RU2216733C2 - Method for detecting renal functional capacities - Google Patents

Abstract

FIELD: medicine, nephrology. SUBSTANCE: the present method deals with clinical and experimental trials to detect excretory renal capacity by urinary concentration of D-xylose collected per two 1-hlong periods; as for concentration renal capacity it is determined by concentration index calculated by the ratio of D-xylose concentration/ml urine collected per the first 1-h-long period to D-xylose concentration/ml blood taken 5 min after intravenous injection of D- xylose. The present innovation enables to provide earlier diagnostics of disorders in concentration and excretory renal functions. EFFECT: higher efficiency. 1 ex

Description

 The invention relates to medicine, namely nephrology, urology, is used in clinical and experimental studies, where it is necessary to determine the excretory and concentration ability of the kidneys.

 There are several methods for determining the excretory ability of the kidneys, based on the excretion of inulin, urea, endogenous creatinine. Concentration ability for specific gravity of urine (Nephrology. Guide for doctors, Tareeva I.E., 1995; Nephrology in therapeutic practice, Chizh A.S., 1994).

 The inulin method for determining the excretory ability of the kidneys has several disadvantages: the substance itself is not exponentially excreted by the kidneys, it does not dissolve well in water, and in renal failure it is not always allocated adequately to the degree of kidney damage; the method requires: prolonged intravenous drip to ensure constancy of the level of inulin in the blood, catheterization of the bladder.

The method for determining urea excretion also has a number of significant disadvantages:
- From 40 to 60% of urea is reabsorbed in the renal tubules;
- the level of urea excretion depends on the amount of urine output;
- the concentration of urea in the blood is dependent on the intake of protein with food.

A number of significant drawbacks has the approach to determining the concentration ability of the kidneys:
- the data obtained in the calculations are relatively indicative;
- the relative density of urine is affected by the content of protein and sugar;
- it is difficult to obtain clear quantitative characteristics of the state of the concentration ability of the kidneys.

 Prototype: A method for determining endogenous creatinine (Reberg test) is widely used in the clinic and makes it possible to more accurately determine the state of renal excretory ability (Chizh A. Nephrology in therapeutic practice, 1994). It is closest to our proposed method for its final results, therefore, taken as a prototype.

Этот способ имеет ряд существенных недостатков:
- необходимость водной нагрузки, которая может явиться отрицательным фактором при отеках и ограничении выделительной способности почек;
- недостаточная точность и специфичность пробы, обусловленная тем, что при определении креатинина в плазме выделяется не только креатинин, но и креатининоподобные хромогены;
- малонадежность пробы при низком диурезе;
- выделение до 40% креатинина путем секреции при патологии (нефротическом синдроме), приводит к более высокой концентрации его в моче по сравнению с должной.The prototype study is carried out on an empty stomach, give drink 500 ml of water for one hour. A urine sample is collected for control. Then, every half hour, blood is taken from a vein. The first and second portions of urine are collected in two separate vessels. After calculating the minute diuresis and determining the concentration of creatinine in the urine and blood, the clearance is calculated by the formula

This method has several significant disadvantages:
- the need for water load, which may be a negative factor in edema and restriction of the excretory ability of the kidneys;
- lack of accuracy and specificity of the sample, due to the fact that when determining creatinine in plasma, not only creatinine is released, but also creatinine-like chromogens;
- unreliability of the sample with low diuresis;
- the allocation of up to 40% creatinine by secretion in pathology (nephrotic syndrome), leads to a higher concentration of it in the urine compared to the due.

 The aim of the invention is to improve the early diagnosis of impaired concentration and excretory ability of the kidneys.

The invention:
It consists in the fact that the concentration of d-xylose in the blood is proportional to its excretion in the urine, which makes it possible to determine the excretory and concentration ability of the kidneys in one study. Excretory ability according to the concentration of d-xylose in urine collected over two one-hour periods. The concentration ability of the kidneys is according to the concentration index of d-xylose, i.e., the ratio of the concentration of d-xylose in 1 ml of urine (collected during the first one-hour period) to its concentration in 1 ml of blood taken 5 minutes after intravenous administration of d-xylose (primary urine).

