No plastic tubes please. Phone: Fax: Email: diagcenter cornell. Business Hours Monday-Friday: ampm Saturdays limited service : ampm. Print This Page. Normal Results The normal range for hour urine volume is to 2, milliliters per day with a normal fluid intake of about 2 liters per day. Results are dependent on the proper collection of your urine sample. Normal urine creatinine values generally range from to 2, milligrams mg per 24 hours for males, and to 1, mg per 24 hours for females, according to the Mayo Clinic.
For reducing the risk of errors and contamination, commercially available vacuum systems have been developed, allowing direct sample aspiration into a secondary container. Vacuum systems can only be used for chemical analysis and are not recommended for particle analysis. During vacuum aspiration, the pressure difference results in a desintegration of brittle casts. The reduction of cast counts depends on the vacuum during aspiration A destruction of cellular casts which are only weakly hold together by the sticky Tamm-Horsfall protein is observed due to mechanical damage during vacuum aspiration, with a release of their cellular inclusions, as demonstrated by an increased amount of erythrocytes and leukocytes.
At this moment, only particle analysis will result in true identification of casts. The available assays measuring Tamm-Horsfall protein can provide information on the presence of casts, without verifying the nature of the casts. The influence of vacuum systems on other elements is limited. No difference in flowcytometric erythrocyte count and the percentage of nonlysed erythrocytes has been observed for urine samples with normal osmolality conductivity in conventional and vacuum test tubes.
Peroxidase-based haemoglobin dipstick reactions were comparable. Because of the growing importance of micro albuminuria in the diagnosis of kidney disease, more attention has been paid to the particular preanalytical aspects of this analyte.
At low albumin concentrations, adsorption to the surface of urine containers can lead to marked relative losses Binding to surfaces may also result in protein denaturation. Addition of nonionic detergents or using hydrophilic surfaces may reduce both adsorption and denaturation. Albumin is relatively stable at the air-liquid interface when rapid mixing generates foaming. An increased time lag between sampling and analysis, a lack of temperature control and a lack of addition of a preservative to samples for which urinalysis cannot be performed within two hours of collection, will lower the quality of urinary test results.
The exact sampling time and delays exceeding the specified limits should be documented. Point-of-care analyses are not subject to this delay, but may as well be affected by various analytical issues. Influence of temperature on stability of particle analysis adapted from reference Influence of temperature on test strip analysis adapted from reference Alkaline pH, low relative density and low osmolality can induce a rapid lysis of some urine particles after collection Addition of stabilizers usually prevents metabolic changes of urine analytes and overgrowth of bacteria.
However, preservatives may affect some chemical properties and alter the appearance of particles. An appropriate label carrying a hazard symbol should give information dealing with any preservative 10 , 13 , Risk of sample dilution and its potential influence on outcome of urine culture are important issues when using liquid mixtures. The correct preservative to specimen ratio should be respected when samples are preserved for transport and analysis 8. The recommended specimen volume is mostly indicated on the container with a marking line.
If too much sample is added to the container, the concentration of the preservative gets too low, reducing the preservative action. In the inverse situation, an excessive amount of preservative may inhibit bacterial growth.
The minimal urine volume needed in order to obtain correct results has been determined for two different preservative-containing systems Lyophilised formulations should be chosen among the commercial preservatives as there is no risk of sample dilution of spillage. Also, containers supplemented with boric acid alone or in combination with formic acid or other stabilizing media, are used 10 , Table 2A depicts the effect of commonly used preservatives on flow cytometric particle analysis. In contrast to casts, epithelial cells and leukocytes, the stabilization of erythrocytes is extremely difficult, probably due to cellular shrinkage following the addition of formaldehyde solutions Very good.
Not good. In function of the required testing, a difference in preservative demands is requested. In particular, laboratories should focus on the analytical test quality, as more reliable results ask for stricter pre-analytical demands.
