Urine and urinalysis

Urine and Urinalysis
By Prof. Liwayway Memije-Cruz

“It amazes me that organs that piss can
give human beings such perfect bliss. “-
Irving Layton’

Excretion
• Excretion is the process of throwing waste and harmful
substances from the body.
• The skin, lungs, kidneys and lower intestinal tract carry out
this function. The kidneys eliminate most of the excess
water and salt.
• Perspiration withdraws from the body about one-fourth
(1/4) of all the heat produced.
• When a person breathes, he eliminates carbon dioxide and
some water. An adult eliminates a volume of about 6 4/5
ounces (200ml) of carbon dioxide per minute. Many
different substances pass out of the body through the
kidneys.
• The body rids itself of waste products of digestion through
the colon or large intestine.

Kidneys
• The pair of organs that eliminate wastes from the body as urine
are known as kidneys.
• The human kidneys are located at the back wall of the abdominal
cavity, on either side of the spine below the diaphragm.
• Each brownish kidney is about 4.5 inches (11 centimeters) long,
2-3 inches (5-7.5) wide, and merely 1 inch (2.5cm) thick.
• Surrounding each kidney are two protective layers of tissue: a
thin, tough, inner layer of connective tissue, and a thicker outer
layer of fat. The kidneys produce urine continuously.
• Depending on the person’s diet, they produce from 20-48
ounces (0.6-1.4 l) of urine everyday. From each kidney, the urine
travels through a tube, the ureter, to the urinary bladder, where
it is stored. When the bladder is full, the urine is eliminated
through the urethra.

The tissue portion of the kidney
consists of two principal layers:
an outer layer is called the cortex
and an inner layer called
medulla. The tissue of the cortex
and most of the medulla is
composed of subunits called
nephrons. They are grouped into
about 10 large, compact, cone-
shaped clusters sharing common
blood supply and urine channels,
the pyramids. The urinary outlets
from each pyramid discharge
from the cone-shaped tip or
papilla, on the medullar surface
opposite the cortex. The papilla
protrudes into a sac, the renal
pelvis, which is located at the
edge of the kidney facing the
spine and an expansion of the
upper end of the ureter.

Urinary System
The urinary system
keeps everything in
balance by removing
waste, like urea, extra
salt, extra water and
other things the body
does not need..

The 3 Us of the Urinary System
• Ureters - slender tubes, each 25 to 30 cm (10 to 12
inches) long and 6 mm (1/4 inch) in diameter, and
serve as passageway to carry urine from the kidneys to
the bladder by peristalsis. They play an active role in
urine transport.
• Urinary Bladder - a muscular sac that stores urine. As it
fills, it’s muscular wall stretches. Micturition is
emptying of the urinary bladder. Incontinence is the
ability to control micturition.
• Urethra - is a muscular tube that leads urine from the
urinary bladder to body exterior. In males it is 20 cm
long and conducts both urine and sperm. In females, it
is 3-4 cm long and conducts only urine.

Urine Formation
Urine formation is summarized into filtration, reabsorption, and secretion.
1. Filtration takes place in the glomerulus. The glomeruli of the kidney are
mechanical filters. The walls of this structure are of such size that blood cells and
proteins cannot give but water, useful and dissolved substances that are very small to
pass through the pores. Thus, the fluid filtrate that passes out contains water, amino
acids, glucose and salts.
2. Reabsorption is the process in which substances are transported out of the
glomerular filtrate through the renal tubules and into the blood of the peritubular
capillary.
The process of tubular reabsorption is largely selective, using different modes of
transport on the different segments of the tubules. Reabsorption can be active that its
energy is expanded. It can also be passive when difference in concentration results in
the movement of the substance.
3. Secretion is the function of the nephrons, which involves that of secretion where
certain substances from the plasma peritubular capillary are transported into the
fluids of the renal tubules.

Secretion
• the amount of the particular substance that is excreted
in the urine maybe greater than the amount filtered
from the plasma in the glomerulus.
• substances are secreted by active transport mechanism
similar to those that function in reabsorption.
• secretion moves in opposite direction. For example,
some organic compounds like penicillin and histamine
are actively secreted in the tubular fluids. Hydrogen
ions and potassium are also actively secreted into the
tubular fluids.

