Investigation of the functional ability of the kidneys

The simplest method tests the total renal function is by measuring the amount of urine and its specific weight. Due to the fact that during the day the amount of urine may vary depending on the amount of fluid you drink, the food regime, air temperature, sweating, and so on, should measure the number and specific weight of all the urine taken during the day. If daily diuresis is 60-80% introduced into the body of liquid (the rest of the fluid is excreted in sweat, feces, exhaled air), and the share of urine reaches 1020-1025, the total renal function should be considered normal.
Functional completeness of the kidneys is largely determined by their ability of accommodation to different conditions. Water stress and xerophagy can detect dynamic adaptability of the kidneys and their reserve forces. This is the test for breeding and concentration, each sample is carried out within 12 hours.
Test for breeding is carried out as follows. The patient drinks on an empty stomach 1.5 liters of water or weak tea, then for 4 hours investigate the number and proportion of single servings of urine collected every half hour. Over the next 8 hours portion of the urine is collected every 2 hours. Healthy kidneys to excrete drunk 1.5 l in about 4 hours, half of that amount - within the first 2^hours. Specific gravity of urine at first drops to 1000, then it gradually increased in parallel with the reduction of one-time portions of the urine and approximately 1030. If not, then there is a total failure of the kidneys caused this or that disease.
When the sample concentration patient does not drink for 12 hours; from food ration excluded products containing liquid. Urine is examined for 12 hours every 2 hours. In norm the proportion rises to 1025-1030, one portion of urine does not exceed 30-50 ml If the specific gravity of the urine reaches 1020, it indicates a violation concentrate ability kidney. If at the end of the sample on the cultivation of specific gravity of the urine increases to 1030, the sample concentration becomes superfluous. Sample dilution and concentration lose their value with considerable loss of fluid - diarrhea, vomiting, sweating, and in the presence of edema, ascites, diabetes insipidus and diabetes.
Kidney function under normal conditions can be Defined less burdensome for the patient breakdown of zimnitsky tests. The normal diet, urine during the day are collected every 3 hours. In norm the share of urine varies with this sample within 1010-1025 and the daily amount of urine is approximately 75% of the amount of liquid drunk during the same period.
About the General functions of the kidneys can be judged by the content in the urine of the decay products of protein, urea, indican, uric acid, creatinine, and other Most often use the quantitative determination of protein-free nitrogen blood - residual nitrogen.
Normally, the amount of residual nitrogen in the blood varies from 20 to 45 mg%. The level of residual nitrogen above 45 mg% indicates a failure renal function. In severe cases, uremia blood levels of residual nitrogen could rise to 200 - 300 mg% and more.
On the status of renal function also gives an idea blood testing for the content of individual protein cleavage products such as urea (the normal concentration of 20-40 mg%), indican (in norm to 0.8-1 mg%) or creatinine (OK 0,6 - 2 mg%).
More correct idea of kidney function gives a comparison of the contents of these toxins in the blood and urine. If the delay in the blood depends on insufficient kidney function, the content in their urine should be reduced. Based on this principle fineness of purification, or clearance-test (clearance).
There are so-called threshold substances that are filtered by the kidney, but not absorbed and does not secretiruyutza tubules, such as inulin or paralingua acid. Being introduced by venepuncture into blood, these substances in the normal functions of the glomeruli must be contained in blood and urine in equal concentrations. If, for example, in 1 ml of plasma contains 1 mg of inulin, and in the urine, received in the bladder for a minute, contains 100 mg of inulin, then through the glomeruli in the time spent at least 100 ml of blood. This is determined by the speed of renal blood flow and filtration capacity of the glomeruli. Then, applying successively substances that not only are filtered by the kidney, but also absorbed or are secreted by the channel, you can re-examination of individual units of blood and urine tests every 30-60 minutes to calculate how reabsorbtion and secretory function of the tubules. The result is in the form of value, expressed in percentage established norms and specific to a particular substance. Each substance has its own size (coefficient of purification), denoting the number of blood or plasma, which in a minute OK fully released or cleared of a substance.
Almost most often determine the plasma purification from urea. Urea only close to the doorsteps substances, but this method does not require intravenous drip to foreign substances, and the number of repeat venepunktsii reduced from 8-10 to 3-4.
The cleansing formula for inulin:

where U is the concentration of inulin in urine (in milligrams-per cent);
V-the amount of urine that is allocated per minute;
R - concentration of inulin in the blood. For inulin, and thereby to clubockova filtering, is 125 ml per minute.
The cleansing formula for urea:
where Cm is the maximum purification; Cs - standard cleansing; U - concentration of urea in the urine; its concentration in the blood; V - the amount of urine. Cm normal ranges from 39 to 95, and Cs-from 31 to 52 ml of blood per minute. The average figure for Cm - 60, and for Cs - 44 ml of blood per minute. Kidney function of purification of blood urea is estimated in percentage in relation to the norm.
Method of purification shows that in acute glomerulonephritis suffers mainly clubockova filtering, chronic nephritis disturbed function as glomeruli and tubules; chronic pyelonephritis is broken kanalzevu secretion, but mainly upset and severely oppressed the tubular reabsorption.
For diseases or injuries of one kidney is necessary to study, in addition to the General and separate the function of each kidney. Used mainly colorful sample (chromatotherapy), excretory urography and urine examination separately obtained from each kidney.
If chromolithography after the introduction into the bladder cystoscope inject intravenously sterile 0.4% solution of Indigo Carmine (3-4 ml), who report the news, and watch the time of appearance of colored urine from the mouth of each ureter, paying attention to the colour intensity (see Fig. 34).
Under normal function of the kidneys and ureters after 3-4 minutes from the mouth of each ureter starts periodically get out a stream of colored blue urine (see Fig. 34). If the function of the kidneys, pelvis or ureter violated, the allocation of Indigo Carmine from the corresponding mouth will be late or it just will not stand out.
If it is impossible to enter the Indigo Carmine injected into a vein 15-20 ml of 0.4% of a solution intramuscularly. The allocation of colored urine occurs in 10-15 minutes.
Indigocarmina sample has some drawbacks. So, when the sample is impossible to distinguish a violation of secretory function of kidneys from disorders of the urinary functions of pelvis and ureter in addition, Indigo Carmine can be allocated on time and with the defeat of kidneys (such as a tumor), if there is even a small area of normal tissue. Therefore, rely on only one indigocarmina trial impossible. The result should be confirmed by other surveys.
Excretory urography is both a method of morphological and functional diagnostics. At normal function of the kidneys contrast, the substance fills the buckets after 5 minutes of intravenous administration. The time of appearance of contrast solution in the pelvis and ureter and the intensity of their filling allow to judge about the function of the kidneys, pelvis and ureter with each side separately.

Fig. 47. Isotopic renogram.
I - normal isotope runogramma; II - hydronephrosis left, right - normal runogramma left dramatically slow excretory segment; III - aplasia of the right kidney, left - normal runogramma, right - sharply reduced the segment And are missing segments In secretory and urinary S.

The results of the study of a specific gravity of urine collected from each kidney, and the content of urea, chlorides, uric acid are valuable indicators for the evaluation of separate functions of the kidneys. The same applies to the colorful samples with phenol-surfoffline, salicylic sodium, the sample with potassium permanganate or the test load florijana (glucoside). However, these methods are imperfect, as catheters long time are in the pelvis for collecting urine that is painful for the patient and at the same time, distort, to a certain extent a function of the kidneys. Therefore, in practice these methods currently used rarely.
Usually complex functional kidney samples used most often, consists of: 1) samples of zimnitsky tests, tests for breeding and concentration, 2) indigocarmina samples, 3) excretory urography, 4) blood tests for residual nitrogen urea or, on indican or creatinine. It should be guided not the result of any one sample, but a group of them.
Isotope renography - a new method of determination of partial functional ability of the kidneys, i.e. each of them separately.
The patient is injected 5-8 ICC radioactive iodine-geparina (sodium salt ortho-iodine-the hippuric acid), dilute 0.5 ml of physiological solution, iodine-Hepburn out from the body only by the kidneys. Radiation isotope consistently passes through the blood vessels, bone, and Cup-pelvis system of the kidneys, is captured by special devices - scintillators set on the skin of each kidney, and transmitted to the electronic recording mechanism that plays catch pulses in the form of the curve for each kidney separately (for example, right kidney - red for the left - green).
Each curve consists of three segments: A - vascular, characterizing renal blood flow, In - tubular, reflects the function of the renal tubules and - excretory describing the function of the urinary apparatus of kidneys.
The third scintillator set in the heart. He gives curve (blue color), describing the total renal function on the degree of purification (clearance) of blood from isotope.
Mapping all three curves gives isotope renogram, which depending on changes segments a, b and C - level and length of each segment, fast accumulation and excretion of the drug - can be judged not only on the total and separate functions of the kidneys, but also on the localization of the pathological process in a particular segment of the nephron (Fig. 47).