Used most frequently - screening test
Can also be utilized - monitoring response to treatment
- to note progression of a disease
Suspected urinary tract infection
Suspected acute glomerulonephritis
Suspected acute interstitial nephritis
Unexplained acute or chronic renal failure
Haematuria (with or without proteinuria) on urine dipstick
Suspected urinary tract malignancy.
1. First morning, midstream: Preferred for routine urine examination.
2. Random, midstream: Routine urine examination.
3. First morning, midstream, clean catch: Bacteriological
5. Postprandial: Estimation of glucose, urobilinogen
6. 24-hour: Quantitative estimation of proteins or hormones.
7. Catheterised: Bacteriological examination in infants, bedridden patients,
and in obstruction of urinary tract.
8. Plastic bag (e.g. colostomy bag) tied around genitals: Infants; incontinent
Midstream clean catch early morning sample is preferred
for microscopic examination of sediment
- most concentrated
- highest concentration of cells
- high pH and better preservation of cellular architecture.
1. Midstream specimen:
◦ After voiding initial half of urine , a part of urine is collected in the
◦ First half of stream serves to flush out contaminating cells and
microbes from urethra and perineum.
◦ Subsequent stream is collected which is from the urinary bladder.
2. Clean-catch specimen:
◦ In men, glans penis is sufficiently exposed and cleaned with soap and
◦ In women urethral opening should be exposed, washed with soapy
cotton balls, rinsed with water-saturated cotton
◦ holding the labia apart, the initial urine is allowed to pass and the
remaining is voided into the bottle (amount 20-100 ml).
◦ This method avoids contamination of urine with the vaginal fluids.
1. Catheter specimen:
◦ This is used for bacteriological study or culture in bedridden, ill
patients or in patients with obstruction of urinary tract.
◦ It is usually avoided in ambulatory patients since it carries the risk of
introduction of infection.
◦ In infants, a clean plastic bag can be attached around the baby’s
genitalia and left in place for some time.
◦ For bacteriologic examination, urine is aspirated from bladder by
passing a needle just abovesymphysis pubis.
Collection for routine urinalysis
For routine examination of urine, a wide-mouthed glass bottle of 20-
30 ml capacity, which is dry, chemically clean, leak proof, and with a
tight fitting stopper is used.
About 15 ml of midstream sample is cleanly collected.
Best - immediate, analysis within 2 hours
There is no good substitute for immediate examination. Preservatives
should be avoided in-
Reagent strip techniques
Chemical tests for protein
If delay ---- refrigeration- upto 8hrs(4-6 C).
Preservatives for 24 hr sample: for several days
Formalin- for sediments ; interferes with sugar.
Thymol - for sediments; interferes with sugar, proteins, acetone.inhibits bacteria
Toluene –forms thin film, used for measurement of chemicals, interferes with
Sod azide- research purpose, prevents bacterial growth
Sod fluoride- preserves glucose in 24 hrs urine, xylose is also preserved.
Hydrochloric acid – 24 hr urine sample for adrenaline, noradrenaline, and steroids
1. Increase in pH due to production of ammonia from urea by urease-
2. Formation of crystals due to precipitation of phosphates and calcium
3. Loss of ketone bodies, since they are volatile.
4. Decrease in glucose due to glycolysis and utilization of glucose by cells
5. Oxidation of bilirubin to biliverdin causing false negative test for
6. Oxidation of urobilinogen to urobilin causing false negative test for
7. Bacterial proliferation
8. Disintegration of cellular elements, especially in alkaline and hypotonic
5. Specific gravity
The average 24 hr urinary output in adults is 600-2000 ml.
The volume varies with fluid intake, diet and climate.
Polyuria - urinary volume >2000ml/24 hrs
◦ Diabetes mellitus, diabetes insipidus, chronic renal failure and diuretic
Oliguria – urinary volume <400ml/24 hrs
◦ Febrile states, acute glomerulonephritis, congestive cardiac failure or
Anuria – urinary output <100ml/24 hrs or complete cessation of
◦ Acute tubular necrosis, acute glomerulonephritis and complete urinary
Normal color in a fresh state is pale yellow or amber
due to urochromes.
Depending on state of hydration, urine may be
colorless (over hydration) or dark yellow (dehydration)
Normal freshly voided urine is clear in appearance.
Foamy urine occurs in presence of excess proteins
Freshly voided urine has typical aromatic odor due to
volatile organic acids.
◦ Fruity – ketoacidosis, starvation
◦ Mousy or musty – phenylketonuria
◦ Fishy – UTI with proteus, tyrosinemia
◦ Ammoniacal – UTI with E coli, old standing urine(formation of
ammonia occurs when urea is decomposed by bacteria)
◦ Foul – UTI
◦ Sulfurous – cystinuria
Normal pH range is 4.6 to 8.0 (average 6.0 or slightly
Urine pH depends on- diet, acid base balance, water
balance, and renal tubular function.
On standing, urine becomes alkaline because of loss of
carbon dioxide and production of ammonia from urea.
Therefore, for correct estimation of pH, fresh urine
should be examined.
1. Litmus paper test: A small
strip of litmus paper is
dipped in urine and any
color change is noted. If blue
litmus paper turns red, it
indicates acid urine. If red
paper turns blue, it indicates
2. Reagent strip test: The test
area contains polyionic
polymer bound to H+; on
reaction with cations in
urine, H+ is released causing
change in color of the pH-
1. pH indicator paper:
◦ Reagent area (which is impregnated with bromothymol
blue and methyl red) of indicator paper strip is dipped in
urine sample and the color change is compared with the
color guide provided.
◦ Approximate pH is obtained.
