is the volume of plasma that, passing through the kidneys per unit of time (1 minute), is completely cleared of a particular substance. To determine glomerular filtration, the clearance of substances that enter the urine only through glomerular filtration and are not reabsorbed in the tubules is calculated. These substances include creatinine, inulin, sodium thiosulfate.

The clearance of substances excreted only by glomerular filtration is calculated using the formula common to all clearances:

Where F is glomerular filtration (clearance), U is the concentration of the filtered substance in the urine, P is the concentration of the filtered substance in the blood plasma, V is the volume of urine excreted per minute. The values of U, V and P are clinically measurable. From them you can calculate the unknown value F.

Rehberg's test

Reberg proposed to study the value of glomerular filtration using endogenous or exogenous creatinine. This substance enters the urine only through glomerular filtration. Consequently, the creatinine content in blood plasma and glomerular filtrate is the same. Therefore, it is possible to determine how many times the glomerular filtrate is concentrated when passing through the tubules, that is, not only to determine the amount of glomerular filtration, but also to calculate the amount of reabsorption (the percentage of water reabsorbed). For this, the following formula was proposed:

Where R is the percentage of reabsorbed water, F is glomerular filtration (ml/min), V is the minute volume of urine (ml).

Rehberg tests can be performed both after water loading and without loading. Currently, the second option is more often used. From the subject on an empty stomach, blood is taken from a vein and the concentration of creatinine in it is determined.

Urine is collected either within two hours or within 24 hours. Diuresis is measured and creatinine content in urine is determined. Next, using the above formula, the glomerular filtration rate and the percentage of reabsorbed water are calculated.

In a healthy person, the glomerular filtration rate is: during the daytime - 53–113 ml/min, at night - 40–102 ml/min; after water load - 110–150 ml/min. Consequently, glomerular filtration has a diurnal rhythm (lower at night than during the day) and increases after water load.

A decrease in the value of glomerular filtration and a disruption of its circadian rhythm is observed in organic kidney damage: glomerulonephritis, pyelonephritis, etc. When creatinine clearance drops below 30–50 ml/min, azotemia and an increase in the concentration of creatinine in the blood plasma are observed. It should be noted that renal pathology is not always accompanied by a decrease in glomerular filtration rate. In addition, glomerular filtration can decrease with age, change under the influence of diet (increases with high protein content in food) and when taking large quantity liquids. Its value decreases with heavy physical activity and under the influence of emotions. A decrease in glomerular filtration can be observed with blood loss, shock, dehydration, and cardiovascular failure.

In healthy people, the amount of tubular reabsorption of water is during the day (98±0.1%), at night (99±0.1%), after a water load (97±0.3%).

A decrease in the percentage of water reabsorption occurs with pyelonephritis, acute renal failure, and the polyuric stage of chronic renal failure. With severe renal failure, tubular reabsorption is reduced to 80–60%. Substances that are not only filtered in the glomeruli, but also secreted in the tubules, give the so-called mixed (filtration-reabsorption or filtration-secretion) clearance, which makes it possible to assess the functioning of the kidneys as a whole. There are substances with very high clearance (diodrast, phenolrot, para-aminohippuric acid, etc.), close to the value of renal blood flow. Therefore, the amount of renal blood flow can be determined by the clearance of these substances.

Determination of renal plasma flow and glomerular filtration

In addition, substances labeled with 131I are used to determine the value of renal plasma flow and glomerular filtration. In healthy people, the value of renal plasma flow is 550–600 ml/min, the value of renal blood flow is 1150–1250 ml/min. Determination of renal blood flow is important for the differential diagnosis of the hypertensive form of chronic glomerulonephritis and hypertension - it is increased or normal in glomerulonephritis and decreased in hypertension.

Assessment of proximal tubule transport systems

To assess the transport systems of the proximal tubules and the number of functioning proximal tubules, the value of maximum tubular reabsorption of glucose is determined. Normally, all filtered glucose is reabsorbed in the tubules. Its excretion in urine begins when its concentration in the filtrate exceeds the reabsorption capacity of the proximal tubule cells.

