Download (1) Urine samples collected randomly during the day are - E

UNIT-II
Urine analysis – collection – physical, chemical and microscopic examination of
urine – CSF , Parasite analysis
EXPLAIN ABOUT URINE ANALYSIS: (SECTION C)
Physical Examination of Urine: (Section B)
All routine urinalysis should begin with a physical examination of the urine sample. This examination
includes assessment of volume, odor, and appearance (color and turbidity).
Volume
Urinary volume is dependent upon fluid intake; amount of solutes to be excreted, primarily sodium and
urea; loss of body fluids by normal processes, such as perspiration and respiration, and abnormal
processes, such as diarrhea; and cardiovascular and renal function. Although the volume of a random
specimen is clinically insignificant, the volume of specimen received should be recorded for purposes
of documentation and standardization.
Urine volumes can be measured two ways: volumetrically and gravimetrically. That is, the volume is
measured with a volumetric cylinder, or the volume is estimated by weighing the urine sample in a
tared container and assuming that 1g = 1mL of urine.
Odor
Non-pathological, fresh urine has an inoffensive odor. One usually determines the odor of the urine
sample by placing ones nose near the orifice of the sample container , moving the air from the container
to your nose by gently wafting with your hand, and gently breathing the fumes.
Appearance (color and turbidity)
Color—The color of urine is related, to a large degree, by its degree of concentration. The color of nonpathological urine varies widely from colorless to deep yellow; the more concentrated the urine, the
deeper the color. The color of urine is usually described after visual inspection with common color
terms. Very often color charts will be available to report the colors in a consistent fashion.
A good clinical history can resolve possible causes of an unusual urine color.
Turbidity—Normally freshly voided urine is clear. When urine is
allowed to stand, amorphous crystals, usually urates, may precipitate
and cause urine to be cloudy. The turbidity of urine should always be
recorded and microscopically explained.
Specific gravity—A hydrometer (urinometer) and a suitable
container may be used to determine specific gravity.
Many laboratories may also be equipped with refractometers that can relate density
of a solution to specific gravity. Refractometers work on the principle that light
passing from a transparent medium of one density to a medium of another density,
will change its velocity and therefore the direction in which the beam of light is
moving.
This change in direction, or the bending, of light is
called refraction. The refractivity of a solution is
Urinometer
dependent, in great part, on the total mass of solids
Refractometer
dissolved in that solution. The refractive index
scale can be calibrated to measure the specific gravity of most urine sample, that is up to 1.036 g/mL .
An indirect colorimetric method for estimating specific gravity is
available on reagent strips ("urine dipsticks"). This method uses a pad
that contains a complex, pre-treated electrolyte that undergoes a pH
change based on the ionic concentration of the urine. This change
results in a change of color of the pad. For the Multistix SG-10,
specific gravity is measured using an apparent pKachange in the
presence of an indicator (dyes) whose colors vary from deep bluegreen at low ionic strength to green and yellow-green at higher ionic
concentration. This estimate of specific gravity is rapid, simple, and
Urine dipsticks
requires no special equipment.
The falling drop method is a direct method of measuring specific gravity that is usually used with
automated instruments, such as the Clinitek Auto 2000 (Ames Division, Miles Laboratories, Inc.,
Elkhart , IN). The CliniTek2000 uses a specially designed column containing silicone oil. Specific
gravity is calculated from the time it takes for a drop of urine to fall between two optical gates.
Osmolality—Osmolality is usually measured by an osmometer, most frequently by a freezing point
osmometer. Osmolalityis a measure of the number of particles per unit mass, whereas the specific
gravity is a reflection of the density (mass per unit volume) of the suspended particles.
Clinical Significance—Primary kidney function includes the ability to produce, in the appropriate
circumstances, either a concentrated urine (osmolality>850 mOsm/kg) or a dilute urine (osmolality<100
mOsm/kg). A random urine whose osmolality>600 mOsm/kg is presumptive evidence of an ability to
concentrate urine. The urine osmolality thus is part of the mechanism of maintaining water balance. In
the presence of excess free water, the kidneys will produce a dilute urine, while in periods of water lack,
a concentrated urine is produced.
Loss of concentrating ability is often one of the earliest signs of kidney disease, clinically evidenced as
nocturia (needing to void at night) and polyuria (increased volume of [usually dilute] urine).
Laboratory Tests
The concentration of urine varies throughout 24 hour period, it depends on water intake of a person and
partly on his activities. A random urine specimen collected during the day time may be diluted and may
not be suitable for detection of certain su
Laboratory Tests
The various aspects considered for the routine urine examination are as follows:
Specimen
Collection of Urine Specimen
• Type of specimen: First voided midstream morning urine.
Note:
1) The concentration of urine varies throughout 24 hour period, it depends on water intake of a person
and partly on his activities. A random urine specimen collected during the day time may be diluted and
may not be suitable for detection of certain substances present in low concentration. Hence more
concentrated urine is preferred for testing, which can be obtained by collecting first voided morning
urine.
2) For urgent routine examination, however, to get general idea of expected pathological condition a
random urine specimen may be used.
• Container used for urine collection Clean and dry wide mouth glass or plastic bottles, with screw-cap tops. (capacity, about 250-300 ml)
Note: The bottles need not be sterile.