 The proposed method is as follows: before the introduction of a solution of d-xylose empty the bladder, take 3-4 ml of urine for control. A control blood sample is taken at the same time. After this, a 20% sterile solution of d-xylose is administered intravenously at the rate of 125 mg per kg of body weight. 5 minutes after iv administration, 0.3 ml of blood is taken, and urine is collected in two one-hour intervals. The concentration of d-xylose in urine and blood is determined by the micromethod developed by Hasanova P.O. and Shamov I.A. (02930 certificate of industry value).

 D-xylose after intravenous administration after 3-5 minutes is maximally concentrated in the blood and with normal excretory ability of the kidneys, its concentration is allocated in this period of time, while the rate of excretion is constant. Therefore, the excretory ability of the kidneys is judged by its excretion in urine collected over two one-hour periods. Normally, during this period, from 50-70% of the iv dose is allocated.

 The concentration ability of the kidneys is determined by the concentration index, according to the formula U / P, where U is the concentration of d-xylose in 1 ml of urine collected during the first one-hour period, and P is the concentration of d-xylose in the blood 5 minutes after intravenous administration. The concentration index of d-xylose is 32-40. Since d-xylose is a low molecular weight carbohydrate, it is not found in the free form in the body and does not combine with proteins, it is well excreted by the kidneys, its concentration in the blood corresponds to the concentration in primary urine. Thus, the concentration index of d-xylose shows how many times the primary urine is concentrated relative to the final.

 With a decrease in the excretion rate of d-xylose, respectively, less of it is excreted in the urine and xylosemia lasts longer, therefore, the concentration index decreases, respectively, according to the severity of the pathological process. Thus, the proposed method allows one study to determine the excretory and concentration abilities of the kidneys. Excretory ability - by the concentration of d-xylose in urine collected over two one-hour periods. Concentration ability by concentration index, i.e. the ratio of the concentration of d-xylose in 1 ml of urine collected during the first one-hour period and the concentration of d-xylose in the blood taken 5 minutes after intravenous administration.

 Since the intravenous administration of the d-xylose solution has not been formally introduced into the pharmacopeia, the new method has been tested on animals - dogs - so that after the introduction of this method into the pharmacopeia, the study should be carried out in humans.

 An example of a specific implementation. As an example of a specific implementation, studies conducted on dogs were taken. The studies were carried out in three stages: the control period - before giving anesthesia, the period after anesthesia and after complete transverse transection of the spinal cord. The functional state of the kidneys was judged by a general analysis of urine, creatinine and blood urea. As an example, we give a study conducted on a dog weighing 8 kg (Laboratory journal, experimental protocols from 01.20.2000, 01.25.2000, 02.02.2000, 02.13.2000, 02.25.2000, 5 ml of a 20% solution of d-xylose was intravenously administered) . Control period; general urine analysis: straw yellow color, no protein, specific gravity 1025, white blood cells 0-1, no red blood cells, blood creatinine 86.3 μmol / l, urea 8.2 mmol / l, endogenous creatinine clearance 82 ml / min. In two hours, d-xylose stood out - 60% (38% in the first hour, 22% in the second hour) of the intravenous dose, concentration index 36.

 Studies conducted after giving anesthesia, thiopental sodium at the rate of 40 mg per kg of weight. Urinalysis: color straw yellow, protein 0.3 g / l, specific gravity 1020, white blood cells 4-6, red blood cells 8-10, blood creatinine 90.2 μmol / l, urea 9.3 mmol / l, endogenous clearance creatinine 73 ml / min. Within two hours of d-xylose, it stood out - 42% (in the first hour 24%, in the second hour 18%) of the intravenous dose, the concentration index is 26. In this case, a slight decrease in the excretory ability of the clearance of endogenous creatinine and a decrease in the excretion of d-xylose are determined with urine, a decrease in the specific gravity of the urine and concentration index.

