Transcript Collecting Processing and Testing Urine Specimens

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Contains few epithelial cells, occasional
RBC’s, few crystals.
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95% water
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5% waste products
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Other dissolved chemicals
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Urea
Uric acid
Ammonia
Calcium
Creatinine
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Sodium
Chloride
Potassium
Sulfates
Phosphates
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Hydrogen ions
Urochrome
Urobilinogen
A few RBCs
A few WBCs
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Random urine specimen
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Most common
Obtained any time
during the day
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Clean-catch midstream
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Used for culturing urine
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External genitalia must
be cleansed
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Discard small amount of
urine prior to collecting
specimen
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Can also obtain by
catheterization
First morning specimen
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Contains greater
concentration of
substances
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Timed urine specimen
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24-hour specimen
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Discard first specimen
Collect all urine for specified time
Refrigerate
Collected as a timed specimen
Both are used for qualitative and
quantitative analysis
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Urinary catheter – a
plastic tube inserted to
provide urinary
drainage
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Catheterization –
procedure by which the
catheter is inserted
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Chemical, physical, and microscopic
changes occur if urine is left at room
temperature for more than 1 hour
Preservation
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Refrigeration
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Prevents growth for 24 hours
Return to room temperature before testing
Chemical preservatives
Specimens
only
Normal= aromatic due to the volatile fatty acids
 Ammonical – bacterial action
 Fruity- ketonuria
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The normal pale yellow color of urine is due to
the presence of the pigment urochrome
 Urine color varies most commonly because of
concentration, but many foods, medications,
metabolic products, and infection may produce
abnormal urine color.
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Cloudy urine is most commonly due to phosphaturia
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The large numbers of white blood cells cause the urine to become
turbid.
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Pyuria is readily distinguished from phosphaturia either by
smelling the urine (infected urine has a characteristic pungent odor)
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Rare causes of cloudy urine include chyluria (in which there is an
abnormal communication between the lymphatic system and the
urinary tract resulting in lymph fluid being mixed with urine),
lipiduria, hyperoxaluria, and hyperuricosuria.
Common Causes of Abnormal Urine Color
Colorless
Cloudy/milky
Red
Orange
Very dilute urine
Overhydration
Phosphaturia
Pyuria
Chyluria
Hematuria
Hemoglobinuria/myoglobinuria
Anthrocyanin in beets and blackberries
Chronic lead and mercury poisoning
Phenolphthalein (in bowel evacuants)
Phenothiazines (e.g., Compazine)
Rifampin
Dehydration
Phenazopyridine (Pyridium)
Sulfasalazine (Azulfidine)
Common Causes of Abnormal Urine Color
Yellow
Normal
Phenacetin
Riboflavin
Green-blue
Biliverdin
Indicanuria (tryptophan indole metabolites)
Amitriptyline (Elavil)
Indigo carmine
Methylene blue
Phenois (e.g., IV cimetidine [Tagamet],
IV promethazine [Phenergan])
Resorcinol
Triamterene (Dyrenium)
Brown
Urobilinogen
Porphyria
Aloe, fava beans, and rhubarb
Chloroquine and primaquine
Furazolidone (Furoxone)
Metronidazole (Flagyl)
Nitrofurantoin (Furadantin)
Brown-black
Alcaptonuria (homogentisic acid)
Hemorrhage
Melanin
Tyrosinosis (hydroxyphenylpyruvic acid)
Cascara, senna (laxatives)
Methocarbamol (Robaxin)
Methyldopa (Aldomet)
Sorbitol
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Ketone bodies
Normally none in
urine
 Presence
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Patient on a lowcarbohydrate diet
Starvation
Excessive vomiting
Diabetes mellitus
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pH
Normal 5.0 to 8.0
 Alkaline
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UTI
Metabolic /
respiratory alkalosis
Acidic
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Phenylketonuria
Acidosis
Reaction reflects ability of kidney to maintain
normal hydrogen ion concentration in plasma
& ECF
 Normal= 4.6-8
 Tested by- 1.litmus paper
2. pH paper
3. dipsticks
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Urinary pH is measured with a dipstick test strip(
methyl red and bromothymol blue), which yield
clearly distinguishable colors over the pH range
from 5 to 9.
Urinary pH may vary from 4.5 to 8;
The average pH varies between 5.5 and 6.5.
A urinary pH between 4.5 and 5.5 is considered
acidic, whereas a pH between 6.5 and 8 is
considered alkaline.
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In patients with a presumed UTI, an alkaline
urine with a pH greater than 7.5 suggests
infection with a urea-splitting organism, most
commonly Proteus.
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Urinary pH is usually acidic in patients with uric
acid and cystine lithiasis.
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Alkalinization of the urine is an important
feature of therapy in both of these conditions
Ketosis-diabetes, starvation, fever
 Systemic acidosis
 UTI- E.coli
 Acidification therapy
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Alkaline urine
Strict vegetarian
 Systemic alkalosis
 UTI- Proteus
 Alkalization therapy
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Leukocyte esterase activity indicates the presence
of white blood cells in the urine.
The presence of nitrites in the urine is strongly
suggestive of bacteriuria
The major cause of false-positive leukocyte
esterase tests is specimen contamination
Nitrites are not normally found in the urine, but
many species of gram-negative bacteria can
convert nitrates to nitrites
Causes of sterile pyuria
A recently (within last 2 weeks) treated urinary tract
infection (UTI) or inadequately treated UTI.