2. pH meter:
◦ An electrode of pH meter is dipped in urine sample and pH
is read off directly from the digital display.
Relative mass density.
Depends on amount of solutes in solution.
It is basically a comparison of density of urine against the
density of distilled water at a particular temperature.
Specific gravity of distilled water is 1.000.
Normal SG of urine is 1.003 to 1.030 and depends on the
state of hydration.
SG of urine is a measure of concentrating ability of kidneys
and is determined to get information about this tubular
Take 2/3 of urinometer container with urine
Allow the urinometer to float into the urine
Read the graduation at the lowest level of
Correction of temperature & albumin is a must.
Urinometer is calibrated at 15or 200c
So for every 3oc increase/decrease -
For 1gm/dl of albumin/glucose- substract
2. Refractometer method:
Refractometer measures the refractive index of the total
Higher the concentration of total dissolved solids, higher
the refractive index.
Extent of refraction of a beam of light passed through
urine is a measure of solute concentration, and thus of
3. Reagent strip method:
Reagent strip measures the concentration of ions in
urine, which correlates with SG.
Depending on the ionic strength of urine, a
polyelectrolyte will ionize in proportion.
This causes a change in color of pH indicator
High specific gravity
Diabetes insipidus (SG
Chronic renal failure (low
and fixed SG at 1.010 due
to loss of concentrating
ability of tubules)
Compulsive water drinking.
Fixed specific gravity (isosthenuria)=1.010
Seen in chronic renal disease when kidney has lost the ability to
concentrate or dilute
Bile pigments (Bilirubin)
Chemical examination for significant bacteriuria
Normal urine contains small amount of
protein:Usually upto 150mg/24 hrs
These include proteins from
◦ Plasma ( albumin)
◦ Protein from urinary tract (tamm-horsfall protein,
secretory IgA, proteins from tubular epithelial cells,
leukocytes and other desquamated cells)
Excretion of more than this level >150mg/24hrs
Glomerular diseases damage glomerular basement
membrane (increased permeability) but tubular
function is normal
◦ selective proteinuria---chiefly albumin
◦ nonselective proteinuria
Causes : acute glomerulonephritis and nephrotic
◦ When glomeruli can retain larger molecular weight
proteins but allow passage of comparatively lower
molecular weight proteins ( albumin and transferrin)
◦ Occurs in early stages of disease
Non selective proteinuria
◦ With further glomerular damage, this selectivity is lost
and larger molecular weight proteins (ƴ globulins) are
also excreted along with albumin
Both distinguished by urine protein
◦ In selective proteinuria, albumin and transferrin bands
◦ In non selective – pattern resembles that of serum
Normally, glomerular membrane although
impermeable to high molecular weight proteins, allows
ready passage to low molecular weight proteins like
◦ β2 microglobulin, retinol binding protein, lysozyme, α1-
microglobulin and free immunoglobulin light chains.
These low molecular weight proteins are readily
reabsorbed by proximal renal tubules.
In diseases involving mainly tubules, these proteins are
excreted in urine while albumin excretion is minimal.
◦ Acute and chronic pyelonephritis, Tb of
kidney ,Heavy metal poisoning, Interstitial nephritis,
Cystinosis, Fanconi syndrome, Rejection of kidney
Purely tubular proteinuria cant be detected by
reagent strip test – detected by heat and
acetic acid test and sulphosalicylic acid test
When concentration of a low molecular weight protein
rises in the plasma, it overflows from plasma into the
Such proteins are
◦ immunoglobulin light chains
◦ bence jones proteins (plasma cell dyscrasias)
◦ hemoglobin (intravascular hemolysis )
◦ myoglobin (skeletal muscle trauma )
◦ lysozyme ( AML M4 or M5)
Alteration of blood flow through glomeruli causes
increased filteration of proteins.
Protein excretion is transient
◦ High fever
◦ Heavy exercise
◦ Exposure to cold
Post renal proteinuria
Inflammation or neoplastic conditions in renal pelvis,
ureter, bladder, prostate or urethra
Postural ( orthostatic proteinuria)
When subject is standing or ambulatory, but is absent
in recumbant position.
Seen in adolescents
Due to lordotic posture that causes inferior venacaval
compression between liver and vertebral column.
Periodic testing is done to rule out renal diseases.
1st morning urine after rising is negative, while another
sample collected after patient performs activities is
Test – Heat & acetic acid test
Principle-proteins are denatured & coagulated on
heating to give white cloud precipitate.
Method-take 2/3 of test tube with urine, heat
only the upper part keeping lower part as control.
Presence of phosphates,
gives a white cloud
formation. Add acetic
acid 1-2 drops, if the
cloud persists it indicates
it is protein(acetic acid
Reagent strip test
Principle- the reagent area of the strip is coated with an
bromophenol blue indicator and buffered to an acidic pH which
changes color in presence of proteins. Called as protein error of
When dye gets adsorbed to protein, there is change in ionization
– change in color of indicator.
Intensity of color directly proportional to concentration of
False negative- alkaline urine, gross hematuria, contamination
with vaginal secretions
Sulphosalicylic acid test –
Principle- addition of sulphosalicylic acid to the urine
causes formation of a white precipitate if proteins are
present (proteins are denatured by organic acids and
precipitate out of the solution).
False positive – gross hematuria, highly concentrated
urine, radiographic contrast media, excess uric acid,
tolbutamide, sulphonamides, salicylates and penicillin.
False negatives- very dilute urine.
1. Diagnosis of nephrotic syndrome
2. Detection of microalbuminuria or early diabetic nephropathy
3. Follow response to therapy in renal diseases
◦ >1500mg/day – glomerular diseases
◦ >3500mg/day – nephrotic range proteinuria
◦ <1500mg/day- tubular, hemodynamic and post renal diseases.
