Statistical procedures were employed using the software Graph Pad Prism, version 5. Initially, the physical analyzes color, appearance and density of 80 urine samples were carried out.
Figure 1 shows that the urine samples that were at room temperature and the refrigerated ones showed virtually no difference in terms of color. Nevertheless, after 24 hours at room temperature, four samples changed their hue from yellow to dark yellow 3 and red 1. Regarding aspect Figure 2 , 38 out of 80 urine samples, which had been kept at room temperature, were clear at the time of collection and 31 remained with the same aspect throughout the period of analysis.
The remaining 7 samples became cloudy in analyzes performed after 24 hours. A completely different result was observed in the samples stored under refrigeration. In this method of storage, it was observed that after a six- hour refrigeration period some samples became cloudy or slightly cloudy despite the fact that most of them remained clear.
In analyzes performed 12 and 24 hours after collection, there was an inversion of the profile with the predominance of cloudy and slightly cloudy features. Therefore, at time zero, 38 samples were limpid and only 11 samples presented this characteristic by the end of the hour refrigeration period.
As to the density analysis, it was observed that all samples, refrigerated or not, yielded results within 1. Regarding the samples that were kept under refrigeration, only 3 showed an increase in density by 0. In the chemical assessment, it was observed that 45 out of 80 selected urine samples showed no chemical change detected by the reagent strip when analyzed at room temperature at the time of collection. Even after refrigeration, these 45 samples did not present any chemical change, corroborating the data presented during this study.
Thus, refrigeration did not exert any effect on chemical analysis, which could lead to positivity. In the remaining 35 samples, one or more abnormal elements were detected on the reactive strips immediately after collection Table 1. In these samples with chemical changes, which had been kept under refrigeration and analyzed after 6, 12 and hour periods, there was no qualitative or semi-quantitative change in the screening in contrast with the analysis upon arrival at the laboratory.
Regarding the samples stored at room temperature, Table 2 shows changes in some chemical parameters in contrast with the results obtained from those immediately analyzed. In the analysis after 24 hours, the three samples began to show a positive nitrite reaction, two were negative for leukocytes and one was negative for glucose.
As to the pH of the 80 samples kept under refrigeration and assessed by the reactive strips, there was pH change from 6. Conversely, in samples kept at room temperature Table 3 , there was change in 9 of them, mainly 24 hours after collection.
After the physical and chemical analyzes, ACS screening of formed elements in the refrigerated urine samples revealed no differences in the results of epithelial cells, pyocytes count, erythrocyte and bacteria in relation to samples assessed at the time of collection.
However, a rise in urinary sediment crystals proportional to the cooling period was observed during the qualitative and semi-quantitative analysis, especially calcium oxalate, urate and amorphous phosphate crystals Table 4. Initially, only 7 out of 80 samples presented crystals. By the end of the hour cooling period, 36 urine samples showed precipitated crystals and several with more than one type of crystal. When kept at room temperature for 24 hours, the number of samples with crystals at the time of collection changed from 7 to 10 with precipitation of crystals.
Regarding the urine stored at room temperature, the analysis of pyuria by microscopy revealed that the number of cells decreased during the hour period.
This was corroborated by the urine strip results that showed 9 positive samples. This reduction was not observed in urine samples kept under refrigeration even after 24 hours. In the samples stored at room temperature, 10 samples showed significant bacteriuria after 12 hours, accruing to 14 samples after 24 hours, whereas the 8 urine samples that initially presented bacteria did not undergo any changes.
Urinalysis is one of the most requested tests in clinical medicine. The preanalytical phase is of paramount importance in all laboratory tests, including urine examinations. In ACS analysis, some guidelines should be followed as to cleaning of external genitalia, suitable collection of material and immediate referral to the laboratory 2, 14, The urine sample submitted to the laboratory must be analyzed within two hours after collection at most.
Refrigeration is the most applied preservation method in clinical laboratories and it is able to prevent bacterial decomposition. Nevertheless, the literature describes that cooling may result in increased density assessed by urine densitometer 16, This data was corroborated by the experiment, which also varied in relation to the density of cooled samples, insofar as six of them indicated increase in this parameter.
Conversely, the samples kept at room temperature underwent changes in the chemical tests, namely an increase in the presence of nitrite and a decrease in the samples with leukocytes and glucose Table 2. The rise in nitrite correlates with the bacterial metabolism in the urine sediment, which is equally observed in the material maintained at room temperature during sedimentoscopy. The study by Santos et al. As noted by Silva et al. The bacteria in the urine sample can multiply if it is not kept in a fridge.
If this happens, it could affect the test results. Your GP or another healthcare professional may ask for a urine sample to help them diagnose or rule out certain health conditions.
Urine contains waste products that are filtered out of the body. If the sample contains anything unusual, it may indicate an underlying health problem. Find out more about operations, tests and procedures. Page last reviewed: 27 August Next review due: 27 August Home Common health questions Infections Back to Infections.
In some instances, results are so severely affected that an accurate diagnosis cannot be made. Preferred sample collection methods depend on the suspected disease process, patient species and temperament, technical skills of the collector, and available technology or resources See Table 1.
Regardless of method used, always collect as much urine as possible, preferably at least 5 mL. Sample collection methods can sometimes affect urinalysis results. For instance, urine collected from voided samples has the highest risk of bacterial contamination.
Often, voided urine samples are collected from floors, exam tables, reused collection containers ladles, pie tins, cups, etc. Also, voided urine samples may pick up bacteria from the skin or fur of veterinary patients increasing the risk of contamination.
In cases of suspected urinary bladder infections or high urine protein concentrations in small animals, samples collected via cystocentesis are best. Bacteria present in cystocentesis samples represent bacteria in the urinary bladder i. When a cystocentesis cannot be performed, sterile urinary catheterization is recommended. Manual bladder expression is not recommended as a routine urine collection method due to vesicoureteral reflux Figure 1.
When a full urinary bladder is squeezed, urine will flow up the ureters toward the kidneys before exiting the body via the urethra. If a urinary bladder infection is present, bacteria is pushed up into the kidneys and could result in a severe kidney infection i. Sign in.
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