Examination of Body Fluids (Urinalysis)
Examination of Body Fluids (Urinalysis)
Examination of Body Fluids (Urinalysis)
Body F luid s
Woon Sung Thong, FMIMLS
Past President, Malaysian Institute of Medical Laboratory Sciences
Laboratory Manager, Biolife Lab Sdn Bhd
Body Fluids
• Urine
• Seminal Fluid
• Amniotic Fluid
• Cerebrospinal Fluid
• Synovial Fluid
• Pleural, Pericardial and Peritoneal Fluid
• Fecal analysis
Urine Collection
First morning
*voids before going to bed
*formed elements are more stable
*unsuitable for cytology studies
Random
• ? Second voiding
Collect ion
Techniques
Routine Midstream
• At pre-employment medical
examinations
• Routinely at physician office and
medical clinics
• Annual medical examination
Microscopic Changes
RBC, WBC, Casts
*decreased due to disintegration
especially in alkaline urine
RBC decreased after 6 hours
WBC decreased 50% within 3 hours
Hyaline and granular casts decreased after 2 hours
Bacteria
*increased due to bacterial proliferation
Potentia l C hanges
in Unpre serv ed
Urine
Microscopic Changes
• Precipitation of uric acid, calcium
phosphate and calcium oxalate
• Yeast cells develop pseudo-mycelia
• Spermatozoa become immobile
• Trichomonas become immobile,
maybe counted as WBC
• Contamination by air borne particles
Urine Examinatio n
Preservatives
Most preservatives prevent bacterial
growth and loss of glucose (eg.
Stabilur, formalin)
No preservatives can prevent destruction
of bilirubin, urobilinogen or occult
blood.
Use of preservatives may increase SG,
minor effects on pH and may inhibit
leukocyte esterase reaction.
Urine Examinatio n
• Physical Examination
• Chemical Examination
• Microscopic Examination
Urine - Phys ical
Examination
• Colour - urochrome, urobilin, uroerythrin
• Clarity
Clear
Slightly cloudy
Cloudy
Turbid
• Odour
Physical Tests
• Color
Normal color range
from straw, pale
yellow, to amber.
Abnormal color:
red - RBCs
beer-brown - bilirubin
orange, blue, green
- drug, dye or food
CO LO UR
ITEMS
Colour Constituent Comments
• Turbidity
Normal is essentially
clear.
Cloudy urine:
amorphous salts
- non pathologic
bacteria, blood cells
- pathologic
Causes of Tu rbidity
• Reaction:
– Pseudoperoxidase action of Hgb myoglobin catalyzes
the oxidation of chromogens to produce a color change
• False negatives:
– formalin, excess nitrites (>2.2 mmol/l), elevated SG, ph
<5.1, captopril, ascorbic acid
• False positives:
– oxidizing detergents, microbial peroxidase (UTI),
dehydration, exercise, hemoglobinuria, myoglobinuria,
menstrual contaminants, proteinuria (>5 g/l)
Blood
•Cancer •Inflammation of
•Trauma kidneys
•Stones •Benign prostrate
•Infections enlargement
•Obstructions •Warfarin therapy
•Viral infections
Blood
• Reaction:
– Bilirubin in the urine couples with a diazonium salt in an acid
medium
• False negatives:
– samples exposed to light, excess levels of ascorbic acid.and
nitrite, selenium, chlorpromazine
• False positives:
– highly colored metabolites of drugs eg pyridium
Bilirubin
• Reaction:
– double sequential enzyme reaction of glucose oxidase and
peroxidase-reacts with a chromogen to produce the final
color.
• False negatives:
– elevated specific gravity, uric acid, ascorbic acid
• False positives:
– presence of oxidizing agents, ketones, levodopa
Glucose
• Reaction:
– Leukocyte esterase, present in granulocytes,
catalyzes the reaction of the chromogens to produce
a color change.