Maximum glucose reabsorption characterizes the functional capacity of proximal tubule cells. Study of the biochemical composition of blood and some of its physical properties(nitrogen excretory, homeostatic, endocrine) can to a certain extent be assessed by the biological composition of the blood. If the endocrine, in particular hematopoietic function of the kidneys is impaired, the content of hemoglobin and red blood cells decreases. Dysfunction of the regulation of vascular tone leads to arterial hypertension.

Assessment of nitrogen excretion function of the kidneys

To assess the nitrogen excretory function of the kidneys, the content of residual nitrogen in the blood is determined. An increase in this indicator is observed when 1/3–1/2 of all nephrons are affected, that is, with significant insufficiency of the nitrogen excretory function of the kidneys, accompanying a severe degree of renal failure.

To determine the early stages of renal failure, it is more appropriate to determine not the amount of residual nitrogen, but its content in the plasma components(urea and creatinine), the levels of which increase much earlier than the level of residual nitrogen. It should be noted that an increase in the content of urea and all residual nitrogen may be due to extrarenal factors: hemolysis, increased tissue breakdown, protein-rich foods. Renal failure is supported by an increase in urea in total residual nitrogen of more than 50%. Many kidney diseases (glomerulonephritis, pyelonephritis, acute renal failure, etc.) are accompanied by an increase in the content of sodium, potassium, chlorine, and magnesium in the blood plasma due to a violation of the renal mechanism of electrolyte metabolism. During the period of intense convergence of edema, the content of sodium, chlorine and potassium in the blood plasma decreases. Along with the electrolyte composition of the blood, an indicator of the renal homeostasis mechanism is the alkaline reserve (the amount of bicarbonates associated with cations), which in healthy people is 27 mEq/L. In renal failure it decreases. In addition, in renal failure, the alkaline reserve (the total base reserve in whole blood) is reduced, which is normally 110 mEq/L.

To assess the functional state of the kidneys, plasma osmolarity (the content of osmotically active substances - urea, electrolytes) is also determined. An increase in blood plasma osmolarity above 280–300 mOsm/L and, consequently, a decrease in its freezing point below - 0.56 °C indicates impaired renal function. To a certain extent, an indicator of the functional state of the kidneys is the protein composition of the blood, which can indirectly give an idea of disturbances in protein filtration in the glomeruli and its reabsorption in the kidney tubules.

Instrumental diagnostics

Kidney ultrasound

Ultrasound examination of the kidneys is currently widely used in the diagnosis of congenital and acquired kidney diseases. This harmless diagnostic method allows you to accurately assess the size, contours and shape of the kidneys, the condition of the parenchyma, the collecting system and identify pathological processes such as tumors, stones, and kidney cysts. Ultrasound examination can also detect changes in the ureters, bladder and prostate gland.

X-ray examination

The kidneys are not visible on X-ray examination. On plain radiographs of thin people, it is often possible to identify oval-shaped shadows from the kidneys when they are normally located on both sides of the spine between the 11th thoracic and third lumbar vertebrae. In addition, shadows of kidney and urinary tract stones can be detected. Stones consisting of oscalates and phosphates are clearly visible; stones consisting of uric acid salts are not visible. The ureters and bladder are indistinguishable on plain films.

For diagnostic purposes, to clarify the size and shape of the kidneys, X-rays of the kidneys are taken after the introduction of oxygen into the retroperitoneal space (pneumoperitoneum) or into the perinephric region (premoroneum). At the same time, the shadows of the kidneys become visible.

Excretory urography is widely used, in which the patient is given a series of x-rays of the kidneys after intravenous administration of a contrast agent that is well excreted by the kidneys (for example, sergosine). The release of a radiopaque substance is used to judge the functional capacity of the kidneys. In addition, excretory urography allows you to obtain information about the size and location of the kidneys, the size and shape of the renal pelvis, the location of the ureters, and the presence of calculi (stones).

If the data obtained using excretory urography provide an incomplete picture of kidney damage, as well as if there are contraindications to intravenous administration of sergosine (hypersensitivity to iodide drugs included in its composition), retrograde pyelography is performed. In this case, a radiopaque substance (sergosine, cardiotrast) is injected into the renal pelvis using ureteral catheters or through a cystoscope. This method is technically complex and poorly tolerated by patients, so its indications must be strictly limited.