Two methods –
1. Quantitative estimation of proteins in a 24 hour
◦ Esbach’s albuminometer method
◦ Turbidimetric method
◦ Biuret reaction
◦ Immunologic method
2. Estimation of protein/creatinine ratio in a
random urine sample.
◦ Normal protein/creatinine ratio - <0.2
◦ Low grade proteinuria – 0.2-1.0
◦ Moderate- 1.0- 3.5
◦ Nephrotic range proteinuria - >3.5
Defined as urinary excretion of 30-
300mg/24 hrs of albumin in urine
◦ Earliest sign of renal damage in diabetes mellitus
◦ Independent risk factor for cardiovascular disease
in diabetes mellitus.
Detection of microalbuminuria
Cannot be detected by rutine tests for proteinuria.
1. Measurement of albumin-creatinine ratio in a random
2. Measurement of albumin in an early morning or random
3. Measurement of albumin in 24 hr sample.
4. Test strips
5. Exact quantitation by radioimmunoassay or enzyme linked
Presence of bence jones protein (with unusual
thermosolubility) in the urine, usually indicative of a
neoplastic process such as multiple myeloma,
amyloidosis or Waldenstrom's macroglobulinaemia.
The classic method of identifying bence-jones
protein is precipitation from urine in the range of
4o-60 c. It goes into solution at temprature above or
below this range.
Electrophoresis- The presence of B.J protein & clonal
production of Ig is indicated by single sharp peak in the
globulin region .
Heat test- If albumin & B.J protein are present,boil the urine
to 100 degree & filter ppt - albumin will be filtered out , take
the rest urine heat it to 45-60 deg - B.J protein will ppt then
dissolve on boiling
False positive– other protein e.g globulin are ppted by heat
False negative – when B.J protein is too conc - ppt does not
resolve on boiling
All the glucose filtered by the glomeruli is reabsorbed by the
proximal renal tubules and returned to circulation.
Normally, very small amount of glucose is excreted in the urine
(<500mg/24 hrs or <15md/dl)- cannot be detected by routine
Presence of detectable amount of glucose in urine is called as
glucosuria or glycosuria.
Glycosuria results when filtered glucose load exceeds the
capacity of renal tubular reabsorption.
1. Glycosuria with hyperglycemia
◦ Endocrine diseases- Diabetes mellitus,acromegaly, cushing’s
disease, hyperthyroidism, pancreatic disease
◦ Non-endocrine diseases- CNS, liver disorders
◦ Drugs- adrenocorticotropic hormones, corticosteroids,
◦ Alimentary glycosuria (lag storage glycosuria)
2. Glycosuria without hyperglycemia
◦ Renal glycosuria- benign condition in which renal threshold is
set below 180mg/dl but glucose tolerance is normal.
◦ other conditions where glycosuria occurs with blood glucose
Renal tubular diseases like fanconi syndrome and toxic trenal
Test- copper reduction methods
1. Benedict’s qualitative test-
Cupric ions (blue)+ sugar cuprous oxide(red color) +cuprous hydroxide ( yellow)
Method- take 5ml of benedict’s reagent in a test tube, add 0.5
ml of urine and mix well. Boil over flame for 2 min. allow to
cool. Note change in color
Sensitivity – 200 mg/dl of reducing agent in urine
Alkali & heat
This test is not specific for glucose
◦ Other carbohydrates like- lactose, fructose, galactose,
◦ Metabolites like- glucuronic acid, homogentesic acid, uric acid,
◦ Drugs like ascorbic acid, salicylates, penicillin, streptomycin,
isoniazid, para-aminosalicylic acid, nalidixic acid
2. Clinitest tablet method
◦ Modified form of benedict’s test in which reagents are in
form of tablet form
Other test- Reagent strip method (sensitivity –
Principle- glucose oxidase- peroxidase reaction
Glucose + oxygen (from air) gluconic acid + hydrogen peroxide
More sensitive than benedicts as specific for glucose
False positive- presence of oxidizing agents like bleach or
False negative- large amounts of ketones, salicylates, ascorbic
acid, several E. coli infections
Glucose oxidase + chromogen in
presence of peroxidase
Oxidised chromogen (blue) + water
Excretion of ketone bodies (acetoacetic acid,β hydroxy
butyric acid and acetone) in urine is called ketonuria
If energy requirements cannot be met by metabolism of
glucose, then energy is derived from breakdown of fats-
formation of ketone bodies
◦ Decreased utilization of carbohydrates
Uncontrolled diabetes mellitus with ketoacidosis
Glycogen storage disorders
◦ Decreased availability of carbohydrates in diet
Starvation, persistent vomiting, weight reduction programs
◦ Increased metabolic needs
Fever in children, severe thyrotoxicosis, pregnancy, PEM
1. Rothera’s test – ( classic
Principle- acetoacetic acid or
acetone reacts with nitroprusside
in alkaline solution to form
purple colored complex.
Take 5 ml urine in a test tube and
saturate with ammonium
sulphate. Add a crystal of sodium
nitroprusside and mix well.
Slowly run along the side of test
tube, liquor ammonia to form a
False positive- L-dopa in urine
and in phenylketonuria
Sensitivity- 1-1.5mg/dl of
acetoacetate and 10-25mg/dl of
2. Acetest tablet test-
◦ Rothera’s test in the form of a tablet.
◦ Acetest tablet consist of sodium nitroprusside, glycine
and an alkaline buffer.
◦ A purple lavender discoloration of tablet indicates
presence of acetoacetate or acetone (>5mg/dl).