• Instructions given to the patient
1) The patient should be instructed to void directly into the container. During the collection the initial
portion of the urine stream is allowed to escape while the mid stream portion is collected.
2) Specimens from infants and young children can be collected in a disposable collection apparatus. It
consists of a plastic bag with an adhesive backing about the opening to fasten it to the child so that he
voids directly into the bag. Care must be taken to avoid fecal contamination.
Note: For qualitative tests, the morning urine is useful, however, quantitative jests are performed only
on urine specimen collected for 24 hrs.
• Preservation
All the specimen for routine urinalysis should be examined while fresh (within one hour of the
collection). When urine is kept for longer than one hour before analysis, to avoid deterioration of
chemical and cellular material and to prevent multiplication of bacteria, it should be stored at 2-8°C in a
refrigerator.
Note: The expected changes in the composition of urine stored at room temperature are as follows:
-
Lysis of red blood cells by hypotonic urine
-
Decomposition of casts.
-
Bacterial multiplication.
-
Decrease in glucose level, due to bacterial growth.
-
Formation of ammonia from urea by the action of bacteria (and the nature of urine changes to
alkaline).
The recommended preservatives are as follows:
Preservative
Concentration
Limitations
Tolune
2ml / 100ml urine
It floats on the surface of
urine, good for chemical
constituents. It is not
effective if bacteria are
already present in urine.
Formalin
3 drops / 100 ml urine
Good for sediments. May
precipitate proteins.
Thymol
One small crystal per 100
May interfere with the acid
ml of urine
precipitation test for
proteins.
Chloroform
5ml per 100 ml urine
Forms upper layer. It causes
changes in the
characteristics of the
cellular sediment.
Commercial preservative
1 tablet / 30ml urine
Concentration of
tablets. These release
formaldehyde is controlled,
formaldehyde
so that it may not interfere.
Additional Information
(1) Urine samples collected randomly during the day are sometimes so dilute due to increased fluid
consumption that they tend to give a false picture of patient’s health.
(2) However, for detection of glycosuria post—prandial urine (sample collected, 2 hrs. after lunch or
dinner) is the best.
CHEMICAL TESTING: (SECTION B)
Reagent-strip Testing
A plastic strip is used, which contains pads that have incorporated within them the reagents for
chemical reactions for the detection of a number of urine constituents. Urine is added to the pads for
reaction by dipping the plastic strip into the urine and then slowly withdrawing it. The subsequent
colorimetric reactions are timed to an endpoint; the extent of colors formation is directly related to the
level of the urine constituent. The colors can be read manually by comparison with color charts or with
the use of automated reflectance meters.
The following are four general rules to be followed when performing urine reagent strip testing.
1.
Test urine promptly; use properly timed test readings only.
2.
Beware of interfering substances.
3.
Understand the advantages and limitations of the test.
4.
Employ controls at least once per day, documenting the results.
Positive results from reagent-strip testing may require confirmation with chemical and microscopic
methods.
Manufacturers' information on sources of inhibitors and false-positive and false-negative results can be
identified from the package inserts of the test strips. For example, ascorbic acid in urine can interfere
with reagent-strip reactions for glucose, hemoglobin, bilirubin, and nitrite.
Manufacturers have been encouraged to minimize or eliminate this interference when possible because
ingestion of vitamin C supplements is so common. Some reagent test strips have an additional test
reaction that measures the levels of urinary ascorbic acid, and serve as a reminder of the possibility of
interference from this source.
Test Principles, Significance, and Normals
1.
pH
2.
Proteins
3.
Sugars
4.
Ketones
5.
Blood and myoglobin
6.
Bilirubin
7.
Urobilinogen
8.
Nitrities
9.
Leukocyte esterase
1. pH: (Section A)
Most urinalysis laboratories use multi-test reagent strips containing two pH indicators, methyl red and
bromthymol blue. These provide a range of sensitivity to pH from 5.0 to 9.0; the pH is reflected by a
color which can change from orange (acid) to green to blue (alkaline).
Fresh urine specimens can have pH values ranging from acidic to alkaline. Upon standing the
decomposition of urea into ammonia causes the urine to become more alkaline. Lower pH values are
observed in cases of diabetes and in patients with fever. Urine retention by some patients can result in
more alkaline urine. The standard method for pH measurements uses glass electrodes. Urinary pH
measured with indicator paper is more than accurate enough for clinical purposes, since small changes
in urinary pH are of little clinical significance. There is no confirmatory testing for urine pH.
Clinical significance—Common clinical causes of acidic and alkaline urine are listed in the following
table. The normal American diet is high in protein that results in acidic urine (pH 5.0 to 6.5). Alkaline
urines (pH 8.0 to 8.5) are more often associated with an unpreserved or old specimen, which turns
alkaline as the result of urease-producing ammonia bacteria, such as Proteus species. Patients with renal
tubular acidosis, a clinical syndrome characterized by an inability to excrete an acidic urine, may
produce urine with a much higher pH than would be expected on the basis of the acidosis.
Normal—The urinary pH range is usually 4.7 to 7.8. Extremely acidic or alkaline urine usually
indicates a poorly collected specimen.
2. Proteins: (Section A)
Reagent-strip test for protein is a semi-quantitative screening procedure for proteinuria. Reagent strips
contain a pH sensitive dye; tetrabromphenol blue and 31, 35, 51, 55 tetrachlorophenol-3,4,5,6tetrabromosulfophthalein. The presence of protein on the strip changes the pH environment of the dye
embedded in the pad, resulting in a change in color.
pH 3
Tetrabromphenol