Urine Composition
• Urine when freshly voided is generally clear and pale to
deep yellow. The normal yellow color is due to urochrome,
which is a pigment resulting from the body’s destruction of
hemoglobin. It is slightly acidic, but its pH value varies
widely. Nitrogenous wastes, water, and various ions such as
sodium and potassium are the substances normally present
in urine. Substances normally absent from the urine are
glucose, blood proteins, pus (WBC) and bile.
• The composition of urine that comes out of the collecting
tube varies from time to time and from person to person.
This is due to differences in food intake and physical activity.
The volume of urine produced by the kidneys varies from
about 0.6-0.5 liters per day. The exact volume is influenced
by temperature, air humidity, respiratory rate, body
temperature, and the person’s emotional conditions.

Urine
• body’s liquid waste,
mainly made of water,
salt, and chemicals
called urea and uric
acid.
• we eliminate daily
about 9 liters of urine,
made up of water and
certain solids.
• it contains the solid
urea, a waste product
of the used protein by
the body.

Volume
The normal range
for 24-hour urine
volume is 800 to
2000 milliliters
per day (with a
normal fluid
intake of about 2
liters per day).

Color
Normal urine color ranges
from pale yellow to deep
amber — the result of a
pigment called urochrome
and how diluted or
concentrated the urine is.
Pigments and other
compounds in certain foods
and medications can change
your urine color. Beets,
berries and fava beans are
among the foods most likely
to affect the color.

Odor
The odor of urine can vary somewhat,
in most cases, it does not have a strong
smell. It is faint aromatic.
With dehydration, the urine is more
concentrated and may have a stronger
ammonia scent than normal.

pH
 The glomerular filtrate
of blood is usually
acidified by the kidneys
from a pH of
approximately 7.4 to a
pH of about 6 in the
urine.
 Depending on the
person's acid-base status,
the pH of urine may
range from 4.5 to 8.

Specific Gravity
• It measures the ratio of
urine density compared
with water density and
provides information on
the kidney's ability to
concentrate urine.
• A urinary specific gravity
measurement is a routine
part of urinalysis.
• Normal range : 1.012 –
1.024 • Measured using
urinometer, refractometer,
dipsticks.

Chemical Constituents
Organic solutes
• urea, creatinine, uric
acid, and trace amounts
of enzymes,
carbohydrates,
hormones, fatty acids,
pigments, and mucins
Inorganic solutes
• sodium (Na+), potassium
(K+), chloride (Cl-),
magnesium (Mg2+),
calcium (Ca2+),
ammonium (NH4
+),
sulfates (SO4
2-), and
phosphates (e.g., PO4
3-).

NORMAL INORGANIC
CONSTITUENTS of URINE:

Calcium
Daily excretion – 200mg/day

Test for Calcium
Procedure: Mix 2ml of urine sample + 1%
acetic acid and 3 drops of 2% potassium
oxalate solution.
Observation : White precipitate of calcium
oxalate is formed
Inference : Calcium is precipitated as
calcium oxalate in acid medium.

Magnesium
• Magnesium is a mineral
that plays an important
role in many
biochemical reactions
including your
heartbeat, nerve and
muscle function, bone
development, energy
production, glucose and
blood pressure
regulation and protein
synthesis.
Deficient magnesium levels can lead
to:
• Muscle
cramps/spasms/tremors
• Fatigue/Somnolence
• Decreased reflexes
• Heart block
• Inexplicably low calcium
levels
• Nausea
• Loss of appetite
• Seizures
• Heart arrhythmia
• Diarrhea

Chloride
Normal chloride excreted in 24 hr urine sample is 8 –
15 g/ day(NaCl).

Test for Chloride
Procedure: To 2ml of urine sample add
HNO3 solution to acidify it; then add few
drops of AgNO3 solution.
Observation – Formation of curdy white
precipitate
Inference – Chloride is precipitated as AgCl
with Ag NO3 in presence of HNO3.

Sulfates
 Daily excretion : 1g/ day
 Sulfur is derived from catabolism of sulfur containing
amino acids.

Test for Sulfates
Procedure: Acidify 2ml of the urine sample
with several drops of HCl. Then add 10%
BaCl4 little by little.
Observation – White precipitate. Is formed.
Inference – Sulfate is precipitated as
barium sulfate with barium chloride.

Normal Organic Constituents of
Urine

Urea
• Daily excretion : 20-30 gm/day
• Urea is formed in the liver.
• End product of protein metabolism

Test for Urea
Procedure: Using a water bath, evaporate
10ml of the urine sample until its volume to
one third. Cool and add 2ml of 20% NaOH.
Shake the mixture and add 2 and 3 drops of
very dilute CuSO4.
Observation: Brisk effervescence
Inference : Hypobromite decomposes urea
to give nitrogen gas.