 Studies conducted after 10 days showed that these data are within the control digits, i.e. the process is reversible. Subsequently, the same dog underwent a complete transverse transection of the spinal cord at the level of Th7-Th8. Urinalysis: color of meat slops, protein 0.9 g / l, specific gravity 1015, white blood cells 8-10, red blood cells - large numbers, blood creatinine 156.0 mmol / l, urea 10.9 mmol / l, clearance of endogenous creatinine 64 ml / min. In two hours, d-xylose stood out - 34% (for the first hour 18%, for the second hour 16%) of the intravenous dose, concentration index 20. In subsequent studies, a further decrease in the clearance of endogenous creatinine to 55 ml / min was noted, in two hours 30% (15% for the first hour and 15% for the second hour) from the intravenously administered dose were allocated; concentration index decreased to 16.

 An analysis of the studies shows that after a complete transverse transection of the spinal cord in the next 10-15 days, there is no restoration of the excretory and concentration ability of the kidneys, but on the contrary, a further decrease in these functions occurs. The data obtained by known methods and the method we propose correspond and adequately reflect the state of the described functions in normal and pathological conditions.

Distinctive features of the proposed method from the prototype:
1. In the prototype, a water load is required, the proposed method does not require a water load and is carried out in physiological conditions for the body.

 2. In the prototype, the sample is not sufficiently accurate and specific, since when determining creatinine in plasma, not only creatinine is released, but also creatinine-like chromogen; the micromethod for determination of d-xylose in the blood is highly specific and readily available.

 3. Conducting samples according to the prototype is unreliable with low diuresis, the results obtained by the proposed method are independent of diuresis.

 4. In the prototype, the excretory ability is judged by the purification of plasma from endogenous creatinine, which is formed during muscle work and can increase with the breakdown of muscle fibers. The proposed method makes it possible to determine the excretory ability of the excretion of d-xyllose, which is not contained in a free form, is a low molecular weight carbohydrate, is excreted only by the kidneys and meets all the requirements of a pharmacopeia for substances used to determine the excretory ability of the kidneys.

 5. The data obtained from the prototype, the determination of concentration ability are relative, and the proposed method allows to obtain a quantitative characteristic.

 6. According to the prototype, the excretory and concentration ability is determined by two different studies, and according to the proposed method, a quantitative characteristic is obtained by one study after iv administration of a sterile solution of d-xylose.

 Positive effect: the method is informative, accessible. After the introduction of the intravenous method of introducing a solution of d-xylose into the State Pharmacopoeia, it can be widely used for early detection of violations of the excretory and concentration ability of the kidneys. This is of great medical and social importance not only in connection with the frequency of their disease, but also with some features. More than 60% of renal patients are under the age of 40, the most active age. By their nature and course, these diseases proceed latently - latently and are detected in the terminal stage and therefore are difficult to treat (Majdrakov M.G., Popov N.G. Kidney diseases, 1976).

 By the proposed method, you can get information about quantitative data on the limitation of excretory and concentration ability of the kidneys. This will make it possible to identify violations of these functions in the early stages of the disease, when other known methods do not succeed. Hence the opportunity to start treatment in the early periods of the disease, which is an important factor for the full recovery of patients. There is an opportunity in the dynamics to observe the change in these functions in the treatment of renal patients. This method can be applied to monitor the state of the functional ability of the kidneys during hemodialysis (before and after).

Claims (1)

 A method for determining the functional ability of the kidneys, which consists in the intravenous administration of D-xylose and the study of the concentration of D-xylose in the blood and urine, characterized in that the excretory ability of the kidneys is determined by the concentration of D-xylose in the urine collected over 2 one-hour periods, and the concentration ability of the kidneys determined by the concentration index determined by the ratio of the concentration of D-xylose in 1 ml of urine collected during the first one hour period to the concentration of D-xylose in 1 ml of blood taken 5 minutes after intravenous administration of D-xylose.