Positive results
blue
(green-blue)
Protein
pH 3
Tetrabromphenol
Negative results
blue
(yellow)
No protein
Strip tests are more sensitive for albumin and can detect other proteins at higher concentrations. Thus,
because there is a risk for false-negative results, it is recommended that the laboratory consider
simultaneously performing both a reagent-strip test and an acid precipitation test for the detection of all
types of proteinuria. A faintly positive result should be confirmed with a more specific test such as the
trichloroacetic acid or the sulfosalicylic acid tests. A grossly positive SSA or TCA turbidity test result
may indicate the presence of drugs or Bence Jones proteins.
False positive results maybe caused by alkaline or buffered urine as well as by quarternary ammonium
compounds found in detergents.
Clinical significance—Most of the urine protein is albumin, which has crossed the glomerular
membrane. Smaller-molecular-weight proteins such as globulins may also be present in urine. Once
filtered at the glomerulus, proteins are almost completely reabsorbed in the proximal tubule.
Proteinuria, therefore, can be the result of either increased filtration at the glomerulus or decreased
tubular reabsorption. Glomerular proteinuria is associated with the presence of larger molecular weight
proteins and larger protein losses, usually > 2 g/day. The nephrotic syndrome is associated with very
large losses of protein, usually >2-3 g/day. Tubular proteinuria is associated with smaller amounts (1-3
g/day) of lower molecular weight protein molecules. Small losses of protein in urine can be seen with
vigorous exercise and pregnancy.
Measurement of urinary pH is also useful for managing patients with renal stones or crystals. Uric acid
stones form in acidic urine and are more soluble in alkaline urines. However, alkaline urine will
precipitate calcium or calcium phosphate crystals, while an acidic urine will tend to dissolve them.
Inducing an alkaline urine during sulfonamide and streptomycin therapy is done to prevent precipitation
of these drugs in the kidneys and to prevent the formation of uric acid, cystine, and oxalate stones.
Alkaline urines are also desirable during treatment of transfusion reactions and salicylate intoxication.
An acidic pH is used to combat bacteriuria in patients with cystitis and to prevent formation of alkaline
stones. Technologists should be aware that alkaline urine interferes with the determination of proteins
by the reagent strip technology and may alter the urine sediment examination.
Normal—A healthy person will excrete up to approximately 100 mg/day, a very small fraction of the
plasma protein that is filtered at the glomerulus.
3. Sugars : (Section A)
Enzymatic testing—The reagent-strip tests are highly specific for glucose. They detect the oxidation of
glucose to gluconic acid:
Glucose
oxidase
Glucose +
Gluconic acid +
Oxygen in room
Hydrogen peroxide
air
Peroxidase
Hydrogen peroxide
Oxidized chromogen
+ Chromogen
(blue) + H2O
Tetramethylbenzidine and o-toluidine have been used as the chromogen for the indicator reaction.
Copper reduction (Clinitest, Benedict's test)—The Clinitest tablet (Ames Division, Miles Laboratories,
Inc., Elkhart, IN) usually serves as a confirmatory test for sugar. Using the principle of the reduction of
cupric salts by reducing sugars; including glucose, galactose, lactose, and pentoses; the copper
reduction test measures total reducing substances in urine.
Heat
Cupric ions + Glucose
Cuprous
(or other reducing substances)
oxide
Alkali
(red)
+
Cuprous
hydroxide
(yellow)
Clinical significance—Glucose is the predominant sugar in urine. It is not detectable by reagent strips in
the urine of healthy individuals. Temporary elevation of glucose excretion measurable by test strips can
occur after treatment with some drugs, cases of shock and during pregnancy. Repeated positive testing
is almost always diagnostic for diabetes.
Reagent strips will detect glucose at a concentration of 400 to 750 mg/L (2.2 to 3.85 mmol/L), while the
Clinitest will detect reducing substances at a concentration of 2000 mg/L (~ 11 mmol/L) or greater. The
copper reduction method will also detect ascorbic acid and certain drugs, such as, nalidixic acid
[NegGram]), used to treat urinary tract infections; probenecid, used to treat gout; and cephalosporin, an
antibiotic.
Because Clinitest is both less specific and less sensitive than the reagent strip, it cannot be used as a
confirmatory test for a positive reagent-strip glucose test. Clinitest should be reserved for patient
populations in whom non-glucose reducing substances need to be detected, such as in newborn
screening. A negative dipstick for glucose, but a positive Clinitest would suggest the presence of nonglucose sugar, requiring additional testing. This type of testing should be routine for all newborns. The
presence of ascorbic acid may lead to erroneous low results.
Normal—Health individuals normally will have no detectable sugars in their urine.
4. Ketones : (Section A)
Ketone bodies is a term used to describe three discrete but metabolically related chemicals: acetoacetic
acid, b-hydroxybutyric acid, and acetone. Reagent-strip testing for ketones uses the sodium
nitroprusside (sodium nitroferricyanide) reaction, which detects acetone and acetoacetic acid but not bhydroxybutyric acid, the primary ketone body.
Alkaline pH
Acetoacetic acid + Sodium nitroprusside
Purple
+ Glycine
color
Specific measurement of acetoacetic acid, b-hydroxybutyric acid, and acetone can be accomplished
using enzymatic procedures.
Clinical significance—Ketones are spilled into urine when the body cannot utilize glucose (as in
diabetes) and metabolize fatty acids. This catabolism is incomplete, resulting in the formation of large
amounts of acetoacetic acid, acetone and beta-hydroxybutyric acid (ketone bodies).
It is important to realize that the sodium nitroprusside reagent reacts primarily with acetoacetic acid;
acetone has only a 20% reactivity compared with acetoacetate, while b-hydroxybutyric acid does not
react at all in this reaction. So this method will always underestimate the total load of excreted ketone