Uric Acid
 Daily excretion : 0.6-1gm/ day
 End product of purine metabolism.
 Increased levels of uric acid in urine is URICOSURIA

Test for Uric Acid
A uric acid test
measures the amount of
uric acid in the body.
Uric acid is a chemical
that's produced when
your body breaks down
purines. Purines are
compounds that enter
the bloodstream during
the natural breakdown
of cells in the body.

Test for Murexide
The murexide test is an
analytical technique to
identify the presence of
caffeine and other
purine derivatives in a
sample. These
compounds do not
respond to the common
alkaloid detecting tests
such as Dragendorff's
reagent.

Abnormal Constituents of Urine

Test for Coagulation
Heat 2ml or urine in a test tube at an angle
of 45°, boiling the upper half passing it
over the flame. If turbidity develops, it may
be due to protein or phosphate. Acidify
with 2 drops of 2% acetic acid. If turbidity
disappears, it is due to phosphates. If
protein is present, turbidity will not
disappear but will become more
flocculent.

Test for Heller’s
Place 1.0ml of concentrated HNO3 in a test
tube and by means of a pipette, add along
the side of the tube 2ml of urine. Take care
not to mix the contents. Observe the
formation of a white zone (white ring) of
precipitated protein at the junction of the
two liquids if protein is present.

Test for Glucose
To 2ml of Benedict’s solution. Add 3 drops
or urine and mix thoroughly and boil in
water bath for 3 minutes, cool. The amount
of precipitate and its color (green or red)
will depend on the quantity present in the
urine.

Test for Acetone Bodies
Treat 2ml of urine sample with few drops of
freshly prepared sodium nitroprusside
solution. Mix thoroughly and make alkaline
with NaOH. A ruby red color is produced if
acetone is present, Acidify with dilute acetic
acid. If acetone present, the red color is
intensified; if absent, it becomes yellow.

Test for Bile and Bile Pigments
Place 4ml of concentrated HNO3 in a test
tube. By means of a pipette, deliver down
the side of the tube 3ml of urine. Avoid
mixing. Colored ring will be formed (green
nearest the urine, blue, violet, red and
reddish yellow nearest the acid) if bile is
present.

Test for Bile Acids
Mix 3ml of urine and 3 drops of 5%
sucrose solution in test tube. Pour down
the side of the tube., 2 to 3ml of
concentrated H2SO4. A red rng is
observed at the point of contact to
indicate the presence of bile acids.

]
Sedimentary Constituents
Centrifuge about 20ml of urine for
several minutes. Discard the
supernatural fluid. Place a drop of
sediment on a dry slide and examine
under the LPO and HPO. Identify and
draw the sediments seen.

Determination of Solids in Urine
a. Get the weight of an empty pycnometer bottle (50ml).
Fill it with urine, wipe dry the surface and weigh again.
b. Discard the urine, wash the pycnometer fill it with
distilled water, again, weigh. (Note: normal urine spgr
1.025-1.030)
Get the specific gravity of urine using:
• The formula spgr= wt.pyc + urine –wt.pyc
• wt.pyc + dH2O –wt.pyc

What is Urinalysis?
 simply an analysis of the urine.
 a very common test that can be performed in many
health care settings, including doctors' offices,
urgent care facilities, laboratories, hospitals, and
even at home.
 performed by collecting a urine sample from the
patient in a specimen cup. Usually only small
amounts (30-60 mL) may be required for urinalysis
testing. The sample can be either analyzed in the
medical clinic or sent to a laboratory to perform the
tests. Urinalysis is abbreviated UA.

• in general, urinalysis is easily available and relatively
inexpensive.
• a simple test and can provide many useful information
about various diseases and conditions. Some physicians
refer to urinalysis as "a poor man's kidney biopsy"
because of the plethora of information that can be
obtained about the health of the kidney or other
internal diseases by this simple test.
• Urine can be evaluated by its physical appearance
(color, cloudiness, odor, clarity), also referred to as a
macroscopic analysis. It can be also analyzed based on
its chemical and molecular properties, including
microscopic assessment.

