Clinical urinalysis is a widely used and common test that can be performed in he alth care settings, including the family physician's office, emergency rooms, medical laboratories, and even at home.
Complete urinalysis, abbreviated OAM, is an affordable and inexpensive, but quite informative method for diagnosing various pathological conditions and diseases. Some doctors even refer to OAM as a "cheap kidney biopsy" due to the amount of information that can be obtained about their he alth or other internal organs with this simple test.
Urine is assessed by its appearance (macroscopically): color, transparency/turbidity, smell - and microscopically (molecular properties, quantitative and qualitative ratio of chemical elements in it, examination of sediment).
Referral for analysis
OAM appointeddoctors for a number of reasons, including:
- During a routine medical check-up: annual check-up, pre-surgery check-up, first-time clinic visit, control of kidney disease, diabetes mellitus, hypertension (high blood pressure), liver disease, etc.
- To evaluate individual symptoms: abdominal pain, painful urination (dysuria), lower back pain, fever, blood in the urine (hematuria) and other urological symptoms.
- When diagnosing internal pathologies: bacterial cystitis and nephritis, kidney stones (nephrolithiasis), uncontrolled diabetes mellitus (type 2), kidney disease, myositis (muscle inflammation), protein in the urine (proteinuria), hatchability screening drugs and inflammation of the kidneys (glomerulonephritis).
- To monitor disease progression and treatment dynamics (response to therapy).
- When determining pregnancy.
The deciphered result of a urine test can reveal diseases that have gone unnoticed because they do not cause overt clinical signs (visible symptoms). These diseases include: diabetes mellitus, interstitial and hypertensive glomerulonephritis and chronic genitourinary infections.
The most economical urine screening device is a paper or plastic test strip. The dry microchemistry measuring system has been available for many years and allows clinical urinalysis to be performed within a couple of minutes. Now let's take a closer look at each of the existing methods.research and interpretation of urine tests in the table.
Methods of collecting urine
To perform the test, you must collect a urine sample from the patient in a special container. A small volume of liquid is usually required (about 30-60 ml). The study can be carried out both in a conventional medical center and in a laboratory. There are several methods of collecting material:
- Random collection at any time of the day without special preparation to prevent contamination (clogging) of the material. The collected urine is weakly concentrated, isotonic or hypertonic (depending on the amount of s alts dissolved in it) and may include white blood cells (leukocytes), bacteria and squamous epithelium as contaminants (impurities). In females, the specimen may contain vaginal discharge, menstrual blood, and trichomonas and yeasts.
- Urine solution collected early in the morning on an empty stomach. Usually this portion is hypertonic (highly concentrated) and reflects the function of the kidneys to slow down the formation of urine at night (dehydration after sleep). If you stop eating and drinking after 6 pm, then the next morning the density of urine can normally exceed 1.025.
- Clean, middle part of the urine is collected after flushing the external urethra. To do this, any cotton cloth moistened with 0.9% isotonic saline will do. The middle portion is the one in which the first jets of urine are passed, and into the containerthe last half of the urine stream is collected. The first jets are used to flush the urinary tract from contaminants.
- The introduction of a urological catheter into the cavity of the bladder through the lumen of the urethra is carried out only as a last resort, when the patient is in a coma or unconscious. Since with this procedure there is a high risk of infection, injury to the urethra and bladder wall, which leads to iatrogenic (due to the fault of the doctor) introduction of pathogenic microbes or bloody, painful urination.
- Transabdominal aspiration bladder puncture (cystocentesis). In this case, the needle is inserted into the cavity, piercing the abdominal wall, and the necessary portion is taken into the syringe. Subject to all the rules of asepsis / antiseptics, the resulting urine is practically sterile from microorganisms. Cystocentesis is highly used in deciphering urinalysis in children.
Macroscopic indicators of urine
There are several of them. During the decoding of the result of a urine test (the norm is in the table at the end of the article), its visual component is first evaluated, that is, what is visible to the naked eye. Normal, fresh urine has all possible shades of yellow and amber with pronounced transparency. The physiological volume of daily urine varies from 700 ml to 2 liters.
Opalescence (turbidity) appears with excessive cellular material or with an abundant content of proteins in the urine. Turbidity of urine is also visible in case of violation of the terms and methods of storage of the material in different temperature conditions, the longer the urine is stored, the morecrystallizes and precipitates s alts.
Redness with a brownish tinge indicates an admixture of food or medicinal dyes, the presence of hemoglobin or myoglobin. Blood in the urine is also one of the main causes of not only redness, but also cloudiness.
Therapist can simply perform a rapid strip test at the appointment. It will only take a few minutes. And at the same time, the doctor can send one middle part of the urine to the laboratory for culture (urine culture). It will take several working days to decipher the result of the urine analysis of this test. The results of the culture will show the attending physician which specific bacteria caused the infection, and to which antibiotics this type of organism is sensitive and resistant.
This test should also be accompanied by other types of research. Additional checks and clinical evaluation are often needed to objectively interpret the urinalysis in adult and elderly patients and ultimately reach a diagnosis. For example, UTI (urinary tract infection) is usually diagnosed on the table of norms for deciphering urine analysis in adults. However, culture is more often used as a control test to identify specific microbes and confirm the diagnosis.
