RU2649125C1 - Method for determining the risk of calciinate development in case of cystic of kidney diseases of children - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention refers to medicine, namely to nephrology and urology, and can be used in order to predict complications of polycystic kidney disease that increase the severity of the disease, in particular, to predict the formation of calcifications in the cysts of the kidneys. Citrate-creatinine index is calculated according to the following formula in order to determine the risk of development of calcifications in children with polycystic kidney disease in urine, determine the daily excretion of citrates and creatinine: N=C/K, where N is the citrate-creatinine index; C – daily excretion of citrates, mmol/l; K – creatinine content in urine, mmol/l and at N less than 0.3 the risk of calcification in the kidney cysts is defined as high.

EFFECT: technical result consists in the reliable prediction of the development of calcification in polycystic kidney disease by means of examining the biochemical components of urine, which allows to timely start the appropriate therapy, including the appointment of citrate-containing drugs.

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Description

The invention relates to medicine, namely to nephrology, urology, and can be used in predicting complications of polycystic kidney disease, increasing the severity of the disease, in particular to predicting the formation of calcifications in kidney cysts in children.

Polycystic kidney disease is a genetic disease manifested by cystic degeneration of the renal parenchyma, one of the common manifestations of which is autosomal dominant polycystic kidney disease.

The urgency of the problem lies in the fact that in the structure of the causes of terminal chronic renal failure (CRF) in adult patients, polycystic kidney disease takes fourth place and an average of 6-10%.

The appearance of multiple cysts at an early age is considered as a prognostically unfavorable factor due to the higher rate of disease progression. Moreover, the prevalence of urolithiasis among patients with multiple cysts is 5-10 times higher than in the general population, and the prevalence of urolithiasis, in particular, with autosomal dominant polycystic kidney disease in childhood and adolescence reaches 20-36%, and 40 years already 60%.

Serious complications that occur in children with polycystic kidney disease due to the development of nephrocalcinosis and urolithiasis include urinary tract infections, tubulointerstitial nephritis, hydronephrosis, nephrosclerosis, which ultimately not only significantly impairs the quality of life, but also leads to more rapid progression of chronic kidney disease and chronic renal failure.

The main effect of citrate is the chelation of calcium ions in the urine, which occurs at a molar ratio of 4: 1, while citrate creates strong but soluble complexes with calcium, thereby effectively reducing the concentration of free Ca ⁺⁺ ions in the urine. A decrease in Ca ⁺⁺ in the urine decreases the crystallization rate of oxalate and calcium phosphate.

Among the causes of hypocitraturia, the most common are the use of thiazide diuretics, carbonic anhydrase inhibitors, magnesium deficiency, acidosis, as well as impaired transmembrane transport of citrates, decreased mitochondrial function, however, in most cases, the causes of low citrate levels are currently not clear.

The determination of citrates, as well as the determination of most biochemical indicators of human metabolism, has undergone a certain evolution of methods, from manual titration with visual control of the citrates and its derivatives to capillary electrophoresis and various types of chromatography, including high performance liquid chromatography.

Most studies consider only the possibility of determining a quantitative or semi-quantitative amount of urine citrate in patients without identifying possible risks of complications and the progression of diseases, such as nephrocalcinosis and urolithiasis [Dutov V.V. Dissolution of kidney stones: to whom? when? as? Medical advice. 2016. No9. S. 84-90; Yarovoy S.K., Moskaleva N.G., Maksudov P.P. Drug therapy for metabolic bone skeleton lesions in urolithiasis. Experimental and clinical urology. 2014. No2. S. 88-93; Goloshchapov E.T., Glazunova E.V., Savenkova T.A. Prevention of stone formation with bilateral recurrent nephrolithiasis. Nephrology. 2008.V. 12. No. 3. S. 89-94; Kogan M.I., Khasigov A.V., Belousov I.I. Features of mineral metabolic changes in blood and urine in patients with coral nephrolithiasis in the southern region of Russia. Medical Bulletin of Bashkortostan. 2012.V. 7. №1. S. 56-59; Kustov A.V., Strelnikov A.I., Ayrapetyan A.O., Moryganov M.A., Zhuravleva N.I. Diagnosis of metabolic disorders and metaphylaxis of recurrent calcium-oxalate urolithiasis. Urology. 2015. No5. S. 86-88].

