A Specific Gravity Reading of 1.000 Is Obtained by Reagent Strip Method on a Urine With a Ph of 8.0

Urinalysis

Urinalysis begins with a macroscopic examination of the urine which describes the color and clarity of the urine. In salubrious individuals urine color ranges from stake yellow to amber, depending on their state of hydration. Many factors affect urine colour including fluid balance, diet, medications and disease.  The following tabular array includes a list of the well-nigh common causes of abnormal urine coloration.

Color	Pathologic Causes	Nutrient & Drug Causes
Cloudy	Phosphorus, pyuria, chyluria, lipiduria, hyperoxaluria	Nutrition high in purine-rich foods causing uricosuria
Brown	Bile pigments, myoglobin	Fava beans, Levodopa, metronidazole (Flagyl), nitrofurantoin, anti-malarial drugs
Brownish-Blackness	Bile pigments, melanin, methemoglobin	Cascara, levodopa, methyldopa, Senna
Green or Bluish	Pseudomonas UTI, biliverdin	Amitriptyline, indigo, carmine, Four cimetidine (Tagamet), IV promethazine (Phenergan), methylene bluish, triamterene (Dyrenium)
Orange	Bile pigments	Phenothiazines, phenazopyridine (Pyridium)
Crimson	Hematuria, hemoglobinuria, myoglobinuria, porphyria	Beets, blackberries, rhubarb, Phenolphthalein, rifampin
Yellow	Concentrated urine	Carrots, Cascara

Dipstick Testing

Urine samples are initially screened with dipsticks. Performing microscopic analysis on merely dipstick positive urine samples is toll effective when the patient population being tested has a low incidence of potential disease. Numerous studies have determined that 6 to 20% of patients with urine sediment abnormalities are missed by this testing strategy. However, most of the missed cases are clinically insignificant and are often due to contaminating leaner multiplying after urine drove. Urine dipsticks are plastic strips with attached reagent pads for pH, poly peptide, glucose, ketone, bilirubin, urobilinogen, blood, nitrite, and leukocyte esterase.  The principle and performance of each dipstick examination is summarized below.

pH

The exam is based on a double indicator method (methyl red and bromthymol bluish) that covers the unabridged range of urine pH.  Colors range from orange through yellow and green to blue.  pH should be measured in fresh urine and read quickly.

The pH of urine is an indication of the kidney's ability to maintain a normal plasma pH.  Metabolism produces acids that are excreted by the lungs and kidneys.  The average adult urine pH varies betwixt 5 and 8.  A diet high in protein produces a more acid urine, while a vegetarian nutrition often produces a pH greater than half-dozen.  Heavy bacterial growth may cause an alkaline shift in urine pH by converting urea to ammonia.   Pigmented urine tin can interfere with pH readings. Bacterial contaminants, blood in the urine and contamination by genital secretions tin alter urine pH.

Protein

The protein test is based on a alter in color of a pH indicator (e.m. tetrabromophenol blue) in the presence of varying concentrations of protein when the pH is held abiding.  The reagent pad contains the indicator and a buffer that holds the pH of the pad at approximately three. Xanthous indicates undetectable protein.  The color of positive reactions ranges from yellowish-green to green to dark-green-blue. The accuracy of this examination depends on having urine that is slightly acidic. Dipsticks can detect poly peptide concentrations equally depression every bit five to xxx mg/dL. Urine protein concentrations are reported as 30, 100, 300, or 2000 mg/dL.

This test is optimized to detect albumin and is less sensitive in detecting globulins.  Dipsticks practice not notice beta-2- microglobulin or immunoglobulin light chains. Standard urine dipsticks are much less sensitive at detecting urine albumin than other assays. Dipsticks do not detect microalbuminuria.

Method	Typical Detection Limit(mg/dL)	Sensitivity (Relative to Urine Dipstick)
Dipstick Protein	18	ane
Spectrophotometric Urine Protein	6	3X more sensitive
Immunoassay for Urine Albumin	0.three	60X more than sensitive

Dipstick testing is useful simply when urinary protein exceeds 300 to 500 mg/twenty-four hours or albumin exceeds 10 to 20 mg/twenty-four hours.

The major crusade of a false positive urine protein is a highly alkaline sample.  Fake positive reactions tin can as well exist acquired by contamination with quaternary ammonium compounds (zepharin, chlorhexidine) used to clean the pare for a clean catch urine. Excessive contact with urine may wash out the buffering system and pb to a false positive result.  Confirmatory tests only need to exist performed on those urine samples with positive protein and a pH of 7.5 or greater.