◦ More sensitive than reagent strip test
3. Ferric chloride test (gerhadt’s test)
◦ Addition of 10% ferric chloride solution to urine causes
solution to become reddish or purplish if acetoacetic acid
4. Reagent strip test
◦ Modification of nitroprusside test
◦ Sensitive for 5-10 mg/dl of acetoacetate
The presence of abnormal number of intact
red cells in urine is called hematuria.
1. Diseases of urinary tract –
1. Glomerular diseases
2. Non glomerular diseases
2. Hematological conditions-
Coagulation disorders , sickle cell anemia
Tests for detection
1. Microscopic examination of urinary sediment
2. Chemical tests-
◦ These tests detect both intracellular and extracellular
hemoglobin ( intact and lysed red cells) as well as
◦ Principle –
◦ Heme proteins in hemoglobin act as peroxidase , which
reduces hydrogen peroxide to water.
◦ This process needs a hydrogen donor (benzidine,
orthotoluidine or guaiac).
◦ Oxidation of hydrogen donor leads to development of color.
◦ Intensity of color development is proportional to amount of
Benzidine test –
◦ Make saturated solution of benzidine in glacial acetic acid. Mix
1ml of this solution with 1 ml of hydrogen peroxide in a test
tube. Add 2ml of urine. If green or blue color develops within
5 min, the test is positive.
Reagent strip test- uses chromogens- o-toluidine.
False positive- contamination of urine by oxidizing
agents or microbial peroxidase in UTI
False negative- presence of a reducing agent like
ascorbic acid in high concentration, formalin as
•Ammonium sulfate solubility test is used as a screening test for
•Myoglobin is soluble in 80% saturated solution of ammonium sulfate,
while hemoglobin is insoluble and is precipitated.
•A positive chemical test for blood done on supernatant indicates
1. Nitrite test:
Nitrites are not present in normal urine
Gram-negative bacteria (e.g. E.coli, Salmonella, Proteus,
Klebsiella, etc.) - reduce the nitrates to nitrites through
the action of bacterial enzyme nitrate reductase.
Nitrites are then detected in urine by reagent strip tests.
Some organisms like Staphylococci or Pseudomonas do
not reduce nitrate to nitrite - such infections nitrite test is
Urine must be retained in the bladder for minimum of 4
hours for conversion of nitrate to nitrite to occur;
therefore, fresh early morning specimen is preferred.
2. Leucocyte esterase test:
It detects esterase enzyme released in urine from
granules of leucocytes.
Thus the test is positive in pyuria.
If this test is positive, urine culture should be done.
The test is not sensitive to leucocytes < 5/HPF.
Also called as the “liquid biopsy of the urinary tract”.
Urine consists of various microscopic, insoluble, solid
elements in suspension - classified as organized or
◦ red blood cells, white blood cells, epithelial cells, casts, bacteria,
◦ are crystalline and amorphous material.
These elements are suspended in urine and on standing
they settle down and sediment at the bottom of the
container; therefore - known as urinary deposits or urinary
◦ The cellular elements are best preserved in acid, hypertonic saline.
◦ A mid-stream, freshly voided, first morning specimen is preferred.
◦ Examined within 2 hrs as casts and cells degenerate upon standing
at room temperature.
◦ 1 crystal of thymol or 1 drop of formalin is added to 10 ml of urine
◦ Well mixed sample of urine (12ml) is centrifuged in a centrifuge
tube for 5 minutes 1500 rpm and supernatant is poured off.
◦ The tube is tapped at the bottom to resuspend the sediment (0.5ml
◦ A drop of this is placed on a glass slide and covered with a cover slip
and is examined
Hematuria is the presence of abnormal number of red cells in urine
Presence of >3 cells/hpf is considered abnormal
Microscopy: smooth, non-nucleated, biconcave disks measuring
approximately 7 μm in diameter .
In concentrated (hypersthenuric) urine, the cells shrink due to
loss of water and may appear crenated or irregularly shaped
In dilute (hyposthenuria) urine, the cells absorb water, swell,
and lyse rapidly, releasing their hemoglobin and leaving only
the cell membrane called ghost cells.
If the specimen is not fresh when it is examined, the cells
appear as faint colorless circles or shadow cells because the
hemoglobin may dissolve out.
Dysmorphic - RBCs that
vary in size, have cellular
protrusions, or are
Clinical significance: >80%
strongly suggestive of renal
“G1 cell,”-doughnut shape
with one or more
membrane blebs, is more
specific than dysmorphic
cells for diagnosing
Dysmorphic RBCs (400).
Indicative of the extent of the damage to glomerular membrane or
injury to genitourinary tract.
(1) RENAL DISEASE
(2) LOWER URINARY TRACT DISEASE
(3) EXTRARENAL DISEASE
(4) TOXIC REACTIONS DUE TO DRUGS
(5) PHYSIOLOGIC CAUSES including exercise,
When increased numbers of erythrocytes are found in the urine in
conjunction with erythrocyte casts, bleeding may be assumed to be renal
Pyuria refers to the presence of abnormal numbers of
leukocytes(principally neutrophils- 10-12 μm in diameter) in urine.
Under high power, these cells appear as granular spheres about 12
μm in diameter with multilobated nuclei
Normal: < 5 WBC/hpf
WBCs. multilobed nuclei (400).
When cellular degeneration has begun, neutrophils become difficult to
distinguish from renal tubular epithelial cells. Dilute acetic acid may
enhance nuclear detail so that definition may still be possible
Supravital staining emphasize nuclear detail.
With crystal-violet safranin, neutrophilic nuclei- reddish purple and
cytoplasmic granules violet.