bodies. However, this error is probably of no practical significance in the diagnosis or monitoring of
diabetes mellitus.
Normal—Health individuals normally will have no detectable ketones in their urine.
5. Blood and Myoglobin : (Section A)
The reagent-strip method for hemoglobin and myoglobin uses the peroxidase-like activity of these
heme-proteins to oxidize a chromogen (usually tetramethyl benzidine) to a colored product:
Alkaline pH
Hydrogen peroxide (H2O2)
Oxidized chromogen (blue)
+ Chromogen
+ H2O
A positive test indicates the presence of red blood cells in the urine (hematuria), free hemoglobin in the
urine (hemoglobinuria), or myoglobinuria. A microscopic urinalysis should be performed to confirm the
presence of intact erythrocytes.
Clinical significance—Oxidizing agents such as iodides and bromides in the urine may cause falsepositive results; large quantities of ascorbic acid (used in some antibiotics) in the urine may produce
false-negative results with some reagent strips. The peroxidase assay cannot distinguish between the
presence of hemoglobin or myoglobin in urine. The presence of intact red blood cells would strongly
suggest hematuria, but in appropriate clinical conditions, such as a crush injury, a specific test for
myoglobin will need to be performed.
Normal—Health individuals normally will have no detectable blood or myoglobin in their urine.
6. Bilirubin : (Section A)
The reagent-strip method for determining bilirubin involves a diazotization reaction:
Acid
Bilirubin glucuronide
+ Diazonium salt
Azobilirubin (brown)
The diazonium salts 2,4-dichlorobenzenediazonium-tetrafluroborate and 2,4-dichloroaniline are both
used for this test. While this reaction will occur with any form of bilirubin, only the water soluble,
conjugated form is present in urine. Thus the reaction is indicative of conjugated bilirubin in urine.
Clinical significance—The pigment bilirubin is formed by the degredation of heme. It is not excreted
into urine. Only the conjugated form of bilirubin, often termed direct bilirubin, is excreted into urine. In
most healthy individuals the amount of conjugated bilirubin excreted is not detected by the strips. In
cases when bilirubin is elevated and is conjugated, it will be detected by the test strip. A number of liver
diseases such as viral hepatitis will result in elevated urine bilirubin.
A negative bilirubin result on a urine from a patient believed to have increased serum bilirubin, and a
questionably positive result, such as from a highly colored urine, should be confirmed by using Ictotest
tablets (Ames Division, Miles Laboratories, Inc., Elkhart, IN). However, positive bilirubin results do
not need to be routinely confirmed. The Ictotest employs the same diazotization reaction as the reagent
strip, but may not give a false positive result with colored urines. False-negative results may occur if the
urine is not fresh, because urinary bilirubin may hydrolyze or oxidize when exposed to light.
Normal—Urine from healthy individuals does not contain detectable bilirubin.
7. Urobilinogen : (Section A)
The methods for detecting urinary urobilinogen differ with the manufacturer of the reagent-strip tests.
Ames (Miles Division, Bayer, Inc.) employ reagent-strip tests containing pdimethylaminobenzaldehyde which reacts in a simple color reaction with porphobilinogen, known as
the Ehrlich reaction. Boehringer Mannheim Diagnostics (BMD) reagent test strip use a reaction with 4methoxybenzene-diazonium-tetrafluroborate that is more specific for urobilinogen; urinary
urobilinogen reacts with the diazonium compound to form a red color.
Clinical significance—The Ehrlich reaction is not specific for urobilinogen, and false-positive findings
may result from other Ehrlich reagent positive compounds (porphobilinogen, p-aminosalicylic acid)
(PAS). However, the presence of compounds producing false positive results is usually not a clinical
problem. It should be noted that reagent strips will not detect the absence of urinary urobilinogen, that
is, the levels of urinary urobilinogen associated with decreased production of urobilinogen because of
hepatic obstructive disease will not be differentiated from the lowest detectable color (2 mg/L).
A fresh specimen is essential for the detection of urobilinogen, as it is a light-sensitive compound. The
preferred specimen for detecting and/or quantifying urinary urobilinogen is a 2-hour early afternoon
specimen. This collection takes into account the diurnal excretion pattern of urobilinogen.
Normal—A healthy person will contain from 2 to 10 mg/L of urobilinogen.
8. Nitrites : (Section A)
The nitrite test is used in urinalysis laboratories to detect bacteriuria. The reagent-strip nitrite test
measures the nitrite formed by the enzymatic reduction of nitrate by certain bacteria in urine. Two
reactions are currently being employed. In one (Ames), nitrite reacts with p-arsanilic acid under
reaction conditions of acid pH to form a diazonium compound; the diazonium product reacts with N-1naphthyl ethylenediamine to produce a pink color. The BMD product uses 3-hydroxy-1,2,3,4
tetrahydro-7,8-benzoquinoline and sulfanilamide in a similar reaction.
Clinical significance—A positive nitrite test is dependent upon the excretion of nitrate in the diet into
urine where it is converted to nitrite by gram negative bacteria.
The sensitivity of the nitrite test is about 60% when compared with microbiological procedures. There
are very few cases of false-positive nitrite results.
Normal—Urine from healthy individuals does not contain detectable nitrite.
9. Leukocyte esterase
Reagent-strip tests for pyuria (leukocytes in urine) are based on the presence of intracellular esterases of
bacteria. The esterases catalyze the hydrolysis of esters, releasing a product that reacts in a subsequent
reaction with a diazonium salt to produce a colored product. The Ames product uses a derivitized
pyrrole amino acid ester as the substrate for the esterases, while the BMD product employs an
indoxylcarbonic acid ester. The intensity of both color reactions is proportional to the number of
leukocytes in the specimen. The assay will detect both lysed and intact leukocytes. Sensitivities for the