In this case, the diagnostics usually used the techniques developed in the first half of the 20th century, when sophisticated hardware was not required to determine citrates. However, they included numerous manipulations with a large number of reagents, including precursors such as sulfuric acid, potassium permanganate, chloroform, organic solvents such as methanol and petroleum ether, centrifugation and filtration stages of intermediate products, washing of the precipitate. A number of working solutions required the preparation of Ex-tempora. Multi-stage and labor-intensive did not contribute to the high sensitivity of the study.

The results obtained by these methods were significantly affected by the quality of the reagents and the quality of the preparation of working reagents. In addition, they were sensitive to concomitant substances contained in the studied samples, which limited their specificity [Alyaev Yu.G., Kuzmicheva GM, Rapoport L.M., Rudenko V.I. Modern aspects of citrate therapy in patients with urolithiasis. Medical class. 2004; 4: 20-24; Golovanova O.A. Pathogenic mineral formation in the human body. News of Tomsk Polytechnic University. 2009; 315 (3): 51-56].

However, in the prior art there is no information on determining the risk of developing and predicting the course of nephrocalcinosis and urolithiasis in patients with various nephrological pathologies, including patients with nephrocalcinosis with polycystic kidney disease.

There are currently no published data on such images where the task of predicting (determining) the high risk of calcifications in children would be solved.

The problem solved by the present invention is to identify an objective indicator of a high risk of calcification in polycystic kidney disease in children.

The technical result consists in reliable prediction of the development of calcifications in polycystic kidney disease by studying the biochemical components of urine, which allows you to start the appropriate therapy in time, including the appointment of citrate-containing drugs.

We have identified an objective prognostic indicator that allows us to determine the high risk of calcifications in case of polycystic kidney disease by the level of citrates and the content of creatinine in the urine.

The invention consists in the following.

To determine the risk of calcification in polycystic kidney disease in urine, the daily excretion of citrates and creatinine are determined. The citrate-creatinine index is calculated by the formula:

N = C / K,

Where

N — citrate creatinine index;

C - daily excretion of citrates, mmol / l;

K - urine creatinine content, mmol / l.

When N is less than 0.3, the risk of calcification in kidney cysts is defined as high.

Daily urinary citrate excretion can be determined by enzymatic method.

The method is as follows.

Daily urine for research is collected and stored in a cool place (refrigerator), its daily amount is determined and an aliquot of urine is used after it is released from cellular detritus, blood cells, and crystals by centrifugation.

To determine the excretion of citrates in urine collected per day in children with various forms and severity of polycystic kidney disease, domestic kits for determining citrates in biological fluids “Photocitrates” can be used.

Methods for the determination of creatinine in urine are known in the art.

Determination of creatinine is carried out using a photometric colorimetric test for kinetic measurements (HUMAN, Germany). The principle of the method is based on the fact that in an alkaline solution, creatinine forms a complex of orange-red color with picric acid, the absorption of the complex is proportional to the concentration of creatinine in the sample. Reagents: 1) a solution of sodium hydroxide (1.6 mmol / l) is diluted with distilled water in a ratio of 1: 4; 2) prepare a working solution of picric acid (26 mmol / l) and the resulting sodium hydroxide solution in a ratio of 1: 1 - working solution. 1000 μl of the working solution is added to 100 μl of the sample (standard) and the absorbance is measured after 30 seconds (A1) and after 2 minutes (A2) at a wavelength of 492 nm A2-A1 = ΔA of the sample (standard). The concentration of creatinine in the urine is determined by the formula:

Δ Standard / Δ Standard × 88.402 = mmol / L.

The enzymatic method for the determination of citrates is as follows.