The peroxidase cytochemical reaction-also useful in distinguishing
neutrophils from tubular cells
WBCs with acetic acid nuclear enhancement
GLITTER CELLS: when exposed to hypotonic urine - absorb water
and swell. Brownian movement of the granules within these larger
cells produces a sparkling appearance. Because of the refractility of
the moving granules, neutrophils called as glitter cells.
Stain light blue with Sternheimer-Malbin stain, as opposed to voilet
of other neutrophils, will show loss of nuclear segmentation
◦ Clinical significance: Inflammation or Infection of urinary tract
Found in a variety of other urinary tract diseases including
-systemic lupus erythematosus (SLE), and
-acute or chronic localized inflammatory processes.
Physiological: transiently increased during fevers and following
Finding >1% among the leukocyte population is significant
A cytocentrifuge preparation with Wright’s, Diff-Quik, or
Papanicolaou stain is commonly used
Preferred - Hansel(methylene blue and eosin-Y in methanol)
Characterstic of acute interstitial nephritis due to drug reaction
Hansel-stained eosinophils (400).
◦ Lymphocytes, monocytes, plasma cells and histiocytes
◦ When constitute 30% or more of a differential count->
◦ Lymphocyturia - Causes: Chronic infection
An early marker of acute cellular rejection of renal allograft
In particular, the sequential determination of urinary CD3 positive
pan T cells after the first week following kidney transplantation may
contribute to the diagnosis of acute allograft rejection earlier than
Represent normal sloughing of old cells, unless present in
large numbers or in abnormal forms.
3 types: squamous cells, transitional(urothelial), and
renal tubular cells.
and RTE cells (400x)
Most frequent epithelial cells seen in normal urine and the least
largest cells found in the urine sediment.
Origin: the linings of the vagina and
distal one third of the urethra
Microscopy: large flattened cells abundant, irregular cytoplasm & a
small round prominent nucleus about the size of an RBC. The cell
edge is often folded; occasionally the cell rolled into a cylinder
• Line the urinary tract from the renal pelvis to the lower third of the
Microscopy: Smaller than squamous cells size ranging from 40–200
μm and appear in several forms, including spherical, polyhedral and
Frequently present in the sediment owing to their high turnover
Round or pear shaped, with a round centrally located nucleus with
occasional binucleate forms .
When stained, have dark blue nuclei with variable amounts of pale
Another helpful clue for identification is a characteristic ‘endo–ecto
Presence of large clumps or sheets of transitional cells in the
absence of instrumentation (i.e. catheterization) is considered
Vary in size and shape depending on the area of the renal tubules
from which they originate.
Most significant types of epithelial cells found in urine because
increased number indicates tubular damage
Cells from PCT : are larger then other RTE cells, rectangular shape.
Resemble casts hence the presence of nucleus has to be appreciated
Cells from DCT : are round to oval, with eccentric nucleus
Collecting duct cells: cuboidal, with the eccentrically placed
nucleus, appear in groups
Presence of >2 RTE cells/hpf indicates tubular injury
Small numbers of tubular cells may be seen in normal urine,
reflecting the normal sloughing of aging cells. They may be present
in somewhat larger numbers in the urine of normal newborns
PCT & DCT renal epithelial cells
acute tubular necrosis and
with certain drug or heavy metal toxicities.
collecting duct epithelial cells
• renal transplant rejection,
• acute tubular necrosis (diuretic phase)
• Other ischemic injuries to the kidney
• malignant nephrosclerosis
• acute glomerulonephritis accompanied by tubular damage
• Salicylate intoxication.
Three or more renal cells of collecting duct origin constitute a renal
Clinical significance: indicative of ischemic necrosis and are
usually found accompanying varying degrees of renal tubular injury
with basement membrane disruption and pathologic casts.
Proper identification is essential, to avoid a false-positive diagnosis
of low-grade transitional cell carcinoma.
RTE cells that have absorbed lipoproteins with cholesterol and
triglycerides leaked from nephrotic glomeruli, appear highly
Appears in the urine as free fatty droplets, or within histiocytes as
Positive identification of lipid is required before lipiduria is
When free or incorporated droplets contain large amounts of
cholesterol, they exhibit Maltese cross formation under polarized
When they contain large quantities of triglycerides, fat stains (Oil
Red O or Sudan III) are required for positive lipid identification.
The presence these lipid forms + marked proteinuria is characteristic
of the nephrotic syndrome
Also seen with
1. severe tubular necrosis
2. Diabetes mellitus
3. Trauma cases that cause release of bone marrow fat from the long bones.
Bubble cells: In cases of acute tubular necrosis, RTE cells
containing large, nonlipid-filled vacuoles may be seen along with
normal renal tubular cells and oval fat bodies.
1. With Hburia or myoglobinuria, heme pigment absorbed into the cells
and converted to hemosiderin. The iron-laden cells are found in the
urine sediment. The cytoplasmic granules appear yellow-brown and
stain for iron with Prussian blue.
2. Melanin granules -rare cases of melanuria. Pigmented tumor cells
are also found in cases of melanoma metastasis to the bladder.
3. Bilirubin pigment colors all of the elements of the sediment,
including renal tubular epithelial cells and casts.
Formed within the lumens of the DCTs and CTs
Composition: Tamm-Horsfall protein, albumin and
Casts may be -
1. Short and stubby, or
2. Long and convoluted- appears when diuresis occurs after
Typically have parallel sides and blunt ends, but with age they
may begin to disintegrate and show thinning and irregularities.
Clinical significance –
Increased numbers of casts usually indicate that kidney disease
is widespread, and that many nephrons are involved.
◦ Also be seen in healthy persons after strenuous exercise accompanied by
Casts are the only elements in the urinary sediment
that are specifically of renal origin.