Several specific proteins are instable in urine, which could be resolved by inhibition of their degradation by the addition of some preservatives. Although the hour urine collection is the reference method for quantification of stable chemical analytes, contamination, incorrect collection and incorrect calculation of urinary volume can cause preanalytic errors. The albumin: creatinine ratio or protein:creatinine ratio on a random urine sample, which is not influenced by variation in water intake and rate of diuresis, is a recommended alternative For monitoring proteinuria, the reliability of protein:creatinine ratio still needs to be proven 9 , When analysis of the test strip can be performed within 24 hours and the urine specimen has been refrigerated, no preservatives are needed Freezing cannot be regarded as an alternative for refrigeration in preserving samples for urine test strip analysis.
The selection of the preservative partly depends on the required analyses since some enzymatic reactions may be influenced by preservatives Table 2B 10 , 26 , The use of boric acid affects a number of test strip reactions.
This limits the proposed combination of test strip analysis and urine culture to obtain an optimal diagnostic test use. Boric acid keeps urinary pH below 7, prevents dissolution of pus cells 29 and is associated with false negative strip test results e. Although it cannot be considered as good laboratory practice, in some laboratories dip slides are put in a urine containing test tube while using the same sample for other types of analyses.
Several reports highlight contamination of the sample by glycine 2 , iodine 30 , caffeine 31 and other constituents of the test strip, which leads to unnecessary further investigation. To resolve this problem, urine should be transferred to the strip instead of immersing the test strip into the specimen. Dipping is only acceptable if a separate aliquot is available. A detailed table for the correct preservation of hour urine specimens published by the National Committee for Clinical Laboratory Standards NCCLS and CLIS is based on the recommendations of the major textbooks and the largest reference clinical laboratories e.
Mayo Medical Laboratories. As specimen requirements can be conflicting when a number of tests are required, several different approaches have been proposed ranging from collection of multiple hour specimens to the use of containers with a two-way split or three-way split of the preservative. When a hour urine volume exceeds the volume of a single container, the urine of two hour containers should be well mixed before analysis.
It is recommended to regularly check the current requirement from reference laboratories as they may change from time to time 10 , 13 , 32 , Due to the presence of alkaline medication or stale urine, highly buffered alkaline urine pH 9 may result in false-positive test strip results for proteinuria. A similar phenomenon is observed a if the test strip is left submerged in the urine sample for a too long time period, b if quaternary ammonium compounds are used for cleaning the urine containers, c if patients are treated with polyvinylpyrrolodione or phenazopyridine, d if skin cleansers with chlorhexidine gluconate are used or e if blood, vaginal discharge, pus, semen or heavy mucus are contaminating the specimen.
False-negative results are reported in diluted urine or in the presence of slightly elevated proteinuria other than albuminuria globulin, immunoglobulin, light chains 10 , At this moment, no urinary components have been associated with false-positive glucose oxidase reactions.
However, contamination with strong oxidizing cleaning agents peroxide or hydrochloric acid can result in a false-positive reaction. Using automated methods for some brands of reagent strips, falsely elevated urinary glucose test strip results can also be caused by elevated urobilinogen concentrations In addition, the temperature can affect the sensitivity of glucose due to its effect on the enzyme reaction.
For that reason the test should be repeated at least one day after the last intake of vitamin C. False-positive reactions for ketones or ketone bodies are seen in a urine samples with a low pH and a high specific gravity, in b urine containing a high amount of levodopa metabolites, c in the presence of compounds with sulfhydryl groups e.
An improper storage can lead to false-negative results and beta-hydroxybutyrate is not detected 10 , Screening tests for occult blood can become false-positive by a certain oxidizing contaminants hypochlorites when cleaning urine containers or in the presence of bacterial peroxidases by a high bacterial content 37 , 38 or by b contamination with povidone-iodine 39 , c menstrual blood, d semen or e myoglobinuria 34 , As urine dip-sticks are characterized by a very high sensitivity for intact erythrocytes and free hemoglobin, transient hematuria is a common finding.
