AUBF PHYSICAL EXAMINATION OF URINE

1. ANALYSIS OF URINE AND OTHER BODY
FLUIDS (part 1)
PHYSICAL AND
CHEMICAL
EXAMINATION
OF URINE
Prepared by:
LGGRMT

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The physical examination of urine includes the determination of the urine
color, clarity, and specific gravity.
● preliminary information concerning disorders such as glomerular
bleeding, liver disease, inborn errors of metabolism, and urinary tract
infection.
● Measurement of specific gravity aids in the evaluation of renal
tubular function.

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COLOR
● may be due to normal metabolic functions,
physical activity, ingested materials, or
pathologic conditions.
● Urochrome = a pigment responsible to the
yellow color of urine.
Excretion of which is generally proportional
to the metabolic rate.
● intensity of the yellow color in a fresh urine
specimen can give a rough estimate of
urine concentration.

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COLOR
● Uroerythrin = a pink pigment, is most
evident in specimens that have been
refrigerated, resulting in the precipitation of
amorphous urates.
● Uroerythrin attaches to the urates,
producing a pink color to the sediment
● Urobilin = an oxidation product of the
normal urinary constituent urobilinogen,
imparts an orange-brown color to urine that
is not fresh.

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ABNORMAL
URINE COLOR
Dark Yellow/Amber/Orange
● There might be a presence of the abnormal
pigment bilirubin.
● If bilirubin is present = can be detected during
chemical examination of urine.
● Yellow foam = suspected by the presence of
bilirubin.
● Normal urine = small amount of rapidly
disappearing foam when shaken.
● White foam = increased conc. of protein.

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ABNORMAL
URINE COLOR
Dark Yellow/Amber/Orange
❖ Yellow orange
- Concentrated urine
- Urobilin in excess bilirubin
- Dehydration, fever
- No yellow foam (normal)
- Administration of phenazopyridine (Pyridium)
or azo-gantrisin compounds to persons with
urinary tract infections

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ABNORMAL
URINE COLOR
Red/Pink/Brown
● most common causes of abnormal urine color
is the presence of blood.
● Red blood cells (RBCs) remaining in an acidic
urine for several hours produce a brown urine
due to the oxidation of hemoglobin to
methemoglobin
● Fresh brown urine containing blood = indicate
glomerular bleeding resulting from the
conversion of hemoglobin to methemoglobin
● Hematuria (presence of red blood cells (RBCs)

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ABNORMAL
URINE COLOR
Red/Pink/Brown
● Hemoglobin & myoglobin = produce a red
urine. (+) chemical result for blood.
➢ RBCs - red & cloudy
➢ Hemoglobin/Myoglobin - red & clear.
💡distinguishing between hemoglobinuria and
myoglobinuria may be possible by examining
the patient’s plasma.
Hemoglobinuria = in vivo breakdown of RBCs is
accompanied by red plasma.

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ABNORMAL
URINE COLOR
Red/Pink/Brown
Myoglobinuria = presence of an excess amount of
myoglobin in the urine. It is mostly caused by muscle
breakdown, releasing a high amount of myoglobin in
the blood.
➢ Myoglobin is more rapidly cleared from the
plasma.
➢ Fresh urine containing myoglobin frequently
exhibits a more reddish-brown color than
hemoglobin.
● Urine specimens containing porphyrins: resulting
from the oxidation of porphobilinogen to
porphyrins.
💡referred to as having the color of port wine.

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ABNORMAL
URINE COLOR
Red/Pink/Brown
NON PATHOLOGIC CAUSE:
➢ Menstrual contamination,
➢ Ingestion of highly pigmented foods
➢ Medications (rifampin, phenolphthalein, phenindione,
and phenothiazines)
➢ genetically susceptible persons, eating fresh beets
causes a red color in alkaline urine
➢ Ingestion of blackberries can produce a red color in
acidic urine.

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ABNORMAL
URINE COLOR
Red/Pink/Brown
NON PATHOLOGIC CAUSE:
➢ Menstrual contamination,
➢ Ingestion of highly pigmented foods
➢ Medications (rifampin, phenolphthalein, phenindione,
and phenothiazines)
➢ genetically susceptible persons, eating fresh beets
causes a red color in alkaline urine
➢ Ingestion of blackberries can produce a red color in
acidic urine.

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ABNORMAL
URINE COLOR
Brown/Black
● may contain melanin or homogentisic acid
● Acid urine containing hemoglobin will darken on
standing because of the formation of
methemoglobin
● Cola colored urine = seen with rhabdomyolysis and
in some patients taking L-dopa (a precursor to
dopamine that passes the blood-brain barrier and
is mainly taken up by the dopaminergic neurons that
convert L-DOPA to dopamine and increase their
dopamine production and storage.)

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ABNORMAL
URINE COLOR
Brown/Black
● Homogentisic acid, a metabolite of phenylalanine,
imparts a black color to alkaline urine from persons
with the inborn-error of metabolism, called
alkaptonuria.
● Urine-containing homogentisic acid will darken more
rapidly when alkaline.
● Medications: levodopa, methyldopa, phenol
derivatives, and metronidazole.