Casts may be classified according to their matrix, inclusions,
pigments, and cells present
Most frequently seen cast
Consists almost entirely of Tamm-Horsfall protein
The presence of 0-2/lpf is considered normal
Microscopy: colorless in unstained sediments and have a refractive
index similar to that of urine;
Sternheimer-Malbin stain produces a pink color in hyaline casts
chronic renal disease, and
transiently with exercise, heat exposure,
dehydration, fever, congestive heart failure,
and diuretic therapy
Increased visualization can be obtained by phase microscopy
•The morphology is varied, consisting of normal parallel sides and
rounded ends, cylindroid forms, and wrinkled or convoluted shapes
that indicate aging of the cast matrix
Representative of extreme urine stasis, indicating chronic renal failure.
Differ from hyaline casts in that they are easily visualized because of
their high refractive index.
Microscopy: homogeneously smooth in appearance with sharp margins,
blunted ends, cracks or convolutions frequently seen along the lateral
margins, indicating a measure of brittleness often appear fragmented
with jagged ends and have notches in their sides
With supravital stains, waxy casts stain a homogenous, dark pink
Commonly associated with tubular inflammation and degeneration.
Most frequently in patients with chronic renal failure & during
acute and chronic renal allograft rejection.
Because time is required for granules to undergo lysis, waxy casts
imply localized nephron obstruction and oliguria.
When waxy casts are unusually broad, they are known as renal
failure casts, imply advanced tubular atrophy and/or dilation, in
turn reflecting end-stage renal disease and extreme stasis of urine
Indicates bleeding from an area within the genitourinary tract
Microscopy: easily detected under low power by their orange-red
color, fragile, have a more irregular shape as the result of tightly
packed cells adhering to the protein matrix
Prerequisite for identification is that red blood cell outlines should
be sharply defined in at least part of the cast
Better visualized with
supravital staining- casts are colorless or lavender in a pink matrix.
With prolonged stasis, red cell casts may degenerate and
appear in the urine as reddish brown, coarsely granular
hemoglobin (blood) casts.
Granular, dirty, brown casts representing hemoglobin
degradation products such as methemoglobin may also be
Subacute bacterial endocarditis
Rarely, tubulointerstitial disease may allow transtubular entry of
erythrocytes with subsequent incorporation into a cast. This may
occur in severe pyelonephritis.
Additionally, erythrocyte and leukocyte -> renal relapse in patients
Signifies infection or inflammation within the nephron
Microscopy: appear granular, and, unless disintegration has
occurred, multilobed nuclei will be present
Reflect tubulointerstitial disease with neutrophilic exudates and
The most common disease of this category is pyelonephritis-
primary marker for distinguishing pyelonephritis (upper UTI) from
Also seen in interstitial nephritis, lupus nephritis, and even the
Also present in nonbacterial inflammations such as acute interstitial
nephritis and may accompany RBC casts in glomerulonephritis.
Presence of advanced tubular destruction, producing urinary
stasis along with disruption of the tubular linings.
1. Acute tubular necrosis
2. Viral disease (e.g., cytomegalovirus disease)
3. Exposure to a variety of chemicals & drugs.
4. Heavy metal poisoning and ethylene glycol
5. Salicylate intoxication
6. Reliable criteria for detecting acute allograft rejection after the third
7. Also accompany WBC casts in cases of pyelonephritis
Owing to the formation of casts in the DCT, the cells visible on the
cast matrix are the smaller, round, and oval cells
Difficult to distinguish from leukocyte casts- The most reliable
distinguishing characteristic of renal tubular cells is their singular
Bilirubin-stained RTE cells are seen in cases of hepatitis, - hepatorenal failure
Include leukocyte/renal, erythrocyte/leukocyte, and eosinophil/renal
Frequently encountered include RBC and WBC casts
Glomerulonephritis- predominant RBC casts
Pyelonephritis- predominant casts WBC
May be of pathologic or non-pathologic significance.
May originate from plasma protein aggregates that pass into the
tubules from damaged glomeruli, as well as from cellular remnants
of leukocytes, erythrocytes, or damaged renal tubular cells.
◦ Fine salt precipitates and lysosomes
◦ Protein aggregates - fibrinogen, immune complexes, and globulins.
1. Glomerular and tubular diseases
2. Tubulointerstitial disease and
3. Renal allograft rejection.
5. viral infections
6. Chronic lead poisoning
7. Renal papillary necrosis- with hematuria
8. Hyperparathyroidism- fine granules represent calcium phosphate
9. Periods of extreme stress or strenuous exercise
Seen in conjunction with oval fat bodies and free fat droplets in disorders
Microscopy: highly refractile under bright-field microscopy.
Clinical significance: commonly seen when heavy proteinuria is present and
are a feature of nephrotic syndrome
Casts containing urates, calcium oxalate, and sulfonamides
(sulfamethoxazole) occasionally seen.
A matrix is visible in a true crystal cast, and the crystals may polarize.
These casts indicate deposition of crystals in the tubule or collecting
Hematuria, possibly related to tubular damage, regularly
accompanies crystal casts.
These casts should be carefully distinguished from clumps of crystals
forming at room or refrigerator temperatures.
Hemoglobin (Blood) Casts: typically appear yellow to red,
although sometimes the color is pale .
◦Most often seen with erythrocyte casts and glomerular disease.
◦Less commonly, with tubular bleeding and rarely with hemoglobinuria.
Hemosiderin Casts. Hemosiderin granules in casts derived from
pigment laden renal tubular cells.
Myoglobin Casts: red-brown in color & occur with myoglobinuria
following acute muscle damage.
Often referred to as renal failure casts
Diameter 2-6 times that of normal casts.
-indicates destruction (widening) of the tubular walls
-indicate tubular dilation and/or stasis in the distal collecting duct.