Proteinuria can have many causes.  Postural proteinuria occurs in 3 to 5% of healthy adults and is characterized by the presence of protein in the urine during the mean solar day only not the night.  Strenuous exercise, fever, and exposure to farthermost heat or cold, pregnancy, eclampsia, stupor, and CHF cause functional proteinuria.  Hematologic malignancies, such equally multiple myeloma, may produce backlog immunoglobulin that is excreted in the urine.  Renal diseases are a common source of proteinuria.

Approximately 25% of urine specimens containing bacteria volition accept a positive protein reaction as the only positive dipstick reaction.  The esterase reagent is sensitive to 15 leukocytes per hpf, but the poly peptide reagent is sensitive to vi leukocytes per hpf.

Glucose

The dipstick test is based on a double enzyme method employing glucose oxidase and peroxidase. Color change ranges from green to brown. Minor amounts of glucose (<15 mg/dL) are normally excreted past the kidney, which is below the 75 mg/dL lower limit of detection of dipsticks, Glucose oxidase is specific for glucose and does not react with lactose, galactose, fructose, or reducing metabolites of drugs.  Glucose is reported equally 100, 250, 500, 1000, or >one thousand mg/dL.

Urine specific gravity and temperature may affect test reactivity.  High urine specific gravity tin reduce color development. Urine should be at room temperature before the test is performed to obtain optimum sensitivity.  False positive reactions rarely occur, but may be produced by strong oxidizing cleaning agents. Beta lactam antibiotics such as the penicillins, cephalosporins, carbapenems, and monobactams tin can cause false positive reactions.  Massive amounts of ascorbic acid (vitamin C), salicylates or levodopa can subtract the sensitivity of the exam.

Negative urine samples from pediatric patients under the age of 1 should be confirmed with a copper reduction method, such as Clinitest, to notice galactose or lactose.  Confirmation only needs to be performed one time on a patient.

Glucosuria usually occurs when the claret glucose level exceeds 180 mg/dL. Glucosuria well-nigh commonly occurs in patients with diabetes, infections, myocardial infarction, liver disease, and obesity.  Thiazides, corticosteroids, and nascence control pills may precipitate glucosuria.

Ketones

Dipsticks use the nitroprusside reaction to examination for acetoacetic acid.  They are less sensitive to acetone and do not notice beta-hyroxybutyrate.  The typical diabetic patient with ketoacidosis usually excretes 78% beta-hyroxybutyrate, twenty% acetoacetate, and 2% acetone. The reaction of acetoacetic acid with nitroprusside results in the development of color ranging from buff pink to shades of purple.  Color reactions are categorized every bit trace, small, moderate and large that stand for to ketone concentrations of v, fifteen, 40 to 80 and fourscore to 160 mg/dL of urine, respectively.   Dipsticks reliably discover ketone concentrations of 40 mg/dL or more than, so moderate and large readings do not demand to exist confirmed.  Trace and small readings should be confirmed by using Acetest.  The detection level for Acetest tablets is 20 mg/dL. The presence of ketonuria does not bespeak the need to practise further microscopic evaluation.

Normally, urine contains <2 mg/dL of acetoacetic acid, which is not detectable. A salubrious private may have detectable ketones if he/she has been fasting, strenuously exercising, or is pregnant.  Ketones are likewise detected in children consuming high fat diets.  Ketonuria is unremarkably seen in hospitalized patients due to fasting. Ketones are clinically significant only in the presence of urine glucose. Drugs with free sulfhydryl groups such as penicillamine, North-acetylcysteine, BAL and ACE inhibitors (captopril and enalapril) cause false positive reactions.

Ketones are volatile and evaporate from the specimen with time.  False negative results can occur with onetime urine samples.  The reagent pads are extremely sensitive to moisture and may become non-reactive afterwards exposure to humid room air for a few hours.

Blood

The dipstick exam for blood is based on the peroxidase-like activity of hemoglobin. Red cells are lysed on contact with the strip, allowing free hemoglobin to catalyze the liberation of oxygen from organic peroxide. Tetramethylbenzidine is oxidized, producing a colour change from orange to light-green-blue.  If intact ruby cells do not lyse, they may produce speckles on the pad. The sensitivity of dipsticks for hemoglobin is 0.015 to 0.062 mg/dL. This concentration corresponds to 5 to 21 RBCs/uL or 1 to 4 RBCs/hpf of concentrated urine sediment.

The reference range for RBCs in normal urine is 0-3 RBC/hpf in males and 0-12 RBCs/hpf in females when concentrated urine sediment is examined. This range corresponds to a concentration of 3 to 20 RBCs/uL of urine.  Dipstick sensitivity extends into the reference range.  Therefore, trace to ane+ reading may exist obtained on urine from every bit many every bit three% of healthy individuals.