Simultaneous bilateral retrograde pyelography is unacceptable, as it can lead to serious complications. To study the blood flow in the renal artery and identify its disturbances (stenosis, atherosclerotic plaque), renal angiography (nephroangiographic) is used, in which a contrast agent (diodrast, cardiotrast) is injected using a special catheter through the femoral artery into the aorta at the level of the origin of the renal arteries.

For the study of the kidneys and urinary tract in the most difficult to diagnose cases, it can be used CT scan. This method makes it possible to detect even minor organic lesions of the kidneys, as well as stones of the ureters and renal pelvis. This study is expensive and involves radiation exposure of the patient, so its indications are limited.

Bladder catheterization

Catheterization of the bladder is carried out using a soft rubber sterile catheter lubricated with petroleum jelly. It is carried out for both diagnostic (taking a urine sample for examination) and therapeutic (emptying the bladder of accumulated urine in case of urination problems, washing the bladder with disinfectant solutions, etc.) purposes.

Bladder examination

To examine the bladder, cystoscopy is used (examination of the bladder using a cystoscope, which is a metal tube with an optical system). Cystoscopy allows you to study the condition of the mucous membrane of the bladder and identify pathological changes such as papillomas, tumors, stones, and ulcerations. In addition, with cystoscopy, it is possible to carry out some therapeutic measures, as well as take urine for examination from each kidney separately (using a special catheter) and determine kidney function (chromocystoscopy). During chromocystoscopy, the patient is injected intravenously with an indigo carmine solution (0.5% 5 ml), after which the appearance of indigo carmine-stained urine from the orifices of the ureters is observed through a cystoscope. Normally, colored urine begins to be released from the ureters 3–5 minutes after intravenous injection of dye. In case of kidney pathology, the release of colored urine from the corresponding ureter is delayed or does not occur at all.

Percutaneous kidney biopsy

For diagnostic purposes, the patient can undergo a percutaneous kidney biopsy, in which a piece of kidney tissue is taken for examination using a special long biopsy needle and a suction syringe. The puncture is made from the lower back in the area of the projection of the kidneys. The resulting material is examined microscopically and bacteriologically. Percutaneous biopsy allows you to determine the nature of the tumor process in the kidney, diagnose chronic glomerulonephritis, amyloidosis and a number of other diseases. In addition, bacteriological examination of a piece of kidney tissue makes it possible to identify the causative agent of the infectious process in the kidney and determine its sensitivity to antibiotics. The disadvantages of the method include frequent complications that it can provoke. Therefore, percutaneous kidney biopsy should be performed strictly according to indications.

Radioisotope research methods

Radioisotope renography helps to study the functional ability of the kidneys. In this case, the patient is injected with diodrast or hippuran, labeled with I131, and then, using a multichannel radiographic installation, the function of each kidney separately, the rate of blood purification from the labeled drug, and the accumulation of the drug in the bladder are recorded in the form of characteristic curves. Radioisotope renography helps determine the functional capacity of the kidneys in chronic glomerulonephritis, amyloidosis, pyelonephritis and a number of other renal lesions.

Kidney scan

Kidney function tests are also done using kidney scans. In this case, using a special device - a Gamma topographer (scanner) - the accumulation of an injected drug labeled with radioactive isotopes in the kidneys is determined. At the same time, shadows of the kidneys are recorded on a sheet of paper - a scanogram. The intensity of drug accumulation (shadow intensity) is used to judge kidney function. A kidney scan allows you to diagnose destructive processes in the kidneys (tumors, tuberculosis, etc.), in which defects in the accumulation of the drug are visible on the scanogram.

How to check your kidneys - everyone who is concerned about their health should know the answer to this question. There are quite a few types of diagnostics performed to examine the kidneys; Your general practitioner or nephrologist will tell you which one is indicated specifically in your case. Each test is carried out after certain preparation.

Who needs to have their kidneys examined?