Most commonly broad casts- granular and waxy & have poor
Bile-stained broad, waxy casts are seen as the result of the tubular
necrosis caused by -viral hepatitis
Containing bacilli both within and bound to the protein matrix -
seen in pyelonephritis
Confirmation is best made by performing a gram stain on the dried
or cytocentrifuged sediment.
“gold standard” -quantifying bacterial counts is culture
1. nephrotic syndrome
2. toxic tubular necrosis
3. diabetes mellitus, and
4. crush injuries.
Appear as true geometrically formed structures or as amorphous material
Clinical significance: represent disorders as
1. Liver disease
2. Inborn errors of metabolism
3. Renal damage caused by crystallization of iatrogenic compounds
within the tubules.
Formed by the precipitation of urine solutes, including inorganic salts,
organic compounds, and medications (iatrogenic compounds) when
alterations in multiple factors affect their solubilities.
1. Changes in temperature
2. Solute concentration, Increased solute concentration is typically
responsible for crystal formation
3. pH-determines the type of chemicals precipitated which affect solubility.
First consideration is the urine pH.
All abnormal crystals are found in acidic urine.
The geometric shape of a crystal determines its birefringence and,
therefore, its ability to polarize light
Precipitate upon standing in concentrated urine of a slightly acid pH
Microscopy : yellow brown granules. may occur in clumps, and
adhere to fibers and mucous threads
When large quantities are present, the urine sediment may appear
pink-orange to reddish brown on macroscopic examination this
appearance has been referred to as brick dust due to the
accumulation of the pigment, uroerythrin, on the surface of
Seen in conjunction with amorphous urates
Acid urates appear as larger granules and may have spicules similar
to the ammonium biurate crystals seen in alkaline urine
Sodium urate crystals are needle-shaped and are seen in synovial
fluid during episodes of gout, but do appear in the urine.
Occur at low pH (5–5.5)
Microscopy : seen in a variety of shapes, including rhombic or four-
sided flat plates, prisms, oval forms with pointed ends (lemon-
shaped), wedges, rosettes, and irregular plates.
Appear yellow-brown, may be colorless and hexagonal, resembling
Highly birefringent under polarized light, which aids in
distinguishing them from cystine crystals
1. Associated with increased levels of purines and nucleic acids in
patients with leukemia who are receiving chemotherapy
2. In patients with Lesch-Nyhan syndrome &
3. (sometimes) in patients with gout.
The most common form is the dihydrate recognized as a colorless,
octahedral envelope or as two pyramids joined at their bases.
Dihydrates may appear at pH 6 or in neutral urine
Less frequently seen is the monohydrate form, oval or
They are soluble in dilute hydrochloric acid.
Ingestion of certain foods like tomatoes, spinach, cabbage,
asparagus, and rhubarb causes increase in their numbers
1. The finding of clumps in fresh urine may be related to the
formation of renal calculi
2. Large numbers may reflect severe chronic renal disease or
ethylene glycol or methoxyflurane toxicity.
3. Their increased number in fresh urine (oxaluria) may also
suggest oxalate stones.
1. Amorphous phosphate
2. Triple phosphate and
3. Calcium Carbonate
4. Ammonium Biurate.
Phosphates represent the majority of the crystals seen in alkaline
urine cause white precipitate that does not dissolve on warming.
Microscopy: granular in appearance, similar to amorphous urates
unlike the former, they tend to be colorless and will produce a fine
or lacy white precipitate macroscopically
Triple phosphate (ammonium magnesium phosphate)
Microscopy: they are colorless, three to six-sided prisms with oblique ends
referred to as coffin lids
Have little if any clinical significance.
They are often seen in infected urine of alkaline pH
Uncommon crystals are small and colorless, with dumbbell or
spherical shapes form pairs, fours, or clumps.
Distinguished from other crystals/amorphous material by their
production of carbon dioxide in the presence of acetic acid.
They are also birefringent, which differentiates them from bacteria
Exhibit the characteristic yellow-brown color
Soluble in acetic acid at 60 degree C.
Microscopy: described as “thorny apples” because of their
appearance as spicule-covered spheres
Found in acidic urine or rarely in neutral urine.
1. Cystine Crystals
4. Sulfonamide(sulfadiazine) Crystals
5. Ampicillin Crystals
6. Radiographic Dye Crystals
7. Cholesterol Crystals
8. Crystals Associated With Liver Disorders
Found in the urine of persons who inherit a metabolic disorder that
prevents reabsorption of cysteine by the renal tubules (cystinuria).
Microscopy: Cysteine crystals appear as colorless, refractile,
hexagonal plates and may be thick or thin
1. Among the most important crystals identified in urine sediment.
2. Occur in patients with cystinuria and may be associated with
In acidic urine, tyrosine forms fine silky needles that may be
arranged in sheaves or clumps, especially after refrigeration.
These may be colorless or yellow, appearing black as the
microscope is focused .
They are soluble in alkali (ammonia and potassium hydroxide) and
dil HCL; they are not soluble in alcohol or ether.
2. Occasionally seen in the urine of patients with severe liver disease
Microscopy: yellow-brown oily-appearing spheres that demonstrate
concentric circles and radial striations
Usually accompanied by tyrosine crystals in severe liver diseases.
Leucine may be precipitated with tyrosine crystals if alcohol is
added to the urine
Microscopy: seen as yellow-brown sheaves of wheat with central
bindings, striated sheaves with eccentric bindings, rosettes,
arrowheads, petals, needles, and round forms with radial striations.
Clinical significance: seen in the urine of patients on sulfonamide
therapy who were inadequately hydrated. This could result in renal
tubular damage if crystal formation occurred within the nephron.