In salubrious individuals, fewer than 1000 red cells are excreted in the urine per minute.  When 3000 to 4000 red cells are excreted per minute, 2 to 3 red cells volition be seen per high ability field, indicating microscopic hematuria. Gross hematuria occurs when more than i million red cells are excreted per infinitesimal.  Hematuria can be due to lesions within the GU tract involving the kidneys, ureters, bladder, prostate, or urethra.  The nearly common disorders include cancer, kidney stones, renal disease, urinary tract infection, and beneficial prostatic hyperplasia.  Transient hematuria can result from menstruation, viral illnesses, strenuous exercise, and mild trauma.  Anticoagulant therapy and chemotherapy may as well cause hematuria.  No etiology can exist determined in approximately 45% of cases of microscopic hematuria.

A positive dipstick examination for claret does non tell whether the reaction is due to ruddy cells, red cell casts, hemoglobin casts, or myoglobin. Many weather can lead to discrepant dipstick and microscopic findings. Any state of affairs that causes red cell hemolysis will requite a positive dipstick and negative microscopic result. Urine should be tested shortly later collection because scarlet cell lysis may occur as the sample ages, if the pH is alkaline, or if the specific gravity is ane.010 or less. Bacterially contaminated urine specimens may comprise sufficient peroxidase activity to produce a false positive reaction.  False positive reactions can too be caused by vegetable peroxidase.

False Positive Dipstick	False Negative Dipstick
Myoglobin	Dipsticks exposed to air
Oxidizing agents - bleach, detergent, iodine	RBCs settle out & urine not mixed
Bacterial peroxidase	Ascorbic acid (loftier concentration)
Vegetable peroxidase	Formaldelhyde (preservative tablets)
Betadine	High specific gravity
	Very high protein
	Urine pH <5.ane
	High nitrite from UTI
	Captopril (Capoten)

Bilirubin

The bilirubin dipstick test detects conjugated bilirubin and has a sensitivity of 0.five to 1.0 mg/dL.  This exam is based on the binding of conjugated bilirubin to diazotized salts fixed in the examination pad in a strong acidic surroundings to produce a colored chemical compound that is diverse shades of tan or magenta.  Positive dipstick tests are confirmed with the Ictotest. Normal adult urine contains about 0.02 mg/dL of bilirubin, which is not detectable by even the nearly sensitive methods. Confirmation of positive dipstick bilirubin results is most valuable when the urine specimen is stake yellow.

Ictotest is a tablet test that uses a similar chemic reaction just a different test surround. Urine is placed on an absorbent test mat that captures substances inside the urine.  The reagent tablet is and so placed on top of the absorbed urine and h2o is added to the tablet.  The h2o dissolves the solid diazonium salt and acid in the tablet and so that they run onto the mat.  The reaction of conjugated bilirubin with the diazonium salt in the acrid environment results in the germination of a blue ring around the dissolving tablet.  The sensitvity of the tablet test is 0.05 to 0.one mg/dL, which is about 10 times more sensitive than the dipstick test.  The tablet examination is also more specific than the dipstick test for bilirubin and its primary employ is the detection of false positive dipstick reactions. Since the urine is placed on the mat get-go in the tablet test, abnormal pigments due to medications or blood metabolites tin can exist detected before the chemical reaction ensues.  Other interfering substances are washed through the mat and practice not come into contact with the diazonium salt.  Also, considering the reaction product is blue rather than tan or magenta, fewer interpretation bug are encountered.  Examples of medications that produce false positive dipstick and negative Ictotest results include rifampin, phenazopyridium (Pyridium), and nonsteroidal antiinflammatory agents (etodolac, mefenamic acid and flufenamic acid).

Bilirubin and urobilinogen tests are valuable in detecting hemolysis, hepatic dysfunction, and biliary obstacle.  The results of these two tests should exist interpreted together. Bilirubin is unstable and rapidly decomposes during exposure to light.  False negative reactions are common if urine is not tested before long after collection. Chlorpromazine (Thorazine) and selenium tin can produce faux negative results.

Urobilinogen

Most dipsticks utilise para-dimethylaminobenzaldehyde in a strongly acid medium to test for urobilinogen.  A positive reaction produces a pinkish-ruby-red color. Urobilinogen is usually present in urine at concentrations upward to 1.0 mg/dL. A event of ii.0 mg/dL represents the transition from normal to abnormal.  False positive results tin be caused by medications such as para-aminosalicylic acid, antipyrine, chlorpromazine, phenazopyridine, phenothiazine, sulfadiazine, and sulfonamide.  Loftier nitrite concentrations can cause fake negative reactions.  Pigmented urine can interfere with detection of urobilinogen.