It won’t hurt anyone to find out how the body’s main filter feels. Moreover, most studies are harmless, do not require special preparation and are performed fairly quickly. By medical indications A kidney examination is required in the following cases:

an increase in blood pressure above 139/89 mm Hg was detected.
decreased amount of urine
night urination
heaviness, pain or discomfort in the lumbar region
painful urination
unpleasant smell of urine
change in the color of urine, especially the appearance of blood in it
when anemia (low hemoglobin) is detected without acute or chronic blood loss
as: planned - when your diet is rich in meat and salty foods, you like chocolate, beer, offal, sorrel, spinach, legumes; urgently - when they appeared
with dehydration due to fever, vomiting, diarrhea, shortness of breath
if you are taking medications that are toxic to the kidneys: diuretics, Aspirin (Salicylic acid), Biseptol, Acyclovir, Amikacin, some other medications
and blood and urine tests are indicated if you feel unexplained malaise in the evenings, an increase in temperature to low numbers (up to 37.5 ° C)
at diabetes mellitus, systemic lupus, some other systemic diseases
with a palpable formation in the abdominal cavity

What types of kidney diagnostics are there?

There are two main types of tests, based on the results of which the doctor can judge the condition of the kidneys:

laboratory methods that can help you get an idea of the change
instrumental diagnostics: its methods make it possible to judge changes in the structure of the kidneys and urinary tract, and also provides information about the excretory function of the paired organ.

What are the laboratory diagnostic methods?

A laboratory examination of the kidneys includes the examination of two main biological fluids - blood and urine.

Substances such as urea, creatinine, and uric acid are determined in the blood (blood from a vein is donated for this). Based on a general blood test (it is taken from a finger), one can only draw a conclusion about the presence of anemia, the presence and degree of inflammation (without localization of the latter). Both tests are taken on an empty stomach.

In urine, the number of cells such as leukocytes, epithelium, and red blood cells is determined. The specific gravity, the presence of cylinders, protein and glucose, as well as pathological formations: salts, bacteria, fungi, mucus or other impurities are assessed. Urine has collection features depending on the type of analysis (general, according to Zimnitsky or Nechiporenko). It is advisable for everyone to undergo a general analysis at least once every six months; there are indications for taking the other two and the Rehberg test.

Instrumental methods

On this moment There are four types of diagnostic instrumental studies used to assess the structure of renal tissue:

Ultrasound examination (ultrasound of the kidneys) is a method that will only assess the structure, but not the function of the kidneys and urinary tract. Can be performed once a year as a routine examination.
Kidney X-ray: This general name covers several methods where an X-ray tube is used to visualize organs. Some require contrast injection (into a vein or urinary tract), while for others this is not necessary. This group of methods also includes. All of them are used strictly according to indications.
Radionuclide scintigraphy is a study of the kidneys using the injection of a radioisotope substance. Use only as prescribed by a doctor.
Magnetic resonance imaging. In this case, layer-by-layer visualization of the organ is provided by a special magnet. Unlike the previous two cases, there is no harmful radiation, but the method must be used according to indications.

The kidneys are a paired organ that performs filtration and excretory functions. By removing toxins and metabolic products from the human body, the kidneys are exposed to infectious diseases and may suffer from substance poisoning. The slightest destruction of functionality leads to infection of the entire body, so it is important to promptly pay attention to signs of possible kidney pathologies and conduct a kidney examination to stop diseases and normalize the condition of organs.

Important! As a rule, all renal pathologies develop with subtle symptoms such as lower back pain, changes in the volume of urine output, changes in the smell and color of urine, and temperature changes. You should listen carefully to the signs and consult a doctor without delay

Methods for diagnosing kidney diseases

Depending on your symptoms, kidney function tests may vary. But there are average parameters that are recognized by all doctors:

organ length 11-12 cm;
width 5-3 cm;
thickness (taken along the longitudinal line between the front and back surfaces) 3-4 cm and no more.

The density of the outer cortex should be higher than the inner one due to the high content of nephrons, while the medulla is equipped with a higher content of tubules. The renal sinus looks like a cavity connected to the pelvis with access to the ureter.