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ABNORMAL
URINE COLOR
Blue/Green
POSSIBLE CAUSES:
● urinary tract infection by Pseudomonas species
● intestinal tract infections resulting in increased
urinary indican.
● Chlorophyll
● Ingestion of breath deodorizers (Clorets) can result
in a green urine color.
● Medication: methocarbamol (Robaxin), methylene
blue, and amitriptyline (Elavil) may cause blue urine.
● Phenol derivatives found in certain intravenous
medications produce green urine on oxidation

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CLARITY
● general term that refers to the transparency/turbidity of a urine specimen.
● REPORTING: clear, hazy, cloudy, turbid, and milky
NORMAL CLARITY:
● Freshly voided normal urine is usually clear, particularly if it is a midstream
clean-catch specimen
● Precipitation of amorphous phosphates and carbonates may cause a white
cloudiness
NON PATHOLOGIC CLARITY:
● presence of squamous epithelial cells and mucus, particularly in specimens
from women, can result in a hazy but normal urine.

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CLARITY

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CLARITY
HAZY
CLEAR CLOUDY TURBID
MILKY

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● Refrigerated specimens frequently develop a thick
turbidity caused by the precipitation of amorphous
phosphates, carbonates, and urates
● White precipitate = Amorphous phosphates and
carbonates (urine with an alkaline pH)
● Pink precipitate (pink brick dust) = amorphous urates
produce a precipitate in acidic urine; due to the
presence of uroerythrin.
ADDITIONAL NON PATHOLOGIC CAUSE:
➢ semen
➢ fecal contamination
➢ radiographic contrast media
➢ talcum powder
➢ vaginal cream

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PATHOLOGIC TURBIDITY:
● RBCs
● white blood cells (WBCs)
● bacteria caused by infection or a systemic organ
disorder.

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SPECIFIC GRAVITY
● reabsorption is often the first renal function to become
impaired.
● detects possible dehydration or abnormalities in
antidiuretic hormone
● Defined as: the density of a solution compared with
the density of a similar volume of distilled water at a
similar temperature.
● Performed in main two types:
a. direct methods
- urinometer (hydrometer)
- harmonic oscillation densitometry (HOD)
b. Indirect methods
- Refractometer
- chemical reagent strip.

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SPECIFIC GRAVITY
❖ URINOMETER
- consists of a weighted float attached to a scale that
has been calibrated in terms of urine specific gravity
- designed to sink to a level of 1.000 in distilled water.
- Urinometry is less accurate than the other methods
currently available and is not recommended by the
Clinical and Laboratory Standards Institute (CLSI)
formerly the National Committee for Clinical
Laboratory Standards (NCCLS).
Disadvantage: measure specific gravity is that it requires
a large volume (10 to 15 mL) of specimen.

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SPECIFIC GRAVITY
❖ URINOMETER
- also need to be corrected for temperature, inasmuch
as urinometers are calibrated to read 1.000 in distilled
water at a particular temperature.
- If the specimen is cold, 0.001 must be subtracted from
the reading for every 3℃ that the specimen
temperature is below the urinometer calibration
temperature.

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SPECIFIC GRAVITY
❖ REFRACTOMETER
- Measuring refractive index.
- Refractive index is a comparison of the velocity of light
in air with the velocity of light in a solution
- the specific gravity scale is calibrated in terms of the
angles at which light passes through the specimen
- ADVANTAGE: using a small volume of specimen (one
or two drops)
- Temperature is compensated between 15℃ and 38℃.
- Corrections for glucose and protein are still calculated,
although refractometer readings are less affected by
particle density than are urinometer readings.

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SPECIFIC GRAVITY
❖ REFRACTOMETER
- CALIBRATION: distilled water that should read 1.000.
❖ HARMONIC OSCILLATION DENSITOMETRY
- Principle: frequency of a sound wave entering a
solution changes in proportion to the density of the
solution.
- Results are linear up to a specific gravity of 1.080.

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SPECIFIC GRAVITY

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💡MUST KNOW:
➢ The specific gravity of the plasma filtrate entering the glomerulus is 1.010
Isosthenuric = urine with a specific gravity of 1.010
Hyposthenuric = Specimens below 1.010
Hypersthenuric = above 1.010
➢ Normal random specimens may range from 1.003 to 1.035, depending on
the patient’s amount of hydration
➢ Specimens measuring lower than 1.003 probably are not urine.

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ODOR
● Freshly voided urine has a faint aromatic odor.
● Lack of odor in urine from patients with acute renal
failure suggests acute tubular necrosis rather than
prerenal failure.
● Ammonia odor = The breakdown of urea

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ODOR
Amino Acid Disorder Urine Odor
Isovaleric acidemia and glutaric acidemia Sweaty feet
Maple syrup urine disease (MSUD) Maple syrup
Methionine malabsorption Cabbage, hops
Phenylketonuria Mousy
Trimethylaminuria Rotting fish
Tyrosinemia Rancid
Based on Henry’s 22nd Ed.

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