Conjugated bilirubin is normally excreted into the bowel where bacteria metabolize it to urobilinogen.  Urobilinogen is partially reabsorbed from the gut and excreted in the urine.  A positive examination indicates increased bilirubin delivery to the gut.  Hepatitis produces positive urine bilirubin and urobilinogen.  Biliary tract obstacle results in positive urine bilirubin but negative urobilinogen.  Hemolytic anemia causes negative urine bilirubin and positive urobilinogen.

Illness	Urobilinogen	Bilirubin
Healthy	Normal	Negative
Icteric liver illness	Increased	Positive
Biliary obstruction	Absent	Positive
Hemolytic anemia	Increased	Negative

Leukocyte Esterase

Pyuria (the presence of leukocytes in the urine) can be detected using the leukocyte esterase reagent strip examination. The assay is based on the chemi­cal detection of esterases, which are enzymes contained within the azurophilic granules of polymorphonuclear leukocytes.  Esterase level is directly proportional to the number of leukocytes present in a urine sample. The footing of the chemical reaction is the hydrolysis of an ester to form an aromatic alcohol and acid. The aromatic chemical compound combines with a diazonium salt to form an azo-dye that changes to purple.  Colour intensity read at 2 minutes is proportional to the number of granulocytes in a sample.  Positive results are reported semiquantitatively as trace, 1+, 2+, or iii+.  The sensitivity for Multistix reagent strips is five cells per high power field (hpf) to 15 cells/hpf while Chemstrip reagent strips have a sensitivity of 20 leukocytes per uL of urine. Because of this relative insensitivity, the absence of leukocyte esterase does not rule out urinary tract infection (UTI). A positive esterase reaction indicates inflammation secondary to UTI or renal disease.

Esterase activeness from either intact or lysed granulocytes can give a positive result.  Lysed granulocytes may produce credible discrepancies between positive dipstick results and negative microscopic examinations.  Lympho­cytes do not produce a positive reaction.  Other sources of esterase such as eosinophils, Trichomonas, or epithelial cells in vaginal fluid may give faux positive results.  Oxidizing agents such as bleach or colored substances tin produce false positives.

False negative results can be caused by high concentrations of ascorbic acid (vitamin C), albumin or other proteins (>500mg/dL), glucose (>3000 mg/dL), or ketones. Urine with high specific gravity tin cause a simulated negative reaction because enzyme is not every bit readily released from crenated white blood cells.  These samples should be examined microscopically so as non to miss clinically significant pyuria.  WBC clumping may foreclose dispersion of leukocyte esterase and cause a false negative result.  Outdated or deteriorated dipsticks are another cause of imitation-negative results.

Doxycycline, gentamicin and some cephalosporins reduce the reactivity of leukocyte esterase and produce false negative results.  Conversely, imipenem, meropenem, and clavulanic acid can crusade false positive leukocyte esterase reactions.

About studies comparison the sensitivity of nitrite and leukocyte esterase tests compared to urine culture have demonstrated that leukocyte esterase is a more sensitive indicator of UTI than nitrite.

Nitrite

The nitrite test is a rapid, indirect method for detec­ting bacteriuria.  The reaction principle is based on bacterial reduction of dietary nitrate, which is normally present in urine, to nitrite, which is non nor­mally present. Nitrite reacts with para-arsanilic acid on the dipstick to course a diazonium compound that reacts with a benoquinoline to form a pink color. Many of the bacteria that cause UTIs have the ability to reduce nitrate, including Escherichia coli, Klebsiella, Pseudomonas, Enterobacter, and Citrobacter. The optimal specimen is a freshly voided, kickoff morning urine that has been retained in the bladder a minimum of 4 hours, per­mitting adequate time for conversion of nitrate into nitrite by the bacterial enzymes.  A positive nitrite test result indicates UTI with significant bacteri­uria. Examination sensitivity has been standardized to correspond to a urine bac­terial count of 100,000 colony forming units/mL (CFU/mL).  Color intensity is not proportional to the degree of bacteriuria; results are just reported equally positive or negative.

False positive results can exist caused by colored substances in the urine (due east.g. phenazopyridine) and prolonged specimen storage at room temper­ature that allows proliferation of contaminating bacteria.  If uri­nalysis cannot be washed within two hours after drove, specimens should be refrigerated to forbid bacterial growth.

False-negative nitrite results can occur fifty-fifty in the presence of signif­icant bacteriuria due to a number of possible factors.  The causative organisms may lack the reductase enzyme needed to convert nitrate to nitrite. For example, both yeast and gram positive bacteria are reductase negative. Malnourished patients and patients receiving intravenous feed­ing may have insufficient dietary nitrate to promote the chemic reaction.  The duration of urine retention in the bladder may be too short (<4 hours) to facilitate nitrate reduction.  Previous antimicrobial therapy may inhibit bacterial metabolism.  In the presence of high numbers of bacteria, nitrite may be farther reduced to nitrogen, which is not detected.  High concentrations of ascorbic acrid or urobilinogen can inhibit the chemic reaction. Of course, outdated or deteriorated dipsticks tin can also yield faux-negatives.  Microscopic examination of urine sediment or urine culture should be performed, even with negative nitrite, when clinical symptoms suggest UTI.