The determination of citrates is carried out using a set of "Photocitrates" (LLC "IMPACT") to determine citrates in the urine by the enzymatic method. The principle of the method is based on the fact that the enzymatic hydrolysis of citric acid in the presence of the citrate lyase enzyme proceeds to the formation of oxaloacetic acid, followed by decarboxylation of it to pyruvic acid and reduction of the formed acids under the action of reduced NADH in the presence of L-malate dehydrogenase (MDH) and L-lactase dehydrogen LDH) to L-malic and L-lactic acids. In this case, NADH is transformed into the oxidized form of NAD +. The decrease in the concentration of NADH in the test solution is proportional to the concentration of citric acid or its salt. The change in optical density is measured at a wavelength of 340 nm.

The kit includes reagents:

1) Glycylglycine buffer, OD mol / L, pH 7.8.

2) Suspension of enzymes - MDH = 600 units / ml, LDH + 1400 units / ml.

3) NADH 0.1 mmol / ml.

4) The enzyme citrate lyase 40 u / ml

5) Calibrator (citric acid solution 1.04 mmol / L).

For analysis, 0.1 ml of daily urine is used. To the sample add 1.0 ml of reagent 1; 0.02 ml of reagent 2; 0.05 ml of reagent 3; 0.1 ml of distilled water. After 2 minutes, absorbance (A1) was measured. Add 0.1 ml of reagent 4 and measure the optical density after 3 minutes (A2). For the calculation, the differences in the optical densities of the blank, calibration sample and sample are used.

C = Δ Sample / Δ Caliber. samples × 1.04 × F = mmol / L,

where: F is the dilution factor of the sample,

1.04 - the concentration of citric acid in the calibrator, mmol / L.

The amount of citrate in daily urine: C (mmol / L) × daily urine volume.

The results of a biochemical study are used to calculate the total amount of citrates excreted in the urine per day, as well as in terms of mmol creatinine (citrate / creatinine index mmol citrate / mmol creatinine).

To prove the possibility of realizing the claimed purpose and achieving the specified technical result, we provide the following data.

Clinical examples.

Clinical example 1.

Boy A., 16 years old, is observed at the Nephrology Department of the NIKI Pediatrics named after Academician Yu.E. Veltishcheva with a diagnosis of Autosomal dominant polycystic disease (cysts of the kidneys, liver). CKD II Art.

From the anamnesis it is known: heredity is burdened by paternal polycystosis (polycystic kidney disease in a brother and two father sisters), the father was not examined. The boy from the first pregnancy, urgent delivery, weighing 3190, height 52 cm. Development by age. An examination by a surgeon regarding lymphostasis of the scrotum and left lower limb during ultrasound revealed polycystic kidney disease. Observed in the Department of Nephrology since 2014. He regularly takes Enap at 7.5 mg per day. On examination, the condition upon receipt of moderate severity. She feels well. The skin is clean. The pharynx is dim. Vesicular breathing. Heart sounds are rhythmic, distinct. HELL 125/65 mm Hg The abdomen is soft, painless. Urination is free. Weight 55 kg, height 166 cm. During examination, clinical analysis of blood and urine without features (urine PH 5.0-6.0). The main indicators of a biochemical analysis of blood within the reference values, electrolytes are normal, creatinine is 101 μmol / L, the estimated glomerular filtration rate (rSCF) is 91 ml per minute on 1.73 of the body surface. In the biochemical analysis of urine, excretion of oxalates, urates, calcium and phosphorus is within normal limits, including urine creatinine conversion. ECG - Sinus rhythm with a tendency to tachycardia, heart rate 84-107 beats. in minutes The vertical position of the EOS. Violation of intraventricular conduction.

With ultrasound of the kidneys and internal organs, polycystic disease (multiple cysts of the liver, kidneys). In the parenchyma of both kidneys, there are multiple: 1) cysts, simple and multi-chamber, with the maximum sizes: 1.4 × 1.8 cm on the right, 2.6 × 3.1 cm on the left, fine suspension in large cysts, in the parenchyma and single cysts - calcifications up to 0.5 cm; 2) paired linear signals of increased echogenicity (walls of small cysts). Diffuse changes in the renal parenchyma. Enlarged left kidney.