• False negatives:
– cephalexin and gentamicin concentrations; elevated
SG, glucose, ketone and protein concentrations,
ascobic acid
• False positives:
– vaginal contaminants, drugs or foods that color the
urine red
Nitrites
• Reaction:
– Nitrates in the urine are converted to nitrites by the action of
gram-negative bacteria. These nitrites then react to form a
diazonium salt which in turn reacts with a chromogen to
produce the final color.
• False negatives:
– Elevated SG, urobilinogen, pH <6.0, excess ascorbic acid
• False positives:
– presence of red dyes or other chromogens, contamination
pH
• Reaction:
– double indicator system detects the amount of
hydrogen ions in the urine to produce a color change.
• Interferences:
– If excess urine is left on the reagent strip, a
phenomenon known as “runover” may occur. The urine
from one reagent area carries reagent onto the pH test
area and changes the result erroneously.
pH
• Reaction:
– based on “protein error of indicators” - because protein
carries a charge at physiologic pH, their presence will elicit a
pH change
• False negatives:
- acidic or diluted urine, primary protein is not albumin
False positives:
– Alkaline or concentrated urine, quaternary ammonia
compounds
Protein
• Reaction: ionic SG
– based on the change of an indicator color in the
presence of high concentrations of various ions.
• False negatives:
– highly alkaline urine
• False positives:
– Proteinuria, Dextran solutions,IV radiopaque dyes,
Specific Gravity
• Reagent:
– urobilinogen reacts with a chromogen to form an azo
dye which appears as various shades of pink or purple.
• False negatives:
– excess nitrites; presence of formalin
• False positives:
– presence phenazopyridine; very warm urine, elevated
nitrite levels
Urobilinogen
• Leucocyte
• RBC
• Protein
• Nitrite
• pH > 7.0
Micr oscopic
Examination
Sediment examination
• Cells
– blood cells; RBCs and WBCs
– epithelial cells; renal, transitional, squamous
• Casts
– Hyaline
– Waxy
– Inclusion casts; Granular, Fatty
– Cellular; RBC, WBC, and Epithelial casts
• Bacteria, Fungi, and Parasites
• Crystals
Methods for Examining
Urine sediment
• Increased numbers
are seen:
– renal diseases
– urinary tract infection
• when accompanied by
casts:
– renal in origin
Squamous
Epithelial cells
• Translucent with
brightfield microscopy
• increased numbers:
– Pyelonephritis, chronic
renal disease
– transiently with exercise
– May be a normal finding
Waxy cast
• Associated with
tubular inflammation
and degeneration
• observed frequently
with chronic renal
failure
Granular casts
• Commonly seen
when there is heavy
proteinuria
• a feature of
nephrotic syndrome
• hypothyroidism
Red Blood Cell casts
• Diagnostic of
glomerular disease
• glomerular damage
allows RBCs to
escape into the
tubules
White Blood Cell casts
Bacteria Yeast
Trichomonas Yeast
Clue Cells
Crystals
Cystine Bilirubin
Tyrosine Cholesterol
Procedure for Urine
Microscopy
Report
slide preparation
writing report microscopy
Quantitative ME
Centrifugation:
3 mm
1 mm W W
Depth of chamber
= 0.1mm
W W
Fuchs-Rosenthal counting chamber
Small square
Medium square
Large square
1 medium square
= 0.2 uL
16 middle square
Depth of chamber
= 0.2 mm 1 large square
= 3.2 uL
1 mm
1 mm
Fuch Rose nth al vs Neubauer
fo r Qu antita tive Urin e
Mic roscopy
• Advantage of Fuch Rosenthal over Neubauer
– analysis volume of Neubauer is half of Fuch
Rosenthal
• concentration of urine formed elements is very low
compared with those of hematology.
• For urinalysis, the more volume, the better results
– some urine formed elements are large (ie casts),
these might clog the chamber Depth of chamber
• the deeper the depth, the better
Cells /uL = total cells counted / [mm2 counted x 0.1 mm or 0.2mm]
Initial vol 12 ml 12 ml 12 ml
Sediment Conc 15 : 1 12 : 1 30 : 1
Area of viewing 36 sq mm 32 sq mm 90 sq mm
No of LPF 11 10 28