Vitamin C is a strong reducing amanuensis and interferes with a number of dipstick tests.  An evaluation of 4379 urinalysis specimens from outpatients in a unmarried laboratory revealed that 23% contained measurable vitamin C. An oral dose of 100 mg of vitamin C caused falsely negative dipstick tests for blood, glucose and leukocyte esterase in urine samples tested within 4 hours of ingestion.  Vitamin C consumption is a probable cause of discrepancies betwixt urine dipstick and microscopic analysis.

Specific Gravity

The specific gravity of a solution is the ratio of the mass per unit of measurement volume of the solution to the mass per unit volume of distilled water. It is a relative measure past weight of the corporeality of dissolved urinary solutes. All urine contains some solutes and will always take a specific gravity college than pure water (1.000).  Normally, an adult should be able to concentrate the urine to a specific gravity of 1.016 to 1.022.  A first morning time urine with a specific gravity of 1.023 or higher later overnight fluid impecuniousness indicates normal renal concentrating capacity.

The dipstick specific gravity test is based on the apparent pKa change of polyelectrolytes in relation to ionic concentration. In the presence of an indicator, colors range from deep blueish-greenish in urine of low ionic concentration through greenish and yellow-green in urines of increasing ionic concentration.

Diabetes mellitus is associated with increased urinary book and elevated specific gravity due to urinary glucose, which increases the solute content.

Diabetes insipidus results in a big urinary volume with depression specific gravity.  Hyposthenuria means a persistently low urine specific gravity  of <i.007.

Renal tubular disease is often manifested early by a loss of concentrating capacity of the kidneys; specific gravity is <1.018. Afterwards in the disease process, the capacity to dilute the urine is lost and the patient can just produce isothenuric urine with a fixed specific gravity of 1.010.

The kidneys cannot concentrate urine to a specific gravity of >one.035.  Specific gravity readings greater than i.035 by refractometer, accompanied by normal specific gravity past reagent strips, ordinarily incorporate higher molecular weight solutes such as glucose, protein, radiopaque dissimilarity media or drugs.  Organic iodides in contrast media such as meglumine diatrizoate (Renograffin, Hypaque) may be seen in the urine sediment for a brief time afterwards injection of the dye.  The crystals resemble cholesterol crystals.

Dipstick Reference Range

Assay	Reference Value	If positive, reported as:
Specific gravity	one.003 - ane.030	Number
Claret	Negative	Pocket-size, moderate, large
Ketones	Negative	Modest, moderate, large
Glucose	Negative	100, 250, 500, m, >m mg/dL
Protein	Negative	thirty, 100, 300, >2000 mg/dL
pH	4.v - 8.0	Number
Leukocyte esterase	Negative	Positive

Microscopic Exam

A microscopic test is performed if claret, protein, or leukocyte esterase results are aberrant or if a microscopic exam is specifically requested. The urine is centrifuged and examined microscopically for WBC, RBC, crystals, casts, leaner and yeast. Both dipstick and microscopic exam should exist performed for patient populations with a high incidence of genitourinary tract disease.

Microscopic urinalysis cannot exist completely eliminated considering multiple clinically significant findings can only be detected by examining urine sediment directly. For example, a positive dipstick reaction for blood does non distinguish betwixt ruddy cells, hemoglobin, or casts.  Besides, a positive leukocyte esterase reaction does non distinguish between gratuitous WBCs that occur in cystitis, from WBC casts that are feature of pyelonephritis.  Microscopy tin detect several other clinically pregnant abnormalities that are not detected by dipsticks including renal tubular epithelial cells and casts, fat casts, oval fat bodies, crystalline casts, and crystals.

Cells

Epithelial cells

The urinary tract is lined by epithelial cells, including squamous, transitional and renal tubular cells. Squamous epithelial cells line the bladder trigone, urethra and vagina. They are large cells, measuring 30 to 50 um in bore, with a unmarried small round nucleus. They may appear round, polygonal or rectangular in shape with curled edges. Their presence in urine has no clinical significance.

Transitional cells line the urinary tract from the renal pelvis to the trigone of the float in females and the first part of the urethra in males. They are 4 to vi times larger than a red claret jail cell, announced spherical or polyhedral in shape and have a larger circular or oval nucleus. Minor numbers of transitional cells have no clinical significance. Large clusters are seen after bladder catheterization or washing. Large number transitional cells with dysplastic nuclei might be indicative of malignancy.