In the study of urine citrates, a result of 0.34 mmol / L was obtained at a normal rate (0.6-1.67), urine creatinine 8.1 mmol / L, citrate-creatinine index 0.04.

Thus, in a child with autosomal dominant polycystic kidney disease, there were multiple calcifications in the kidney cysts and an isolated decrease in urine citrate, while the citrate-creatinine index was 0.04, which is a high risk for the formation and progression of calcification in kidney cysts and can lead to an increase in calcifications in kidney cysts and causes the early inclusion of citrate-containing drugs in the treatment of disease.

Clinical example 2.

Boy D., 2 years old. The child is observed in the Department of Nephrology with autosomal dominant polycystic kidney disease (ADPBP). A child from a family with a family history of ADPBP is with his mother (first diagnosed with ultrasound of the kidneys at the age of 11 years), with his grandfather by l / mother. From 1 pregnancy proceeding with gestosis in 1/3, from 1 physiological birth at 38 weeks. Kidney cysts were detected by ultrasound during antenatal development. At the age of 2 years, urinary analysis revealed microproteinuria up to 0.2 g / l of an intermittent nature. Entered for an initial nephrological examination and clarification of further management tactics. On admission: growth - 92 cm (75 percentile), weight - 13 kg (50 percentile) - harmonious development. The state of health is satisfactory. The skin and visible mucous membranes are clean, pronounced venous network in the nose. Free breathing through the nose. Pharynx - not hyperemic, tonsil hypertrophy. Auscultatory - vesicular breathing in the lungs, no wheezing. Heart sounds are sonorous, rhythmic. HELL 90/60 mm Hg Heart rate 82 beats. in minutes The abdomen is soft, painless. The liver is palpated at the edge of the costal arch. No swelling. Diuresis is sufficient. Pasternatsky’s symptom is negative. Urination is not impaired. There are no dysuric phenomena.

When examining a clinical analysis of blood and urine without features (urine pH 5.5-6.5). The main indicators of a biochemical analysis of blood within the reference values, electrolytes are normal, creatinine 45 μmol / l. In the biochemical analysis of urine, excretion of oxalates, urates, calcium and phosphorus is within normal limits, including urine creatinine conversion. ECG - a small delta wave in II III avF holes Conclusion: moderate sinus arrhythmia, heart rate = 111-92 beats. in 1 min. The normal position of the EOS. Standing - without significant dynamics.

With kidney ultrasound: the kidneys are located in a typical place. Renal mobility is within normal limits. The contour is uneven. Dimensions right 6.6 × 4.1 × 2.9 cm; volume 41.9 cm ³ ; left 7.0 × 4.4 × 3.0 cm; volume 48.0 cm ³ . The ratio of kidney volume and body weight 0.69% normal (0.4-0.6)% (the ratio is unreliable due to lack of body weight). The parenchyma is not clearly differentiated, thickened, echogenicity is increased (higher than the echogenicity of the liver); with CDK - blood flow to the kidney capsule, on the right - an aberrant artery to the upper pole of the kidney, on the left - an aberrant artery to the upper pole of the kidney. In the renal parenchyma: multiple cysts, maximum sizes: on the right - 1.0 × 1.1 cm, on the left - 0.6 × 0.8 cm; paired linear signals of increased echogenicity (walls of small cysts). The central echo complex is not clearly structured. The pelvis is not expanded, the upper group of calyxes is 0.3 cm on the left.

In the study of urine citrates, the result was 0.68 mmol / L (0.6-1.67), urine creatinine 3.2 mmol / L, citrate-creatinine index 0.21. A decrease in the level of citrate-creatinine index of less than 0.3 made it possible to attribute the child to a high risk group for the development of nephrocalcinosis, which was confirmed by dynamic observation.