To rule out transient hematuria, the urinalysis should be repeated on different occasions in asymptomatic patients with a positive dipstick result for hematuria and an otherwise normal urinalysis. If persistently positive results for blood are found, clinicians should confirm the presence of erythrocytes in urine by a microscopic sediment analysis.
A strongly positive dipstick in combination with a non-corresponding negative urine sediment can be explained by lysis of erythrocytes and release of free hemoglobin in patients with dilute urine of normal colour.
The same finding in subjects with grossly bloody urine specimens is suggestive of intravascular hemolysis or rhabdomyolysis A comment released together with observed unchanged dipstick test results pointing to the probable interference could be informative. In contrast, false-negative results can be found when the examination is delayed, when urine specimens are not well mixed before testing or when using formalin as preservative.
A lower sensitivity is sometimes seen after the intake of a high amount of ascorbic acid, after the intake of captopril, in urine samples with a high concentration of proteins or nitrites or with a high specific gravity 10 , The interpretation of the bilirubin pad is unreliable after the expire date.
False-positive reactions can be induced by indican and metabolites of etodolac, by the intake of phenazopyridine or large doses of chlorpromazine or phenazopyridine. A lower sensitivity is observed after the intake of large amounts of ascorbic acid, in the presence of a high nitrite concentration or after the exposure to light 10 , Atypical reactions with the urobilinogen pad have been reported by several interferering components: p-aminobenzocic acid, sulphonamides, paminosalicyclic acid, phenazopyridine and p-dimethylaminobenzaldehyde.
In addition, coloured urine and prophobilinogen can result in false-positive reactions. False-positive results for nitrite are seen after a too long standing at room temperature for several hours or when urine appears red.
The leukocyte esterase test can give false-positive reactions due to the use of strong oxidizing agents, formaldehyde 0. In addition, coloured urine bilirubinuria and beet ingestion can result in a positive reaction. The limitations of the detection of bacteria by multiple test strips are the following: coloured urine and in vitro growth can result in false-positive reactions, whereas a short bladder incubation time, Gram-positive bacteria, vitamin C or no intake of vegetables can give false-negative results Alkaline urine, glucose and urea can decrease the sensitivity of the analysis Refrigeration causes a precipitation of phosphates and urates, which may affect analysis of these analytes.
Hence, preparing a separate non-refrigerated aliquot is necessary if differentiation of urinary crystals is requested. Assessment of leukocytes gets doubtful when the analysis is performed more than 4 hours after sampling.
However, without adding a preservative, leukocyte preservation can be fairly good even when samples were stored at room temperature for 72 h.
These positive results in preserving leukocytes should be interpreted with caution, as only samples of adults had been selected In pediatric specimens kept at room temperature, a rapid decrease in the white blood cell count was observed Particle lysis accelerates with increasing pH too long time lag between collection and analysis, Proteus sp.
Falsely elevated red blood cell counts measured by flow cytometry could be the result of undissolved powder in the urine container test tube causing a background noise signal Morphological erythrocyte analysis remains a separate component of urine particle analysis.
Urinary tract and renal diseases can be associated with haematuria. However, also a general bleeding disorder or physiological reasons e. The morphology of urinary erythrocytes may reflect the origin of bleeding: dysmorphic erythrocytes red cells characterized by an abnormal shape or size , especially acanthocytes or G1 cells a ring-shaped body with one or more protruding blebs , point toward renal disease.
Red blood cells with a normal morphology usually originate from the lower urinary tract A more general use of this time-consuming test is hampered by the lack of unequivocal criteria for identification and quantitation of dysmorphic erythrocytes and the special training phase contrast microscopy needed for this examination Morning urine specimens should be preferred as correct evaluation of erythrocyte morphology depends on osmolality and pH An alternative approach to differentiate the bleeding site is based on specific protein analysis, e.