Who studies information
Deciphering the results of a urine test, as a rule, is based on the study of all components of the test and its comparison with clinical signs andphysical examination. The attending physician who ordered the examination is engaged in decoding. But nevertheless, independent study of the results is also acceptable.
Common urine test with test strip
The rapid test is a paper strip with indicator marks impregnated with chemicals that change color in the presence of certain urine components at a certain concentration. The intensity of staining depends on the concentration of these substances. The strip is immersed in the urine sample and, after a few seconds, is removed and compared with the color chart on the package to decipher the urine test.
pH
Filtered through the glomeruli, blood plasma acquires an acidic environment ranging from 7.6 to 5.8 in the final urine. If the acid-base state of the blood is different, then the pH of the urine can vary from 4.4 to 8.1. Deviations of this parameter from 7.5 occur in the descending collecting ducts and the collecting duct of the kidneys.
Specific Gravity
The specific gravity (or density) of urine is determined by the presence of substances dissolved in it, represented by particles of various sizes, from small ions to larger proteins. Urine osmolarity measures the total amount of dissolved substances, regardless of their size. The most common method is to lower the freezing point of urine. A refractometer measures the change in light path direction (refraction) based on the concentration and size of particles in a liquid. Large elements such as glucose andalbumin, will change the refraction to a greater extent. Measurement of specific gravity with a rapid test strip is approximate, so you should not fully trust this indicator as a result of the analysis.
Normal specific gravity is considered in the reference value from 1.004 to 1.036, in the absence of kidney pathologies. Since the specific gravity of primary urine in Bowman's capsule ranges from 1.004 to 1.008, a decrease in it indicates a high level of fluid, and an increase indicates dehydration.
If, in the absence of food for 8-10 hours and water for 2 hours before the test, the density of urine is below 1.020, this means that the filtration capacity of the kidneys is reduced, which happens with generalized renal failure or renal diabetes mellitus. In the later stages of the disease, the density of urine becomes from 1.005 to 1.008.
If, when deciphering the analysis of urine in adults according to the table, its specific gravity is more than 1.037, or the shelf life of urine is violated, it contains a large amount of glucose impurities. During excretory intravenous urography, when a contrast agent is injected into a vein, its density also changes.
Protein
Semi-quantitative screening of urine for protein content should be done using laboratory equipment, as the test strip often gives a falsely high protein value. Usual normal protein excretion does not exceed 150 mg per day or 10 mg/100 ml in one sample in adults. More than 150 mg per day is defined as proteinuria. Proteinuria> 3.5 g per day is veryserious condition - nephrotic syndrome.
Glucose
Urine normally contains less than 0.1% glucose (<130 mg/24 hours). Glucosuria (excess sugar in the urine) generally means diabetes mellitus. In this case, a test using a test strip is considered a reliable determination of glucosuria.
Ketone bodies (Ketones)
Ketone bodies (acetone, acetoacetic acid, beta-hydroxybutyric acid) appear in the urine as a result of diabetic ketosis or during prolonged fasting. Easily detected with a simple rapid test. Normally, there should be no ketone bodies in the urine.
Nitrogen (Nitrite)
A positive nitrite test indicates that a significant amount of nitrogen-forming bacteria is present in the urine. Gram-negative rods such as E. Coli (E. coli) are more likely to test positive.
Leukocytes (WBC - white blood cells)
A positive leukocyte reaction is due to the presence of white blood cells in the urine (pyuria, leukocyturia). This reaction also indicates an active inflammatory process or infection. A negative result translates into a low probability of infection.
Microscopic analysis of urine
A sediment is prepared from the obtained urine sample, then a study is carried out using a microscope under low and high magnification. This method can detect epithelial cells, crystals of kidney and urinary stones, bacteria, blood cells, etc.objects.
Erythrocytes (RBC - red blood cells)
Hematuria is the presence of an abnormal number of red blood cells in the urine due to glomerular damage, urinary tract tumors, kidney injury, urinary stones, kidney infections, acute tubular necrosis, UTIs, nephrotoxins and physical stress. Theoretically, not a single red blood cell should normally be found in the urine sediment, but sometimes they are found in small numbers in he althy people.
Epithelial cells
In chronic nephrosis, the total amount of renal and urinary epithelium is deposited at the bottom of the urine. A small amount of epithelium is physiologically acceptable.
Leukocyte casts in the urine sediment are most characteristic of acute inflammation of the renal pelvis, but are also detected in glomerulonephritis, since they form only in the kidneys.
In the terminal (last) stage of renal failure, any urinary inclusions are practically absent, since the remaining few living kidney cells cannot produce concentrated urine.
Crystals
Common crystals are visible in the urine sediment even in the absence of urolithiasis, they include: calcium oxalates, tripelphosphates and amorphous phosphates.
Atypical crystals include cystine formations in the urine of newborns, which indicate congenital liver failure, and tyrosine crystals in a child, severe liver disease.
Interpretation of results
Below is the decryption tableurinalysis is normal.
This is how the test indicators are deciphered when they are normal.