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UTI with 'fastidious' organism (an organism that
grows only in specially fortified artificial culture
media under specific culture conditions), eg
Neisseria gonorrhoeae.
Renal tract tuberculosis, chlamydial urethritis
False negative culture due to contamination with
antiseptic.
False negative culture due to contamination with
antiseptic.
Contamination of the sample with vaginal leukocytes.
Interstitial nephritis: sarcoidosis (lymphocytes not
neutrophils)
Urinary tract stones
Renal papillary necrosis: diabetes,
sickle cell disease, analgesic
nephropathy.
Urinary tract neoplasm, including
renal cancer and bladder cancer.
Polycystic kidneys. Interstitial
cystitisProstatitis.
Other reported associations
include appendicitis, systemic
lupus erythematosus and
Kawasaki disease.
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The most common yeast cells found in urine are
Candida albicans
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Yeasts are most commonly seen in the urine of
patients with diabetes mellitus or as
contaminants in women with vaginal
candidiasis.
Protocol for determining the need for urine sediment microscopy in an
asymptomatic population
Crystals in acidic urine
 Uric acid
 Calcium oxalate
 Cystine
 Leucine
Crystals in alkaline urine
 Ammonium magnesium
phosphates(triple
phosphate crystals)
 Calcium carbonate
Urinary crystals
Acute Renal Failure
Crystals – Pretty and important.
Uric acid crystals:
Seen in any setting of
elevated uric acid and an
acidic urine.
Seen with tumor lysis
syndrome.
UpToDate Images.
Calcium oxalate crystals:
Monohydrate – dumbell
shaped, may be needle-like.
Dihydrate – envelope shaped.
Form independent of urine pH.
Seen acutely in ethylene glycol
ingestion.
Casts
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Urinary casts are cylindrical aggregations of
particles that form in the distal nephron,
dislodge, and pass into the urine. In urinalysis
they indicate kidney disease. They form via
precipitation of Tamm-Horsfall mucoprotein
which is secreted by renal tubule cells.
Casts
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Tamm-Horsfall mucoprotein is the basic matrix of all
renal casts; it originates from tubular epithelial cells and
is always present in the urine
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When the casts contain only mucoproteins, they are
called hyaline casts and may not have any pathologic
significance.
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Red blood cell casts contain entrapped erythrocytes and
are diagnostic of glomerular bleeding, most likely
secondary to glomerulonephritis
Casts
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White blood cell casts are observed in acute
glomerulonephritis, acute pyelonephritis, and acute
tubulointerstitial nephritis
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Granular and waxy casts result from further
degeneration of cellular elements.
Fatty casts are seen in nephrotic syndrome, lipiduria,
and hypothyroidism.
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Acellular casts
Hyaline casts
Granular casts
Waxy casts
Fatty casts
Pigment casts
Crystal casts
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Cellular casts
Red cell casts
White cell casts
Epithelial cell cast
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The most common type of cast, hyaline casts
are solidified Tamm-Horsfall mucoprotein
secreted from the tubular epithelial cells
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Seen in fever, strenuous exercise, damage to
the glomerular capillary
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waxy casts suggest severe, longstanding
kidney disease such as renal failure(end stage
renal disease).
Granular casts
Granular casts can result either from the
breakdown of cellular casts or the inclusion of
aggregates of plasma proteins (e.g., albumin)
or immunoglobulin light chains
 indicative of chronic renal disease
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Introduction to casts…
Hyaline Casts:
Better seen with low
light.
Non-specific.
Composed of TammHorsfall mucoprotein.
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waxy casts suggest severe, longstanding
kidney disease such as renal failure(end stage
renal disease).
Granular Casts:
Represent degenerating
cellular casts or aggregated
protein.
Nonspecific.
UpToDate Images.
Waxy Casts:
Smooth appearance.
Blunt ends.
May have a “crack”.
Felt to be last stage of
degenerating cast –
representative of chronic
disease.
Formed by the breakdown of lipid-rich epithelial
cells, these are hyaline casts with fat globule
inclusions
They can be present in various disorders, including
 nephrotic syndrome,
 diabetic or lupus nephropathy,
 Acute tubular necrosis
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Formed by the adhesion of metabolic breakdown
products or drug pigments
 Pigments include those produced endogenously,
such as
 hemoglobin in hemolytic anemia,
 myoglobin in rhabdomyolysis, and
 bilirubin in liver disease.
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Though crystallized urinary solutes, such as
oxalates, urates, or sulfonamides, may become
enmeshed within a hyaline cast during its
formation.
 The clinical significance of this occurrence is not
felt to be great.
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The presence of red blood cells within the cast is
always pathologic, and is strongly indicative of
glomerular damage.
 They are usually associated with nephritic
syndromes.
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Indicative of inflammation or infection,
 pyelonephritis
 acute allergic interstitial nephritis,
 nephrotic syndrome, or
 post-streptococcal acute glomerulonephritis
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White Blood Cell Casts:
Raises concern for
interstitial nephritis.
Can be seen in other
inflammatory disorders.
Also seen in
pyelonephritis.
UpToDate Images.