When observed in follow-up after 1 year during the follow-up examination of the ultrasound of the kidneys in the child, parietal calcifications (up to 0.2 cm) and single small paired linear echo signals of increased echogenicity were noted. Pyramids of increased echogenicity are heterogeneous due to multiple point hyperechoic inclusions up to 0.3 cm. Thus, in a child with polycystic kidney disease with a normal level of urine citrates, but with a citrate-creatinine index less than N <0.3, single calcites appear in the cysts, which determines high risk of nephrocalcinosis and early inclusion of citrate-containing drugs in the treatment of disease.

Clinical example 3.

Boy M., 4 years old, is observed in the Nephrology Department of the NIKI Pediatrics named after Academician Yu.E. Veltishchev with a diagnosis of ADPP, CKD 1 tbsp.

From the anamnesis it is known: a child from a family with a burdened family history of ADPBP. A child from 2 pregnancies with a threat of abortion, from 1 physiological birth at 37 weeks. Kidney cysts were detected at the first screening at the age of 1 year. The skin and visible mucous membranes are clean, pronounced venous network in the nose. Free breathing through the nose. Pharynx - not hyperemic, tonsil hypertrophy. Auscultatory - vesicular breathing in the lungs, no wheezing. Heart sounds are sonorous, rhythmic. Heart rate 90 beats. in minutes The abdomen is soft, painless. The liver is palpated at the edge of the costal arch. No swelling. Diuresis is sufficient. Pasternatsky’s symptom is negative. Urination is not impaired. There are no dysuric phenomena.

During the examination, a clinical analysis of blood and urine without features (urine PH 6.0-6.5). The main indicators of a biochemical analysis of blood within the reference values, electrolytes are normal, creatinine is 44 μmol / l. In the biochemical analysis of urine, excretion of oxalates, urates, calcium and phosphorus is within normal limits, including urine creatinine conversion.

Ultrasound of the kidneys Ultrasound picture of polycystic kidney disease in an autosomal dominant manner. Diffuse changes in the renal parenchyma. The parenchyma is not clearly differentiated, thickened, echogenicity is increased (higher than the echogenicity of the liver); with CDK - blood flow to the kidney capsule, on the right - an aberrant artery to the upper pole of the kidney, on the left - an aberrant artery to the upper pole of the kidney. In the renal parenchyma: multiple cysts, maximum sizes: on the right - 1.0 × 1.1 cm, on the left - 0.6 × 0.8 cm; paired linear signals of increased echogenicity (walls of small cysts).

In the study of urine citrates, the result was 1.3 mmol / L (0.6-1.67), urine creatinine 1.5 mmol / L, citrate-creatinine index 0.8. In a child with a normal level of urine citrates and a citrate-creatinine index of 0.8, there is a lack of calcifications in the kidney cysts. The normal value of the citrate-creatinine index determines a low risk of calcification, which is noted during further dynamic observation. In case of follow-up, after a year the condition is without negative dynamics.

The proposed method was used in 20 children with polycystic kidney disease aged 3 to 17 years (9.31 ± 4.46 years), including 7 girls (35%) and 13 boys (65%). After renal ultrasound, they did not have data on the presence of calcites, exacerbation of infections of the urinary system over the past 3 months, there were no signs of decompensated endocrine, metabolic liver, cardiovascular, hematological, and renal pathologies.

As a result of a study conducted in accordance with the proposed method, 85% of children had a high risk of developing calcifications in kidney cysts, which was then confirmed by ultrasound.

The specificity of the method is 85%, and the sensitivity is 84%.

Claims (8)

1. A method for determining the risk of calcifications in children with polycystic kidney disease, in which urine daily excretion of citrates and creatinine are determined in urine, the citrate-creatinine index is calculated by the formula: N = C / K, Where N — citrate creatinine index; C - daily excretion of citrates, mmol / l; K - urine creatinine content, mmol / l; and when N is less than 0.3, the risk of calcification in kidney cysts is defined as high. 2. The method according to p. 1, characterized in that the daily excretion of citrates in the urine is determined by the enzymatic method.