Renal tubular epithelial cells line the proximal and distal convoluted tubules and collecting ducts of the kidney.  They are 3 to 5 times larger than a cherry-red blood jail cell and announced elongated and polyhedral.  One side often appears flattened and microvilli may be seen. Their cytoplasm is granulated and they have a single eccentric nucleus. A small number of renal tubular cells is not clinically significant. The presence of more than 15 cells in ten high power fields suggests agile renal disease or injury. Examples include acute tubular necrosis, drug or metal toxicity, infections and renal transplant rejection.

Renal tubular epithelial cells filled with fat droplets are chosen oval fat bodies and are detected in the nephrotic syndrome.  Renal tubular cells may besides accumulate hemosiderin, which appears as coarse yellowish-brown cytoplasmic granules. The granules stain blue with Prussian blue. They are detectable ii to 3 days after intravascular hemolysis.

Blood Cells

Nether high power, unstained RBCs appear as stake, homogeneous, biconcave discs with no nucleus. They vary somewhat in size, but are usually about 7 microns in diameter. Cerise cells tumble when the fluid on the slide is set in move.  If the specimen is not fresh when it is examined, the cells volition appear as faint, colorless circles (shadow or ghost cells) because the hemoglobin has leached out of the cell. In dilute urine, red cells absorb water, swell and lyse, releasing their hemoglobin and leaving simply ghost cells. In urine with a very high specific gravity, the reddish cells become crenated, which may announced every bit spikes in the cell. In urine with a depression specific gravity or with extreme pH, the cells may be lysed.

Red blood cells must exist distinguished from yeast and fatty droplets. Yeast often exhibit budding and fat aerosol are highly refractile. Positive identification of red blood cells can be accomplished by calculation 2% acerb acid to the urine sediment, which lyses red blood cells.

Cypher to half dozen RBCs/hpf is considered to be within normal limits. Physiological increases in the number of RBCs in urine may occur following vigorous do or fever without indicating significant urinary tract disease. Presence of large numbers of reddish cells (smoky urine) indicates bleeding into the urinary tract, anywhere from the kidney to the urethra. This may be due to several causes including urinary tract infection, tumor in the kidney or urinary tract, calculi or urinary tract stones, derangements of blood clotting, trauma and renal disease such every bit glomerulonephritis. The presence of blood-red cells without the presence of protein or casts suggests that the haemorrhage occurred distal to the kidney.

When RBCs traverse an injured glomerular capillary they may undergo a change in morphology from biconcave disc to dysmorphic. Proliferative glomerulonephritis is suggested when more than than 15% of urine RBCs are dysmorphic (specificity 85%, sensitivity 47%) or when acanthocytes constitute at least 10% of visualized RBCs (specificity 85%, sensitivity 42%). The absenteeism of dysmorphic RBCs or acanthocytes does not rule out proliferative glomerulonephritis  because sensitivities are but 47% and 42%, respectively.

WBCs (leukocytes) appear as round granular spheres well-nigh 14 μm in diameter (about twice the size of a red prison cell) and have a nucleus. Some WBCs in hypotonic urine appear larger because they have captivated h2o and the cytoplasmic granules showroom Brownian movement. These cells are chosen glitter cells.

A few WBCs can exist plant in normal centrifuged urine. Pyuria mostly indicates an infectious or inflammatory process somewhere in the kidney (pyelonephritis), bladder (cystitis) or urethra (urethritis). Clumps of WBCs should be noted because they can affect urine white jail cell count.

The presence of increased numbers of eosinophils may exist indicative of drug-induced interstitial nephritis. However, special staining procedures using Hansel's stain must be performed earlier the eosinophils tin exist reliably identified.

Lymphocytes in the urine cannot be clearly identified without the use of a Wright'due south or Papanicolaou stain. The presence of lymphocytes may be seen in renal transplant rejection, inflammatory processes, and other disorders.

Casts

Urinary casts are formed in the distal convoluted tubule or the collecting duct of the kidney. Cast formation increases with stasis, increased protein excretion and lower pH. Three categories of casts may be seen: acellular, cellular, and mixed. The type and number of casts seen per low power field is reported.

Hyaline casts are composed primarily of a mucoprotein, which is called Tamm-Horsfall protein, and is secreted by cells lining the distal convoluted tubules. The factors that favor protein cast formation are low menses rate, high salt concentration, and depression pH because these weather favor poly peptide atmospheric precipitation. A few hyaline casts are normal, but all other casts need to be evaluated. Cast width is described as narrow (ane to two RBCs in width), medium broad (three to four RBCs in width), or broad (five RBCs in width). Casts that form in the collecting tubules tend to be very broad and usually indicate stop stage renal disease.