Encountered in massive doses of penicillin compound without
Microscopy: appear as long, fine colorless needles that tend to form
bundles following refrigeration
Microscopy: rectangular plate with a notch in one or more corners
Cholesterol crystals are highly birefringent with polarized light
Clinical significance: associated with disorders producing lipiduria,
such as the nephrotic syndrome, and in conjunction with fatty casts
and oval fat bodies
Form after radiographic examinations using diatrizoate dyes.
May be found in urine of acid pH shortly after intravenous
radiographic studies (particularly if the patient has not been well
Microscopy: appearing as flat, clear, colorless, notched rhombic
plates, or longer, slender rectangles.
They are easily polarized, showing interference colors
The presence of radiographic crystals should correlate with a high
specific gravity (>1.040).
Bilirubin crystals: present in hepatic disorders producing large
amounts of bilirubin in the urine
Microscopy: appear as clumped needles or granules with the
characteristic yellow color of bilirubin
Clinical significance: In
disorders that produce renal
tubular damage, such as viral
hepatitis, bilirubin crystals may
be found incorporated into the
matrix of casts.
May be present in the form of cocci (spherical) or bacilli (rods).
Reported as few, moderate, or many /hpf
If bacteria are identified with Gram's stain in an centrifuged urine
specimen under an oil-immersion lens
suggests >100 000 organisms/mL are present (i.e. significant
Clinical significance: indicative of either lower or upper UTI.
To be considered significant for UTI, bacteria should be accompanied
Bacteria associated :
1. Enterobacteriaceae (referred to as gram- negative rods)
2. Cocci-shaped Staphylococcus & Enterococcus
3. Acid-fast bacilli may be seen, but because the urethral flora may contain
nonpathogenic acid-fast organisms, the presence of Tuberculosis in urine
must be substantiated by culture and/or polymerase chain reaction (PCR)
Microscopy: appear in the urine as small, refractile oval structures
In severe infections, they may appear as branched, mycelial forms
Clinical significance: primarily Candida albicans,
◦ urine of diabetic
◦ immunocompromised patients and
◦ women with vaginal moniliasis.
vaginal contamination should be ruled out, which is likely when the
background contains numerous squamous cells and bacteria and few
1. Trichomonas vaginalis- Most frequent parasite
encountered in urine.
◦ Pearshaped flagellate with an undulating membrane,
rapid darting movement The nucleus is small and
oval, & the cytoplasm contains fine red granules
◦ Clinical significance: sexually transmitted pathogen
associated primarily with vaginal inflammation, but
it can cause urethritis and even prostatitis
2. Microfilaria: seen in chyluria of filariasis as
long, filamentous structure with an outer sheath
3. The ova of the bladder parasite Schistosoma haematobium will
appear in the urine accompanied by red cells.
4. Fecal or vaginal contamination of a urine specimen also result in
the presence of ova from intestinal parasites in the urine
sediment. The most common contaminant is ova from the
pinworm Enterobius vermicularis
Enterobius vermicularis Schistosoma haematobium
5. Amoebae are rarely seen in the urine
◦ These may reach the bladder from lymphatics or more likely from
fecal contamination of the urethra
◦ Usually accompanied by erythrocytes and leukocytes.
Entamoeba histolyitca cyst
Identified in the urine sediment by their oval, slightly tapered heads and
long, flagella like tails
Urine is toxic to spermatozoa; therefore, they rarely exhibit the motility
Clinical significance: in cases of male infertility or retrograde ejaculation
in which sperm is expelled into the bladder instead of the urethra.
Protein material produced by the glands and epithelial cells of the
lower genitourinary tract and RTE cells.
Tamm-Horsfall protein- glycoprotein excreted by the RTE cells of
the distal convoluted tubules and upper collecting duct is a major
constituent of mucus
Microscopy: thread-like structures with a low refractive index
no clinical significance
Mucus in urine with
Found in specimens collected under improper conditions or in dirty
The most frequently encountered artifacts include starch, oil
droplets, air bubbles, pollen grains, fibers, and fecal contamination.
often very highly refractile or occur in a different microscopic plane
than the true sediment constituents.
1. Partially digested muscle fibers or vegetable cells may be found
when fecal contamination occurs
2. Pollen grains contaminate specimens seasonally, appear as spheres
with a cell wall and occasional concentric circles
3. Starch granule contamination: occur when corn starch powder is
used in powdered gloves
Microscopy: highly refractile spheres, usually with a dimpled center
4. Oil droplets may result from contamination by immersion oil or
lotions and creams
5. Air bubbles occur when the specimen is placed under a cover slip.
6. Hair and fibers from clothing and diapers may initially be
mistaken for casts, though they are usually much longer and more
◦ Unlike casts, these fibers polarize brightly.
7. Fecal artifacts may appear as plant and meat
fibers or as brown amorphous material in a
variety of sizes and shapes
Casts are reported as the average number per low-power field (lpf)
following examination of 10 fields
RBCs and WBCs, as the average number per 10 high-power fields
Epithelial cells, crystals, and other elements are frequently
reported in semi quantitative terms such as, rare, few, moderate, and
many, or as 1, 2, 3,and 4, following laboratory format as to lpf or
McPherson RA, Ben-Ezra J. Basic examination of urine. In:
McPherson RA, Pincus MR. Henry’s Clinical Diagnosis &
management by laboratory methods. 22nd ed : Saunders
Elsevier ; 2011. p. 463-74.
Strasinger SK, Lorenzo MSD. Urine analysis and body fluids, 5th
ed, Philadelphia: Davis company;2008. p.82-119
Essentials of Clinical Pathology 2010 by Shirish M Kawthalkar
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