two reagent-strip manufacturers are listed in the Table of Practical Sensitivities of Two Reagent Strip
Tests. False-positive results are seen with trichomonads and oxidizing agents; eosinophils and
histiocytes may also produce a positive reaction. Elevated levels of urinary protein and ascorbic acid
may result in false-negative values. The leukocyte test has been suggested as a screening test for pyuria;
only urine specimens that are positive for leukocytes by the esterase reagent strip test, would require the
more time-consuming microscopic examination for leukocytes.
Normal—Urine from healthy individuals does not contain detectable leukocytes.
MICROSCOPIC EXAMINATION OF URINE: (Section b & C)
The microscopic elements are present in urine (in suspension) are collected in the form of
deposit by centrifugation.
Microscopic Examination of Urine
General consideration
The microscopic examination is a valuable diagnostic tool for the detection and evaluation of
renal and urinary tract disorders and other systemic diseases.
Principle
The microscopic elements are present in urine (in suspension) are collected in the form of
deposit by centrifugation. A small drop of the sediment is examined by making a coverslip
preparation under microscope.
Requirements
1)
Centrifuge tubes or test tubes (10 * 75 mm)
2)
Glass slides
3)
Coverslips
4)
Pasteur pipettes
Instruments
1)
centrifuge
2)
microscope
Specimen
Freshly voided, midstream, morning urine.
Procedure
1)
Mix the urine and pour into a centrifuge tube (or small test tube) until it is ¾ full (about 5
ml).
2)
Centrifuge with another balanced test tube for 5 minutes at 2,500 RPM.
3)
Pour of the supernatant quickly and completely into another test tube (this can be used for
protein determination).
4)
Resuspend the deposit by shaking the tube.
5)
Place one drop of the deposit on a glass slide.
6) Cover it with a coverslip and mark it with the identification number.
7) Observe it first under low power objective in subdued light. This is obtained by partially
closing the iris diaphragm and then adjusting the condenser downward until satisfactory contrast
is obtained. Note the contents of various fields.
Note
a) In bright light some of the structures like hyaline casts will be missed.
b) The fine adjustment should be continuously adjusted up and down It enables the viewer to see
object and other structures which may be on different focal planes.
c) Switch to high dry objective and observe at least 10 to 15 different fields
Observations
The various findings observed in the sediment may be as follows:
No. Microscopic finding
Diagram
1) Leukocytes: The pus cells can enter in
urine anywhere from the glomerulus to the
urethra.
— Normal urine can contain 2-3 pus
cells/per h.p.f.
— These are mostly neutrophils
— Approximate diameter: 10- 12
Note: The addition of 2% acetic acid to the slide accentuate the nuclei of the cells.
— They shrink in hypertonic urine and swell up and lyse in hypotonic or alkaline urine.
No. Microscopic finding
2) Epithelial cells: These cells may
originate from any site in the genitourinary
tract from the proximal convoluted tubule
Diagram
to the urethra or from vagina.
— Normally few cells (3 to 5) per h.p.f.
from these sites can be found in the urine
due to sloughing off of old cells.
— Three main types of epithelial cells may
be recognized: (a) tubular (b) transitional
and (c) squamous
a) Tubular epithelial cells: These are
slightly larger than leukocytes and contain
large round nucleus.
— They may be cuboidal, flat or columnar
b) Transitional epithelial cells
— These are two to four times as large as
white cells
— They may be pear shaped or round O
these cells may contain two nuclei
c) Squamous epithelial cells: These are
large, flat and irregularly shaped
— They contain abundant cytoplasm and
small central nuclei.
3) Erythrocytes
— In fresh urine these cells have a normal,
pale or yellow appearance
— They appear smooth, biconcave disks
about 7 diameter and 2 thick
— They do not contain nuclei
— In dilute (or hypotonic) urine the red
cells swell up and lyse
— Lysed cells appear as colorless circles
(ghost cells)
In hypertonic urine the red cells crenate.
Note: Yeast cells can be mistaken for RBCs. Yeast cells are ovoid and frequently contain buds.
No. Microscopic finding
4) Casts: Urinary casts are formed in the
lumen of the tubules of the kidney. The
renal tubules secrete a mucoprotein called
Tamm-Horsfall protein which is believed
to form the basic matrix of all casts
Casts can form as the result of - a)
Precipitation of gelatin of Tamm Horsfall
mucoprotein
b) Clumping of cells on other material
within protein matrix
c) The adherence of cells or cellular
material to the matrix
d) Coagulation of material within the
lumen
Cast formation takes place in the distal and
collecting tubules (since the formation of
casts require acidic conditions and high
solute concentration) Casts dissolve in
alkaline urine
— Casts have nearly parallel sides rounded
or blunted ends They may be convoluted,
straight or curved.
A) Granular casts: These always indicate
significant renal disease. The casts are
present due to the degeneration of cellular
casts or due to direct aggregation of serum
Diagram
proteins in a Tamm-Horsfall mucoprotein
matrix
B) Hyaline casts:
homogeneous,
They are colorless, transparent and with
rounded ends.
Note: A few hyaline casts may be present in normal urine.
CEREBROSPINAL FLUID EXAMINATION : (Section C)
Basic Facts
Cerebrospinal fluid (CSF) examination is a laboratory test that
analyzes the fluid surrounding the brain and spinal cord.
The fluid is usually extracted during a procedure called a
lumbar puncture.
CSF examination helps physicians diagnose myriad
conditions, including infection, brain tumors, spinal tumors.
Cerebrospinal fluid (CSF) examination is a laboratory test that analyzes the fluid surrounding the
brain and spinal cord. Cerebrospinal fluid is a clear fluid that cushions the brain to protect it from
injury and flushes toxins out of the brain. The fluid is usually extracted from the spinal cord
during a procedure called a lumbar puncture (LP). The procedure is performed in the lower back,
called the lumbar region.
Analyzing the CSF can help physicians diagnose the following conditions:

Infections;

Brain and spinal tumors;

Cancerous cells or tumors in the meninges (the membrane that surrounds the brain);

Dementia;

Multiple sclerosis;

Guillain-Barre syndrome;

Vasculitis; and

Subarachnoid hemorrhage.
When analyzing CSF, technicians evaluate the following characteristics and substances in the
fluid for signs of a condition:

Clarity and color;

Bacterial cultures;

White blood cells;

Protein;

Glucose;

Chloride;

Lactic dehydrogenase; and

Cancerous cells.
PRE-TEST GUIDELINES
No fasting is required prior to a lumbar puncture. The physician may instruct the patient to use
the restroom prior to the procedure.
Prior to the test, the physician will often perform a neurologic assessment that tests the patient's
legs for strength, sensation, and movement.
RISK FACTORS
Patients with an infection near the insertion site or patients who have increased pressure in the
brain can place patients at greater risk for complications following the procedure. The physician
may recommend that these patients not have an LP performed.
WHAT TO EXPECT
The patient wears a hospital gown and lies on their side with their legs pulled up toward their
chest. In some cases, patients may sit on an exam table and lean forward with their head resting
on pillows in their lap.
After cleaning the area and giving the patient a local anesthetic, the physician inserts a needle
between two vertebrae in the patient's lower back until it enters the spinal canal. When the needle
is in place, the physician may take a pressure reading of the CSF and then withdraws the CSF,
which is sent to the laboratory for analysis.
POST-TEST GUIDELINES
Patients are sometimes instructed to lie on their back for 6 to 12 hours. To help avoid a lumbar
puncture headache, patients should minimize sitting or standing for long periods during the first
12 hours after the test. Patients are instructed to drink plenty of liquids to help replace the CSF.
POSSIBLE COMPLICATIONS
Headache after a lumbar puncture is the most common post-procedure complication. Other side
effects may include pain or an aching feeling in the patient's neck or low back, nausea, vomiting,
or ringing in the ears.
Complications from a lumbar puncture are rare; however, a lumbar puncture can make the
following conditions or symptoms worse:

Brain herniation;

Spinal cord compression;

Subarachnoid bleeding;

Double vision;

