Body fluid ( the Urine ) Urinalysis

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Body Fluids
♦ Aim :
This course aim to identify the importance of body fluids including urine,
blood, lymph, milk, semen, cerebrospinal fluid, and amniotic fluid.
I. FUNCTION:
• Vital to life; help maintain body temperature and cell shape; involved
in transporting nutrients, gases, and wastes; principle fluid in body is
water.
• Skin, lungs and kidneys work together to maintain the proper fluid
balance.
II. FLUID COMPARTMENTS:
• 2 main; separated by capillary walls & cell membranes:
A.intracellular fluid (ICF): within cells; 40% of body weight and 70% of
total body water
B.extracellular fluid (ECF): outside cells; 20% of total body weight and
30 % of total body water; comprised of:
♣ Extracellular fluid includes
- Interstitial fluid
- Present between the cells
- Approximately 80% of ECF
- Plasma
- Present in blood
- Approximately 20% of ECF

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• Also includes :
• Lymph
• synovial fluid
• cerebrospinal fluid
• endolymph,
• perilymph,
• pleural, pericardial and
peritoneal fluids
III. BODY WATER DISTRIBUTION & SPACING:
• A. Distribution varies with age, sex and body composition.
• Percentage of body weight that is water is about 80% in a full-term
infant, 60% in a typical lean, and 45-50% of obese and elderly.
• This puts infants, elderly, and obese individuals at greater risk for fluid
related problems.
• B. Fluid spacing is a term used to classify the distribution of water in
the body:
• 1. First Spacing: describes normal distribution of fluid in the body in
both the intracellular and extracellular fluid compartments.
• 2. Second Spacing: describes the excess accumulation of fluid in the
interstitial spaces, which we also call edema.
• 3. Third Spacing: occurs when fluid accumulates in areas that
normally have no fluid or minimal amount of fluid, such as with
ascites, and edema associated with burns.
• In extreme cases third spacing can cause a relative hypovolemia.

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• 4. Fluid Status: 1 liter of water weighs 2.2 pounds.
• A sudden weight gain or loss is the best indicator of fluid status.
• Patients that need to have their fluid status monitored should have not
only their Intake and Output measured, but also daily beside weights.
♦ Composition of body fluids:
• Organic substances • Inorganic substances
• Glucose
• Amino acids
• Fatty acids
• Hormones
• Enzymes
• Sodium
• Potassium
• Calcium
• Magnesium
• Chloride
• Phosphate
• Sulphate
♦ Sodium Na+
:
– Most abundant ion in ECF
– 90% of extracellular cations
– Plays pivotal role in fluid and electrolyte balance as it accounts
for half of the osmolarity of ECF

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♦ Chloride Cl-
:
– Most prevalent anion in ECF
– Moves easily between ECF and ICF because most plasma
membranes contain Cl- leakage channels and transporters
– Can help balance levels of anions in different fluids
♦ Bicarbonate HCO3
-
:
– Second most prevalent extracellular anion
– Concentration increases in blood passing through systemic
capillaries picking up carbon dioxide
– Chloride shift helps maintain correct balance of anions in ECF
and ICF
♦ Potassium K+
:
– Most abundant cation in ICF
– Establish resting membrane potential in neurons and muscle
fibers
– Maintains normal ICF fluid volume
– Helps regulate pH of body fluids when exchanged for H+
♦ Magnesium Mg2+
:
– Mg2+ in ICF (45%) or ECF (1%)
– Second most common intracellular cation
– Cofactor for certain enzymes and sodium-potassium pump
– Essential for synaptic transmission, normal neuromuscular
activity and myocardial function

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◘ Specialized Fluids of the Body :
• Urine
• Blood
• Lymph
• Milk
• Semen
• Amniotic Fluid
• Cerebrospinal Fluid
♠ Urine
• Urine is formed in the kidneys
• Is a product of ultrafiltration of plasma by the renal glomeruli which is a
network of arteriolar capillaries, each glomeruli is surrounded by
Bowman’s capsule (a double epithelial sac) like a rounded funnel which
leads to the tube.
☺ Purpose
• Urine contains important metabolic information
• General evaluation of health
• Diagnosis of disease or disorders of the kidneys or urinary tract
• Diagnosis of other systemic disease that affect kidney function
• Monitoring of patients with diabetes
• Screening for drug abuse (eg. Sulfonamide or aminoglycosides)

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◘ Collection of urine specimens
• The first voided morning urine (most concentrated) - qualitative
• Random urine (routine)
• 24hrs sample- quantitative
• Mid-stream clean catch (MSCC) (for urine culture)- UTI
• Post prandial sample-D.M
☺ Attention
• Need to be examined within 1 hour
• The urine sample must be collected in a clean, dry container and
should be examined when freshly voided.
• Red cells, leukocytes and casts decompose with time.
• Bilirubin and urobilinogen will decrease especially with exposure to
light.
• Glucose is utilized by bacteria and cells; ketones are utilized or
volatilized.
• Bacterial contamination usually occurs resulting in alkalization of the
urine owing to the conversion of urea to ammonia.
• Turbidity develops as bacteria multiply and alkaline precipitates.
• The colour will change (darkens)
• The odour becomes offensive.

