Interpretation of
abnormalities in urine
Shiva Seyrafian
Isfahan University of
Medical Sciences
20/8/1391
11/10/2012
The aim of this lecture
1.
Urine tests (GFR and Proteinuria)
2.
Urinalysis and urine sediment
What you should learn at the end of this
lecture
1) To know what are the urine tests.
2) How do we measure urine tests?
3) What is urinalysis?
4) How do we exam urinalysis?
5) What is the benefit of learning urine tests and
urinalysis?
Tests of Glomerular
Filtration Rate
• Creatinine Clearance
• Normal finding :
male : 90-139 ml/ min
female : 80-125 ml /min
Calculation of creatinine clearance
1.
24 hour urine collection
• C cr = U cr x V/ P cr
2- Cockroft- Gault Formula
• C cr = (140 – age in years) x ( lean body
weight in Kg) / S cr x 72
• For women multiply final value by 0.85 OR
put 85 instead of 72.
3- Modification of Diet in Renal Disease
Formula
• GFR = 186 X (Cr) -1.154 x age -0.203 x [0.742 (if
woman)]
• Normal range = 95 -105 ml/min/ 1.73 m2
• Low Cr clearance:
1. Acute renal failure (ATN, AIN, Acute GN)
2. Chronic renal failure: Chronic
glomerulonephritis, chronic HTN, DM
3. UTO
4. Old age
Tests that predict kidney disease
Albumin/ Creatinine Ratio
(ACR or Microalbumin)
Albumin Creatinine Ratio
(Microalbumin)
In health, there is very little or no
albumin in the urine
Most dip sticks report albumin at
greater than 150 mg/L
Normal microalbumin: 30 -300
mg/24hrs
Urinary Albumin – cont’d
 Detection of low levels of albumin (even
if below dipstick cut-off) is predictive of
future kidney disease with diabetes
 Very significant variation usually requires
repeat collections
 Microalbuminuria: DM, Hypertension and
early GN
Urinalysis
• The most commonly performed
• As a screening procedure for asymptomatic
individual.
• To confirm the presence of renal disease, diabetes,
or, more rarely, liver disease.
• can be performed in emergency rooms, outpatient
clinics, private physicians' offices, and patients'
homes.
Urinalysis
• Three types of urinalysis can be
performed: 1-dipstick urinalysis, 2microscopic urinalysis, 3-cytodiagnostic
urinalysis (specialized analyses).
1,2= routine urinalysis
• Cytodiagnostic urinalysis is more timeconsuming than traditional microscopic
analysis
Specimen Collection
• Midstream, catheterized, suprapubic aspiration
• Ideally within 30 minutes of collection
• Specimens > 2 hours old are inaccurate
• Can be refrigerated at 4oc up to 6 hours
• Amorphous urate may precipitate
• Should return to room temperature
Urinalysis
1. macroscopic analyses consisting of
physicochemical determinations
(appearance, specific gravity), and
multi-parameter reagent-strip
measurements of biochemical
constituents,
2. microscopic examination of urinary
sediment: hematuria, pyuria, cylindruria
(casts), crystalluria, and others.
Physical Examination of Urine
physicochemical determinations
i.
Volume (750 -2000 ml/ day)
ii. Odor (Mild, inoffensive odor)
iii. Appearance (color and turbidity)
Bad odor to the urine
• Either cystitis or vaginitis
• Look for:
-Lost and forgotten tampon
-Yeast
-Trichomonas
-Bacterial vaginosis
-Asparagus eating
-Ampicillin intake
Color of urine
urine color due to
Metronidazol
Physical Examination of Urine
physicochemical determinations
iv. Specific gravity: refractometer [measures
the density (mass per unit volume) of the
suspended particles]
The normal range is 1.003 to 1.035 g/mL. A
value of 1.020 or greater indicates good renal
function
Physical Examination of Urine
physicochemical determinations
• V. Osmolality:
osmometer ( the number of
particles per unit mass).
• The healthy kidney is capable of
producing urine with a wide range of
concentrations, from 50 to 1200
mOsm/kg. Normally, a urine's osmolality
will range from approximately one-sixth
to four times the osmolality of normal
serum (280 to 290 mOsm/kg).
Physical Examination of Urine Reagent-strip testing
urine pH
• The urinary pH range is usually 4.7 to 7.8.
Extremely acidic or alkaline urine usually
indicates a poorly collected specimen.
• More acidic with increased meat intake
• More alkaline with vegetarian diet
• High pH with prolonged storage or urea
splitting organisms, diuretic therapy,
vomiting, ,gastric suction and alkali therapy.
Chemical Examination of Urine Reagent-strip testing
Blood and myoglobin
 Normally not detectable in the urine
 Oxidizing agents such as povidone - iodine
and myoglobin will cause a positive
reaction
 Positive dipstick without RBCs suggests
hemolysis or rhabdomyolysis.