Back pain; and

Radicular symptoms.
CSF Analysis Test by blogmin: Also known as: Spinal fluid analysis
Related tests: Glucose, Total Protein, CBC (Complete Blood Count), Lactate, Protein
Electrophoresis, Antibody Tests, AFB Smear and Culture, Blood Culture, Herpes, Lyme
Disease, Rubella, Syphilis, West Nile Virus
CSF Analysis: At A Glance
Why get tested?
To diagnose a disease or condition affecting the central nervous system (CNS) such as bleeding
within the brain or skull, cancer, autoimmune disorder or infection
When to get tested?
When your doctor suspects that your symptoms are due to a condition or disease involving your
central nervous system
Sample required?
A sample of cerebrospinal fluid (CSF) is collected by a doctor from the lower back using a
procedure called a lumbar puncture or spinal tap.
CSF Analysis: The Test Sample
What is being tested?
Cerebrospinal fluid (CSF) is a clear watery liquid filtrate that is formed and secreted by the
choroid plexus, special tissue that has many blood vessels and lines the small cavities or
chambers (ventricles) in the brain. CSF flows around the brain and spinal cord, surrounding and
protecting them. It is continually produced, circulated, and then absorbed into the blood system.
About 500 mL is produced each day. This rate of production means that all of the CSF is
replaced every few hours.
A protective blood-brain barrier separates the brain from circulating blood and regulates the
distribution of substances between the blood and the CSF. It helps keep large molecules, toxins,
and most blood cells away from the brain. Any condition that disrupts this protective barrier may
result in a change in the normal level or type of constituents of CSF. Because CSF surrounds the
brain and spinal cord, testing a sample of CSF can be very valuable in diagnosing a variety of
conditions affecting the central nervous system (CNS). Though a sample of CSF may be more
difficult to obtain than, for example, urine or blood, the results may reveal more directly the
cause of CNS symptoms.
For example, infections and inflammation in the meninges (called meningitis) or the brain (called
encephalitis) can disrupt the blood-brain barrier and allow white and red blood cells and
increased amounts of protein into the CSF. Meningitis and encephalitis can also lead to the
production of antibodies. Immune diseases that affect the CNS, such as Guillain-Barré
Syndrome, and multiple sclerosis can also produce antibodies that can be found in the CSF.
Cancers such as leukemia can lead to an increase in CSF white blood cells (WBCs), and
cancerous tumors can result in the presence of abnormal cells. These changes from normal CSF
constituents make the examination of cerebrospinal fluid valuable as a diagnostic tool.
CSF analysis usually involves an initial basic set of tests performed when CSF analysis is
requested:

CSF color, clarity and pressure during collection

CSF protein

CSF glucose

CSF cell count

CSF differential

If infection is suspected, CSF gram stain and culture
A wide variety of other tests may be ordered as follow-up depending on the results of the first set
of tests. The specific tests that are ordered may also depend on the signs and symptoms of the
patient and the disease the doctor suspects is the cause. Each of these tests can be grouped
according to the type of exam that is performed:

Physical characteristics -includes measurement of the pressure during sample collection
and the appearance of the CSF.

Chemical tests -this group refers to those tests that detect or measure the chemical
substances found in spinal fluid. CSF is basically an ultafiltrate of the blood, so it can
also be affected by what is going on in the blood. Normally, certain constituents of CSF
such as protein and glucose are a percentage of blood levels, so CSF levels are often
evaluated in relation to blood levels.

Microscopic examination (Cell count and differential)-any cells that may be present are
counted and identified by cell type under a microscope.

Infectious disease tests -numerous tests can be done to detect and identify
microorganisms if an infection is suspected.
How is the sample collected for testing?
A sample of cerebrospinal fluid (CSF) is collected by a doctor from the lower back using a
procedure called a lumbar puncture or spinal tap. Often, three or more separate tubes of CSF are
collected, and multiple tests may be run on the different samples.
CSF Analysis: The Test
How is it used?
Cerebrospinal fluid (CSF) analysis may be used to help diagnose a wide variety of diseases and
conditions affecting the central nervous system (CNS). They may be divided into four main
categories:

Infectious diseases such as meningitis and encephalitis-testing is used to determine if the
cause is bacterial, tuberculous, fungal or viral, and to distinguish it from other conditions;
may also be used to detect infections of or near the spinal cord or to investigate a fever of
unknown origin.

Bleeding (hemorrhaging) within the brain or skull

Diseases that cause inflammation or other immune responses such as antibodies-these
may include autoimmune disorders such as Guillain-Barré syndrome or sarcoidosis or
diseases that cause the destruction of myelin such as multiple sclerosis

Tumors located within the CNS (primary) or metastatic cancer
When is it ordered?
CSF analysis may be ordered when a doctor suspects that a patient has a condition or disease
involving their CNS. A patient’s medical history may prompt the request for CSF analysis. It
may be ordered when a patient has suffered trauma to the brain or spinal cord, has been
diagnosed with cancer that may have spread (metastatic) or has signs or symptoms suggestive of
a condition involving their CNS.
The signs and symptoms of CNS conditions can vary widely and many overlap with a variety of
diseases and disorders. They may have sudden onset, suggesting an acute condition such as CNS
bleeding or infection or may be slow to develop, indicating a chronic disease such as cancer or
multiple sclerosis.
Depending on a patient’s history, doctors may order CSF analysis when some combination of the
following signs and symptoms appear:

changes in mental status and consciousness

confusion, hallucinations or seizures

muscle weakness or lethargy, fatigue

nausea

flu-like symptoms that intensify over a few hours to a few days

fever or rash

sudden, severe or persistent headache or a stiff neck

sensitivity to light

numbness or tremor

dizziness

difficulties with speech

difficulty walking, lack of coordination

mood swings, depression

infants may be irritable, cry when they are held, have body stiffness, refuse food, and
have bulging fontanels (the soft spots on the top of the head)
What does the test result mean?
CSF usually contains a small amount of protein and glucose and may have a few white blood
cells (WBCs).
Any condition that disrupts the normal pressure or flow of CSF or the protective ability of the
blood/brain barrier can result in abnormal results of CSF testing. For detailed explanations of
what various tests results may mean, see the sections on:

CSF physical characteristics

CSF chemical tests

CSF microscopic examination

CSF infectious disease tests
Is there anything else I should know?
Multiple tubes of CSF are often collected during a lumbar puncture to ensure the quality of
samples for testing.
Bacterial and amoebic meningitis are medical emergencies. Your doctor must rapidly distinguish
between these conditions, the generally more mild viral meningitis, and other conditions.
Because prompt treatment is crucial, your doctor may start you on a broad-spectrum antibiotic
before the diagnosis has been definitely determined.
To help diagnose your illness your doctor may want to know what recent illnesses and
vaccinations you may have had, what symptoms you are experiencing, whether you have been in
contact with any ill people, and what places you have recently traveled to.
CSF Analysis: Common Questions
1. What is a lumbar puncture (spinal tap) and how is it performed? The lumbar puncture is a
special but relatively routine procedure. It is usually performed while you are lying on your side
in a curled up fetal position, but may sometimes be performed in a sitting position. It is crucial
that you remain still during the procedure. Once you are in the correct position, your back is
cleaned with an antiseptic and a local anesthetic is injected under the skin. When the area has
become numb, a special needle is inserted through the skin, between two vertebrae, and into your
spinal canal. It is gently advanced until it enters the subarachnoid space (located between the
arachnoid and pia mater layers of the meninges) and cerebrospinal fluid (CSF) begins to flow.
You may be asked to straighten out your legs at this point and relax your muscles. It is important
not to move unless you are instructed to do so. An “opening” or initial pressure reading of the
CSF is obtained. The doctor then collects a small amount of CSF in multiple sterile vials. A
“closing” pressure is obtained, the needle is withdrawn, and a sterile dressing and pressure are
applied to the puncture site. You will then be asked to lie quietly in a flat position, without lifting
your head, for one or more hours to avoid a potential post-test spinal headache.
The lumbar puncture procedure usually takes less than half an hour. For most patients it is a
moderately uncomfortable to somewhat painful procedure. The most common sensation is a
feeling of pressure when the needle is introduced. Let your doctor know if you experience a
headache or any abnormal sensations, such as pain, numbness, or tingling in your legs, or pain at
the puncture site.
The lumbar puncture is performed low in the back, well below the end of the spinal cord usually between lumbar (L) vertebrae L4 and L5. There are spinal nerves in the location
sampled, but they have room to move away from the needle. There is the potential for the needle
to contact a small vein on the way in. This can cause a “traumatic tap,” which just means that a
small amount of blood may leak into one or more of the samples collected. While this is not
ideal, it may happen a certain percentage of the time. The evaluation of your results will take this
into account.
Blood from the collection procedure (spinal tap) may contaminate the first portion of CSF
sample that is collected. However, there are usually three or more separate tubes used to collect
CSF samples during one spinal tap procedure. The last tube that is collected during a spinal tap is
least likely to have blood cells present due to the procedure and is usually the sample used to test
for the presence of blood cells in the CSF. Likewise, the last sample collected is used for
infectious disease testing since it will not be contaminated with microorganisms from inserting
the needle through the skin.
2. Are there other reasons to do a lumbar puncture? Yes. Sometimes it will be performed to
introduce anesthetics or medications into the CSF. Repeated punctures are sometimes used to
decrease CSF pressure.
3. Why do I need a spinal tap-why can’t my blood or urine be tested? Spinal fluid, obtained
during a spinal tap, is often the best sample to use for conditions affecting your central nervous
system because your CSF surrounds your brain and spinal cord. Changes in the elements of your
CSF due to CNS diseases or other serious conditions are often first and most easily detected in a
sample of your spinal fluid. Tests on blood and urine may be used in conjunction with CSF
analysis to evaluate your condition.
4. What other tests may be done in addition to CSF analysis? Other laboratory testing that may
be ordered along with or following CSF testing includes:

Blood culture to detect and identify bacteria in the blood

Cultures of other parts of the body - to detect the source of the infection that led to
meningitis or encephalitis

Blood glucose, total protein - to compare with the concentration of CSF glucose and
protein

CBC (complete blood count) - to evaluate cell counts in blood

Antibodies for a variety of viruses, such as West Nile Virus

ESR (Erythrocyte Sedimentation Rate) and CRP (C-reactive Protein) - indication of
inflammation
· CMP (Comprehensive Metabolic Panel) - a group of tests used to evaluate electrolyte balance
and organ function
CHEMICAL EXAMINATION OF CEREBROSPINAL FLUID: ((Section B)
In addition to the cell count, bacteriological examination and Wassermann reaction, the
following chemical tests are commonly carried out on cerebrospinal fluid : determination of
glucose, chlorides, and protein, qualitative test for globulin, and the Lange colloidal gold curve.
It is only rarely that other tests such as estimation of urea and calcium are requested. The
concentration in cerebrospinal fluid of certain drugs such as the sulphonamides may sometimes
be required.
The fluid ordinarily examined is the lumbar fluid, but occasionally cisternal and
ventricular fluids are taken. Any differences between these fluids will be indicated under the
various constituents.
Before considering the methods used in examining these fluids it will be useful to say
something about their appearance.