The following indicators are considered average standards when examining a portion of urine:

excretion per day is not less than 1.0 liters and no more than 2-2.5 liters;
shades from yellow to light yellow;
absence of sediment with clear urine;
liquid density 1005-1025 mg/l;
leukocytes no more than a few units; during pregnancy and the presence of certain pathologies, no more than 1 dozen are allowed;
protein up to 0.033 mg/ml or completely absent.

The choice of diagnostic method depends on the signs of the disease, medical history, the presence of pathologies in relatives and other factors. Therefore, the doctor always carefully collects the patient’s history and conducts an initial visual examination - palpation for organ enlargement. Then options such as:

laboratory research;
special.

Laboratory methods

Includes collection of urine and blood. Urine analysis is considered the most informative. In particular, the method allows you to see the water-excreting and contracting function of the kidneys. Water excretion is based on the volume of urine excreted per day in comparison with the volume of fluid consumed by the patient. Concentration is determined by measuring the specific gravity of urine portions. If highlighted:

small amount, possible diagnosis of oliguria;
lack of urine indicates anuria;
too high an excretion rate - polyuria.

All changes indicate the presence of an inflammatory process leading to organ dysfunction.

A decrease in specific gravity or the same readings in all portions may indicate a decrease in the concentration ability of urine. Additional samples are taken to clarify the diagnosis:

a water test consists of drinking 1.5 liters of water on an empty stomach and calculating the volume of fluid excreted over 4 hours of real time;
concentration is that the patient is recommended to eat food rich in protein (dry) during the day, then in the morning urine is collected every two hours to study the quantity and specific gravity of each portion.

For your information. If kidney function is normal, the result will be a rapid excretion of all the liquid drunk with a reduced specific gravity (1002-1004); with concentration tests, the volume of urine of each subsequent portion will be less as its specific gravity increases (from 1030).

Instrumental diagnostic methods

Ultrasound with assessment of renal structures, the condition of the urinary tract, and renal vessels.
X-ray methods that have wide range opportunities.
Radioisotope scanning with the introduction of a contrast agent.
MRI, CT to visualize the complete clinical picture of the condition of organs.

Now let's look at each method in a little more detail:

Ultrasound. The method helps determine the size and shape of the kidneys, and serves to diagnose congenital structural anomalies, identify chronic pathologies, the presence of cysts, tumors, and calculi not only in the kidneys, but also in the bladder. When examined using Doppler ultrasound, destruction of blood flow is determined.

Important! If the diagnosis is in doubt, patients are prescribed additional examination methods. Ultrasound does not always reveal hidden anomalies or the dynamics of the disease, so the indicators cannot be considered 100% correct.

X-ray. If a certain procedure is carried out without a contrast agent, for example, if the patient has allergies, the picture will be blurry, but may provide some features of the course of the disease. When a contrast agent is introduced, the clinical picture is complete: the position of the kidneys, size, presence of formations, pathological changes. Preliminary preparation includes complete emptying of the bladder and intestines. The procedure is carried out on an empty stomach and is one of the decisive ones for making the correct diagnosis.
Radioisotope survey can be of several types:

dynamic scintigraphy;
static scintigraphy;
renoangiography.

The procedure is considered the simplest and fastest diagnostic option, allowing one to examine the functionality of each of the paired organs separately. Before the procedure, a substance is injected and then excreted in the urine. The obtained readings are recorded on sensors and serve to make the correct diagnosis.

Tomography is an invasive diagnostic method that allows you to identify disorders of the pelvis system in the event of the formation of a tumor, cyst, or stones. If the clinical picture is unclear, a biopsy will be required.
Radionuclide research– one of the most important for determining pathology at the earliest stage. It is used in cases where diagnosis by other methods does not provide a clear picture. Ease of use, the ability to carry out repeated studies without harm to the patient, as well as the ability to perform tests in the presence of an allergy to contrast agents, have made the diagnostic method one of the most commonly used. The advantages are also considered to be the ability to determine the total work performed by the kidneys, as well as evaluate them individually. However, the nurse must be able to correctly install the sensors, since the slightest malfunction will lead to erroneous readings.