• Chemical Examination of Urine
Reagent-strip testing
• Bilirubin: no detectable in the urine
• Urobilinogen: 2-10 mg/L
 Only conjugated bilirubin is passed into the urine.
 In hemolysis urine urobilinogen is often positive
 False positive test for urine bilirubin can occur if the
urine is contaminated with stool
 Prolonged storage and exposure to light can lead to false
negative results.
Chemical Examination of Urine
Reagent-strip testing
• Sugars: not detectable sugars in the
urine.
• Ketones: not detectable in the urine
• Nitroprusside reaction used to detect
ketones (acetone and acetoacetate)
• b-OH butyrate is not normally detected
Chemical Examination of Urine
Reagent-strip testing
• Nitrites: detect bacteriuria: measures the nitrite
formed from converaion of nitrates to nitrites by
certain bacteria in urine.
• Normally does not contain detectable nitrite.
• False negative:
• Ascorbic acid and high urine SG
• Low urinary nitrates (due to diet)
• Rapid transit of urine (takes 4 hrs to convert nitrates to
nitrites in bladder )
• Degradation of nitrites (prolonged storage of urine)
• Gram positives, N. gonorrhea, M. TB.
Chemical Examination of Urine
Reagent-strip testing
• Leukocytes: pyuria (leukocytes in urine)
are based on the presence of intracellular
esterases released from lysed
granulocytes, .
• Normally does not contain detectable
leukocytes.
• False positive
• Long standing urine, more granulocyte lysis
• Vaginal contamination
Normal Proteinuria
• 30 to 150 mg/day
• Usually only small proteins (<20,000 daltons) pass across
capillary wall and most are reabsorbed in prox. tubules e.g.,
a2-microglobulin, apoproteins, enzymes, peptide hormones
• Tamm-Horsfall protein (uromodulin)
• High m. wt. 23 x 106 daltons glycoprotein
• Thick ascending limb and distal convoluted tubule
• IgA and urokinase in small amounts
• Protein :
False Negative Results
proteins
proteins
False Positive Result
Bence Jones
Heavy-chain
Alkaline urine
• Sulfosalicylic acid:
False negative
Alkaline urine
Microscopic Examination
Of Urine
Microscopic Examination
• Cells
• Casts
• Crystals
• Organisms
• Artifacts
Chemical Examination of Urine –
Microscopic examination of urine
• Red blood cell: Less than 3 erythrocytes per highpowered field
• White blood cell: Less than 5 leukocyte, per
three high-power fields (400X). 3000 cells/mL
• Twice RBC size, cytoplasmic granulation
• Inflammation or infection
• Eosinophils, best seen with Hansel’s stain or
Wright’s stain
RBC
WBC
Epithelial Cells
• Squamous, transitional, renal epithelial
cells
• Squamous epithelial cells
• Large flat, 30 to 50 micrometers in
diameter
• Nucleus to cytoplasm size ratio is 1:6
• Contamination from distal genital tract
Squamous epithelial
cell
Renal epithelial cell
Casts
• Renal casts are cylindrical structures that
are formed in the nephron and excreted in
the urine. Casts are significant because of
their localizing value. Casts are composed
of mucoprotein, or uromucoid, (TammHorsfall protein), which is always present
in urine, usually in solution.
Casts
• The Tamm- Horsfall mucoprotein is
produced by the tubular epithelial cells
lining the ascending limb of the loop of
Henle.
• Casts are formed when urine stasis exists,
which allows uromucoid to precipitate.
• Increased concentrations of protein and
salts and a low urine pH all contribute to
cast formation.
Casts
• Casts: Less than 3 hyaline casts, zero to one granular
cast, and no pathological cast per low-power field
(100X).
• Casts include:
• RBC
• WBC
•
•
•
•
•
Epithelial
Granular
Hyaline
Fatty
Waxy
RBC Cast
RBC Cast
WBC Cast
WBC Cast
Hyaline cast
Granular cast
Waxy cast
Fat droplets, Oval fat bodies
in nephrotic syndrome
Nephrotic syndrome
Renal epithelial cell cast in ATN
Crystals
• Least clinically important
• Crystals exist with/without presence of
stones
• Cooling urine will have some crystal
precipitate
• More in concentrated urine
• Crystals: Small numbers of common,
nonpathological crystals, such as uric acid or
phosphate crystals.
No specific disease,
Present in Ca Ox stones
and ethylene glycols
toxicities
No
specific
disease,
Present
in Ca Ox
stones
and
ethylene
glycol
toxicities
No specific disease
Present in uric
acid stones
No specific disease
Present in uric acid
stones
Specific in
cystinuria
Coffin lid
• Fungus, parasites, or viral inclusion cells:
None.
• Bacteria: Less than 10 bacteria per highpower field (400X).
Summary
1.
Urinalysis is used as a routine test.
2.
GFR, proteinuria and urinalysis are the most important
tests.
3.
cellular casts are more important than crystals.