Reasons for taking urinalysis
• Routine medical evaluation: general yearly screening, assessment
before surgery (preoperative assessment), admission to hospital,
screening for kidney disease, diabetes mellitus, hypertension (high
blood pressure), liver disease, etc.
• Assessing particular symptoms: abdominal pain, painful urination,
flank pain, fever, blood in the urine, or other urinary symptoms.
• Diagnosing medical conditions: urinary tract infections, kidney
stones, uncontrolled diabetes (high blood sugars), kidney
impairment, muscle breakdown (rhabdomyolysis), protein in
urine, drug screening, and kidney inflammation
(glomerulonephritis).
• Monitoring disease progression and response to therapy: diabetes
related kidney disease, kidney impairment, lupus related kidney
disease, blood pressure related kidney disease, kidney infection,
protein in urine, blood in urine.
• Pregnancy testing

What does urinalysis involve?
 done by collecting a urine sample from a
patient.
 optimal sample tends to be an early morning
urine sample because it is frequently the
most concentrated urine produced in the
day.
 no fasting is required before the collection of
urine sample and routine medications can
be taken before the test, unless otherwise
instructed by the ordering physician.

Methods of collecting urine
• Urine is collected in a clean urine specimen cup while
the patient is urinating. It is best to avoid collecting the
initial stream of urine. After the initial part of urine is
disposed of in the toilet, then the urine is collected in
the urine container provided. Once about 30 mL to 60
mL (roughly 3 to 5 tablespoons) are collected in the
container for testing, the remainder of the urine may be
voided in the toilet again. This is called the midstream
clean catch urine collection.
• The collected urine sample should be taken to the
laboratory for analysis, typically within one hour of
collection. If transportation to the lab could take more
than one hour, then the sample may be refrigerated.

What is macroscopic urinalysis?
Macroscopic urinalysis is the direct visual observation of the urine,
noting its quantity, color, clarity or cloudiness,
Normal urine is typically light yellow and clear without any
cloudiness. Abnormalities in the color, clarity, and cloudiness may
suggest possibility of
 an infection (cloudy urine),
 dehydration (dark urine color),
 liver disease ("bilirubin," a digestive substance secreted by the
liver, stains urine a tea or cola color),
 blood in the urine (visible to the eye may indicate urinary tract
infection, stones, tumors, or injuries), or
 breakdown of muscle (orange- or tea-colored urine).
 Very foamy urine may represent large amounts of protein in the
urine (proteinuria).

What is urine dipstick chemical analysis?
• a narrow plastic strip which has several squares of different
colors attached to it. Each small square represents a
component of the test used to interpret urinalysis. The entire
test strip is dipped in the urine sample and color changes in
each square are noted. The color change takes place after
several seconds to a few minutes from dipping the strip. If
read too early or too long after the urinalysis strip is dipped,
the results may not be accurate.
• Each color change on a particular square may indicate
specific abnormalities in the urine sample caused by a
certain chemical reaction. The reference for color changes is
posted on the plastic bottle container of the urine test strips.
This makes for easy and quick interpretation of the
urinalysis results by placing the strip next to the container
and comparing its color changes to the reference provided.

The squares on the dipstick represent the following
components in the urine:
• Specific gravity (concentration of urine)
• Acidity of the urine (pH)
• Protein in the urine (mainly albumin)
• Glucose in the urine (sugar)
• Ketones (products of fat metabolism)
• Hemoglobin/blood in the urine
• Leukocyte esterase (suggestive of white blood cells in urine)
• Nitrite (suggestive of bacteria in urine)
• Bilirubin (possible liver disease or red blood cell breakdown)
• Urobilinogen (possible liver disease or etodolac [Lodine]
medication)

References
• https://www.cincinnatichildrens.org/health/u/urinary-system
• https://www.webmd.com/urinary-incontinence-oab/truth-about-urine#1
• https://www.thoughtco.com/the-chemical-composition-of-urine-603883
• http://learnanatomyphysiology.blogspot.com/2016/04/inorganic-constituents-in-
urine.html
• https://www.medicinenet.com/urinalysis/article.htm#what_is_urine_dipstick_chemic
al_analysis
• https://www.healthlabs.com/magnesium-testing-urine
• https://www.dreamstime.com/stock-photos-urine-test-medical-checkup-
image22428063
• https://www.slideshare.net/janicedesa/normal-constituents-of-urine
• http://fac.ksu.edu.sa/sites/default/files/physical_properties_and_detection_of_normal_
constituents_of_urine_lab_1_0.pdf

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