Important! The role of medical personnel in this version of the study is great, since the method is often used repeatedly throughout the course of treatment to assess the effectiveness of therapy and the need for immediate changes in treatment

MRI, CT are methods for studying renal pathology, which provide the most complete and clear picture of the dynamics of the disease, possible uncharacteristic changes in organs, the presence and size of tumors and other indications. The methods are complementary and extremely important when a diagnosis of renal failure is suspected. A slight negative effect in patients is the need to lie motionless and constant background noise during MRI, but the examination is considered one of the most informative and should not be abandoned.

Which diagnostic and research method the doctor chooses depends on many reasons. Often, kidney pathologies are only a background disease; it is necessary to find the underlying disease and identify the determining factor of the ailment that has arisen, and here all means are good.

If a person has “bags” under the eyes, and the skin becomes gray and dry, it means that there is a malfunction in the urinary system. You should not postpone a visit to a specialist to examine the kidneys and adrenal glands, as well as assess their functional activity.

A urologist or nephrologist will tell you how to check your kidneys. During the diagnosis, severe complications can be avoided. Treatment at an early stage of any disease allows you to quickly achieve the desired results and avoid unwanted surgical intervention.

When to go to the doctor

It is rare to meet a person who regularly undergoes a complete examination of the body. Most people put off visiting a doctor, swallow handfuls of pills and convince themselves that the pain, stinging, and tingling will soon disappear. And only when symptoms worsen do they make an appointment. This tactic is extremely dangerous, especially when the kidneys hurt.

Paired organs rid the blood of waste and toxins, regulate blood pressure, and take part in metabolism. Even a slight disruption in their work will quickly affect the functioning of all life systems.

Modern methods for diagnosing kidneys are painless and do not cause any discomfort to a person. People with the following types of kidney damage should definitely undergo an examination procedure:

high blood pressure;
frequent night urination;
decrease in the volume of urine excreted;
pain in the lower abdomen and lumbar region;
increased body temperature;
burning and stinging when emptying the bladder;
change in the color and smell of urine.

A kidney examination should not be postponed if even one of the above-described symptoms of malfunction of the urinary system appears. Experts recommend conducting a thorough diagnosis of paired organs twice a year.

It is important for people with congenital or acquired kidney pathologies to undergo a complete medical examination. If there is a hereditary predisposition to urolithiasis or glomerulonephritis, it is necessary to regularly examine the child from infancy.

If you experience nagging pain in your side, you should check your kidney function.

Diagnosis at home

It is not possible to conduct a full kidney check at home. But if you suspect a disruption in their functioning, you should determine the area where the pain is localized and try to analyze your sensations:

sharp, acute spasms indicate a rapidly developing inflammatory process in the structural elements of the kidneys (calyces, pelvis, parenchyma, tubules);
nagging, aching pains that appear during hypothermia or eating spicy foods occur with sluggish chronic pathologies.

You can also check your urine at home for foreign impurities. To do this, you need to collect urine in a transparent container and carefully examine it. If fresh blood, dark blood clots, flakes, or cheesy sediment are detected, you must make an appointment for a consultation with a urologist.

A 24-hour urine test will help evaluate your kidney function. Within 24 hours, you need to collect urine in a calibrated container, and then measure the resulting volume. If it does not exceed 1.5-1.8 liters, then the kidneys have lost the ability to fully filter blood and secrete urine. A significant volume (more than 2.5 liters) means that the urine contains little uric acid and its compounds, waste products and protein breakdown products. The kidneys cannot fully concentrate urine, which causes serious damage to the entire body.

Kidneys should be examined if urine color changes

What tests are the most informative?

After conducting an external examination of the patient and listening to his complaints, the urologist will tell you where to start the examination and what tests are necessary. As a rule, the results of laboratory and biochemical tests of urine and blood are needed to make an initial diagnosis. The content of white and red blood cells, as well as epithelial tissues, is determined in urine. The clarity, color and specific gravity of urine must be assessed. The concentration of casts, proteins and glucose is a determining factor in the presence of an infectious focus in the kidneys.

An informative method for studying the functioning of paired organs is the daily volume of urine. It is necessary to submit to the laboratory urine collected during the day, excluding the first emptying of the bladder. In this way, it is possible not only to establish the presence of an inflammatory focus, but also the location of its localization in one of the organs of the urinary system.