Pigment casts are hyaline casts with captivated pigments such equally bile or hemoglobin, are yellow to brown in color, and may have a smoothen or granular surface. These casts may be seen in patients with viral hepatitis as well equally multiple myeloma and those patients with renal amyloidosis.

Fatty casts form when fatty from lipid-laden tubular cells is incorporated into the cast.  They incorporate yellowish-tan fat globules on their surface. They usually indicate the nephrotic syndrome.

RBC casts incorporate numerous orange-scarlet erythrocytes or unpigmented ghost RBC embedded within a hyaline matrix. The unpigmented form is more than frequent and can frequently be recognized by its hemoglobin pigmentation. RBC casts are usually accompanied by the presence of free RBCs in the sediment. RBC casts are frequently establish in glomerulonephritis. Occasionally, they may be seen in individuals playing contact sports. In the latter situation, the urine usually returns to normal within 24 to 48 hours.

The typical renal tubular cell casts are frequently described as hyaline matrix casts showing two rows of well-delimited tubular cells. However, the two row criterion is not reliable because WBC casts tin also have this appearance.  Renal tubular cells are difficult to identify in cellular casts. The cells are elongated or columnar and have large eccentric nuclei with sparse granular cytoplasm. Their presence indicates renal tubular harm.

When cellular casts remain in the nephrons for some time before being flushed into the float, the cells may degenerate to a coarsely granular bandage, later to a finely granular cast, and eventually, to a waxy cast. Granular and waxy casts are believed to be derived from renal tubular casts.  Granular casts are non-specific and may exist nowadays in a variety of kidney disorders. Waxy casts are associated with advanced kidney illness and chronic kidney failure. They are opaque, like shooting fish in a barrel to run into and accept cleaved off ends, besides equally notched parallel margins.

Granular casts are semitransparent cylinders containing fine or coarse granules. Distinction between finely and coarsely granular casts is not clinically important. The granules are the result of cellular breakup and protein aggregation. They have little clinical significance, unless present in very big numbers. Increased numbers are seen subsequently strenuous do, fever, dehydration and stress. Large numbers are associated with renal glomerular or tubular affliction.

Crystals

Calcium oxalate crystals occur as the mutual dehydrate class and the less common monohydrate form. The dehydrate class appears as small colorless octahedrons. The monohydrate grade is dumbbell-shaped or ovoid rectangles. Both forms are found in acid or neutral urine. They are seen more ordinarily in urine in individuals who eat foods rich in oxalic acide such equally tomatoes, asparagus, oranges and rhubarb. Large numbers are associated with kidney stone formation, severe chronic renal affliction, ethylene glycol poisoning and methoxyflurane toxicity. They may also be increased in patients with Crohn'southward illness and later small bowel resection.

Triple phosphate (ammonium magnesium phosphate) crystals differ from calcium oxalate in that they are colorless 3 to 6 sided prisms, called coffin lids. Occasionally, sheets, flakes, apartment or fern foliage forms are seen. Their formation increases if urine is left at room temperature. They may develop a feathery advent as they breakup. Triple phosphate crystals occur in neutral to alkali metal urine and do not accept clinical significance.

Calcium pyrophosphate dehydrate crystals appear as rhomboids, rods or rectangles and tend to exist pocket-sized, measuring between 1 and xx um. They are smaller than cholesterol crystals and lack the corner notch. They differ from monosodium urate in that they form very modest rhomboids, brusk rods, or rectangles. With polarized calorie-free, they are weakly birefringent and appear yellow when aligned with the compensator axis. This polarization pattern is the contrary of monosodium urate crystals.  They are associated with degenerative arthritis.

Uric acid crystals are simply seen in acid urine and take a wide diverseness of forms including rhombic, four-sided plates, rosettes, wedges and lemon shapes. Needle shaped crystals of monosodium urate are rarely seen in urine. They commonly announced yellow or red-brown and form in acid urine. Uric acid crystals are considered to exist a normal constituent of urine. Big numbers may exist seen with gout, increased cell turnover associated with chemotherapy and Lesch Nyhan syndrome.

Cholesterol crystals normally class colorless plates with a notched corner.  Cholesterol crystals are rarely seen in urine from patients with normal renal office. Cholesterol crystals, fatty casts and fat droplets are virtually commonly seen in patients with nephrotic syndrome.

Tyrosine crystals are rarely seen.  They class clusters of needles that are colorless or black in acidic urine. Tyrosinuria accompanies liver disease or hereditary hypertyrosinemia.

Artifacts

Mucus is a normal finding in urine sediment and is more frequently seen in specimens from females. Fungus forms colorless threads or long ribbon-like structures with undefined edges and pointed or frayed ends. Mucus threads may be confused with hyaline casts.