Several methods have been developed for the detection of urinary elements. In the classical manual particle analysis, the presence of formed elements like red and white blood cells, epithelial cells squamous and non-squamous epithelial cells , urinary casts hyaline and cellular , spermatozoa, bacteria, yeasts, various artefacts e.
Hence, a sediment method can never be considered as reference of quantitative urinary particle counting Although centrifugation with removal of supernatant is necessary for sample concentration, it remains a major source of errors.
Large amounts of ketones in the urine may mean a very serious condition, diabetic ketoacidosis , is present. A diet low in sugars and starches carbohydrates , starvation, or severe vomiting may also cause ketones to be in the urine. Microscopic analysis. In this test, urine is spun in a special machine centrifuge so the solid materials sediment settle at the bottom. The sediment is spread on a slide and looked at under a microscope.
Things that may be seen on the slide include: Red or white blood cells. Blood cells aren't found in urine normally. Inflammation, disease, or injury to the kidneys, ureters, bladder, or urethra can cause blood in urine. Strenuous exercise, such as running a marathon, can also cause blood in the urine. White blood cells may be a sign of infection or kidney disease. Some types of kidney disease can cause plugs of material called casts to form in tiny tubes in the kidneys.
The casts then get flushed out in the urine. Casts can be made of red or white blood cells, waxy or fatty substances, or protein. The type of cast in the urine can help show what type of kidney disease may be present. Healthy people often have only a few crystals in their urine. A large number of crystals, or certain types of crystals, may mean kidney stones are present or there is a problem with how the body is using food metabolism. Bacteria, yeast cells, or parasites.
There are no bacteria, yeast cells, or parasites in urine normally. If these are present, it can mean you have an infection. Squamous cells. Symptoms of a urine infection may include coloured or bad-smelling urine, pain when urinating, finding it hard to urinate, flank pain, blood in the urine hematuria , or fever. To check the treatment of conditions such as diabetes, kidney stones, a urinary tract infection UTI , high blood pressure hypertension , or some kidney or liver diseases.
As part of a regular physical examination. How To Prepare Do not eat foods that can colour the urine, such as blackberries, beets, and rhubarb, before the test. How It Is Done A routine urine test can be done in your doctor's office, clinic, or lab. Clean-catch midstream one-time urine collection Wash your hands to make sure they are clean before collecting the urine.
If the collection cup has a lid, remove it carefully and set it down with the inner surface up. Do not touch the inside of the cup with your fingers. Clean the area around your genitals. A man should retract the foreskin, if present, and clean the head of his penis with medicated towelettes or swabs. A woman should spread open the genital folds of skin with one hand.
Then she can use her other hand to clean the area around the urethra with medicated towelettes or swabs. She should wipe the area from front to back so bacteria from the anus is not wiped across the urethra.
Begin urinating into the toilet or urinal. A woman should hold apart the genital folds of skin while she urinates. After the urine has flowed for several seconds, place the collection cup into the urine stream and collect about 60 mL 2 fl oz of this "midstream" urine without stopping your flow of urine.
Do not touch the rim of the cup to your genital area. Do not get toilet paper, pubic hair, stool feces , menstrual blood, or anything else in the urine sample. Finish urinating into the toilet or urinal. Carefully replace and tighten the lid on the cup, and then return it to the lab. Double-voided urine sample collection This method collects the urine your body is making right now.
Urinate into the toilet or urinal. Do not collect any of this urine. Drink a large glass of water, and wait about 30 to 40 minutes. Then get a urine sample. Follow the instructions above for collecting a clean-catch urine sample.
The collection period usually starts in the morning. When you first get up, urinate—but don't save this urine. Write down the time that you urinated to mark the beginning of your hour collection period. For the next 24 hours, collect all your urine. Your doctor will usually provide you with a large container that holds about 4 L 1 gal and has a small amount of preservative in it. Urinate into a smaller, clean container, and then pour the urine into the large container.
Avoid touching the inside of the container with your fingers. Keep the large container in the refrigerator during the collection period.
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