In order to determine the type of pathogenic pathogen, laboratory technicians inoculate a biological sample in a nutrient medium. This method reveals the sensitivity of microorganisms to antibacterial drugs that will be used in treatment.

from a finger to establish or refute the inflammatory process and the extent of its spread;
from a vein to determine the concentration of proteins and urea.

For reliable test results, you must not eat food 12 hours before the procedure. If you suspect an endocrine etiology of decreased functional activity of the kidneys, you should not drink any liquid or even brush your teeth. People with systemic diseases need laboratory tests every 6 months.

Modern diagnostic methods

After studying and evaluating the results of laboratory tests, it is necessary to examine the kidneys to determine the extent of their damage. The doctor chooses diagnostic methods depending on the patient’s age and the expected disease. Research methods that use radiation are strictly prohibited for pregnant women.

Computed tomography is used to examine the kidneys.

Such informative examination procedures as computed tomography and magnetic resonance imaging are not prescribed for young children and people with mental pathologies. During the kidney check, it is necessary to remain completely still for an hour, which these categories of patients are incapable of. The following studies are usually carried out at varying levels of complexity:

ultrasonography. The procedure allows you to assess the condition of the calyces, pelvis and tubules, differentiate between benign and malignant neoplasms, and determine the localization of the infectious focus. The study allows you to detect stones in the kidneys or bladder and suggest them chemical composition. This is the only diagnostic method that has no contraindications and does not require special preparation;
urography. The method is indispensable for establishing the degree of damage to the kidney vessels and assessing the blood supply to the organs of the urinary system. Before the procedure, patients are injected with a contrast agent. After it spreads through the veins, arteries and capillaries, the smallest vessels are visualized on the computer screen. Urography is contraindicated for people who have individual sensitivity to contrast agents;
X-ray examination. During the procedure, the human body receives a dose of radiation that is considered safe. The photographs are not always informative, since the images are obtained only in one or two projections;
scintigraphy. The static method allows you to determine the shape of the kidneys, their location relative to each other, and assess the degree of damage to the pelvis and calyces. During dynamic scintigraphy, patients are injected with a contrast agent. On the monitor screen, the specialist monitors the movement of blood through the pelvic vessels in real time, checks the integrity of the veins, arteries and capillaries;
Magnetic resonance imaging. The procedure is contraindicated for patients with pacemakers, metal dental implants, and even tattoos. There are also some restrictions for pregnant and breastfeeding women. Modern diagnostic techniques make it possible to obtain three-dimensional images of the kidneys and evaluate the functioning of a single kidney after removal of the other. After completing the study, the patient receives a transcript of the results within 15-20 minutes;
CT scan. This diagnostic method is used to study possible kidney damage. structural elements, assessing the effectiveness of prescribed treatment, determining the area of surgical intervention. Using CT, you can evaluate the condition of the kidney before making a decision to remove the second one.

When examining the kidneys, the urologist always examines the bladder using cystoscopy. To do this, a thin catheter with a built-in camera is inserted into the hollow organ, and the diagnostic results are visualized on a computer screen.

Cystoscopy is an auxiliary method for recognizing a decrease in the functional activity of the kidneys. If blood or pus is found in the urine, then it is necessary to determine the location of the inflammatory focus.

Ultrasound is an effective method for checking the kidneys

Many modern methods diagnostics are contraindicated or are of little information for some patients (pregnant women, people with prostheses containing metal). Using endoscopic techniques, the urethra and bladder are examined. By installing the built-in camera so that the opening of the ureters is in the field of view, you can find out whether the kidney is bleeding.

After all laboratory and instrumental studies have been completed, a biopsy sometimes becomes necessary.

This morphological diagnostic method is used to differentiate malignant and benign neoplasms of the kidneys, liver, and lungs. Using a special endoscopic instrument, a small piece of the biological sample is pinched off for further examination in the laboratory.

For those people who care about their health, unexpected diagnoses are not scary. They undergo all examinations on time and immediately make an appointment with a doctor if their general condition worsens or if pathological signs of inflammation appear. Diagnosing kidney disease at an early stage allows you to avoid long-term hospital treatment.