The presence of contaminants such every bit fiber indicates poor collection technique or contamination from article of clothing or diapers. They tin also occur as a effect of fecal contamination. Fibers need to be distinguished from casts. Fibers have dark edges and a apartment appearance. Fibers are usually longer and more than refractile than casts.  Unlike casts, fibers polarize brightly.

Corpora amylacea are pocket-sized, amorphous nodules or concretions that accumulate in the prostate gland with age. They can exist seen in the urine of older men with benign prostatic enlargement, likewise as in urine specimens obtained after prostatic manipulation.

Starch granules are a frequent contaminant in urine due to contamination with the pulverisation used in examination or surgical gloves. They appear spherical or oval and are highly refractile. They typically have a dimpled or indented centre that resembles a maltese cross. They may be several times larger than a crimson blood jail cell.  They can be dislocated with crystals or parasites.

Exogenous fatty cloth from creams or lubricants can contaminate urine and appear as fat globules. They are non associated with fat casts. Oil droplets are round like a ball and can easily be mistaken for red blood cells.

Radiographic contrast material may produce flat colorless crystals, simply is commonly associated with very high specific gravity.

Sperm may be seen in male urine or female urine that has been contaminated with vaginal secretions.

Microorganisms

Trichomoniasis is 1 of the most common sexually transmitted diseases, mainly affecting sexually active women. T. vaginalis appears in urine as a result of vaginal contagion. Ofttimes the organism is motile and will swim rapidly across the microscope slide.

Yeast are ovoid, colorless and accept smoothen thick walls that give them a refractile appearance. They may bear witness branching, or hyphae. Yeast are smaller than ruddy blood cells, measuring only 2 mm in diameter. Yeast in urine may be a contaminant from air or skin or may be due to a urinary tract infection. Large numbers of white blood cells will besides be present in the latter case. The nearly important blazon is Candida. Infections are about common in diabetic and immunocompromised patients.

Pinworms may be seen in urine, especially if the urine was obtained very early in the morning, because the adult pinworm commonly deposits its eggs in the perianal area during the night. They can also be seen in urine specimens with fecal contamination.

Filariasis is a term applied to several parasitic infections caused by microscopic, thread-like worms (east.g., Loa loa, Onchocerca volvulus). Typically, the adult worms live in the man lymph organization. During their life cycle, the adults produce microfilariae measuring 250 to 300 μm past 6 to eight μm, which are sheathed and demonstrate diurnal periodicity (organisms broadcast in the bloodstream during the day and are not-circulating in the dark). Microfilariae accept been recovered from urine, every bit well as spinal fluid and sputum.

Schistosomiasis (bilharziasis) is ane of the globe'due south well-nigh mutual parasitic infections. The life bike of the organism has been extensively studied. Eggs from carrion, when deposited in a fresh water site, hatch and infect an appropriate snail host. Later on about four weeks, cercarial forms sally from the snail and swim in search of the side by side host, humans. After skin penetration, the organisms enter the host's bloodstream, pass through the lungs, and lodge as adult forms in the portal-mesenteric vascular organization. The epitome is of S. haematobium, whose eggs can be institute in urine. The eggs are laid in the venous system of the float.

Specimen Requirement

Specimen requirement is 10 mL from a random urine collection.  A first morn void (overnight) specimen is preferred because it is more full-bodied and can exist assumed to have been in the bladder for a number of hours. A dilute specimen is more probable to yield a false negative upshot.

Urine should exist tested equally soon as possible after drove. Some determinations such as urobilinogen, bilirubin and pH are only valid if obtained on a fresh specimen. Prolonged length of fourth dimension between specimen drove and analysis tin result in fake-positive urine nitrites and false-negative glucoses. Besides, bacterial overgrowth in not-preserved, non-refrigerated specimens leads to false-positive or contaminated urine culture results. Bacterial growth, cellular deposition, atmospheric precipitation of amorphous material, and increasing pH due to urease producing bacteria adversely bear upon protein measurements.  A urine more than 24 hours old, even if refrigerated should non exist tested. If urine has been refrigerated, it should exist immune to return to room temperature earlier testing.  Refrigeration may cause an increase in specific gravity and precipitation of amorphous phosphates and urates. Glucose sensitivity is adversely affected by not testing at room temperature.

A closed urine transport organisation with integrated transfer tubes that contains preservative decreases the potential for bacterial contamination. This system allows for urine culture set-upwardly up to 48 hours after collection and urinalysis up to 72 hours later drove.

Microscopic Reference Range

Microscopic examination is considered normal if all of the following criteria are met:

• 0 to 6 erythrocytes per loftier power field
• 0 to 6 leukocytes per high ability field
• <3 hyaline or <1 granular cast per low ability field
• Absence of any other casts
• Absence of significant crystals (i.e. cystine, leucine, tyrosine)

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Source: http://www.clinlabnavigator.com/urinalysis.html

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