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◘ Storage and preservation
• Random specimens for routine analysis should be examined fresh, within
one hour after voiding or refrigerated and examined as soon as possible.
• Freezing is used for aliquots of urine for quantitative chemical tests.
1-Formalin
• Cells and casts may be preserved by rinsing the empty container with
formalin prior to use but it interferes with tests for sugar.
2-Thymol
• One crystal of thymol per 10 to 15 ml will preserve sediments but
interferes with test for bile salts and bile pigments.
• Toluene and chloroform are usually not desirable, chloroform mixes with
the deposit.
3-Sodium fluoride
• Glucose in 24 hour urine collections is preserved by using sodium fluoride
(0.5 g) it may inhibit the reagent strip test for glucose.
• It does not inhibit the qualitative copper reduction tests (Benedict).
• Xylose in urine may be preserved with sodium fluoride.

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◘ Types of Analysis
1- Macroscopic Examination
Physical characteristics : color, odor, turbidity, volume, & specific
gravity
Chemical Analysis (Urine Dipstick) : pH, glucose, protein, ketones,
pus (WBC’s & bacteria), RBC’s, hemoglobin, bile
2- Microscopic Examination of urine sediment: crystals, cells, etc.
☺ Physical properties:

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1.Volume:
• The normal 24-hour urine volume of an adult is between 600-2000 ml.
• It varies greatly with the fluid intake (which is usually a matter of habit)
and on the loss of fluid by other routes (sweetening due to physical activity
and external temperature).
• The volume of urine is less in summer than in winter.
♦ Oliguria (<500 ml)
• deficient urine secretion develops in dehydration, urinary tract
obstruction, as well as non-renal disease due to deficient intake of water
and excessive loss of fluid by other routes, for example by hemorrhage,
vomiting and diarrhea.
♦ Anuria
• is the cessation of secretion of urine by the kidneys.
♦ Polyuria or diuresis
• excessive excretion of urine develops in diabetes inspidus, hysterical
polydipsia, increased salt intake, and high protein intake and in any disease
where there is an increased excretion of metabolites.
♦ Nocturia:
• increased flow of urine at night (an early symptom of kidney disease) over
500 ml of urine of specific gravity 1.018 passed at 12 hrs night period.
2. pH:
• On a normal mixed diet the urine is usually acid (~ 6).
• A vegetarian diet causes a tendency to alkalosis, thereby produces alkaline
urine, since the oxidation of food produces salts of inorganic acids as sodium
lactate and sodium iodate.

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• Urine pH decreases after a meal because of the increased secretion of HCl into
the stomach for digestion.
• When the protein intake is high, the urine is usually acid since the oxidation of
S-containing amino acids produces H2SO4 and H3PO4
.
• Alkaline urine occurs in renal diseases such as chronic glomerulonephritis
because of decreased glomerular filtration, which causes a diminished excretion
of phosphate, sulfate and other acid buffers.
• Urine pH decreases at the early morning or after any fairly prolonged period of
sleep because of the mild respiratory acidosis occurring with sleep and the renal
compensation to that acidosis.
• The normal urine becomes alkaline on standing because of the conversion of
urea to ammonia by bacterial action.
Acidic urine
• Ketosis-diabetes, starvation,
fever
• Systemic acidosis
• UTI- E.coli
• Acidification therapy
Alkaline urine
• Strict vegetarian
• Systemic alkalosis
• UTI- Proteus
• Alkalization therapy
3. Colour
• The colour of the urine is affected by many components
(concentration, food pigments, dyes, medication, and blood).
• The intensity of the colour of normal urine is dependent on the
concentration of the urine.
• The yellow or amber colour of normal urine is due to the presence of a
yellow pigment, urochrome.

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• Most changes in urine color are harmless and temporary and may be
due to:
• Certain foods – beets may turn urine red
• Dyes in foods/drinks
• Supplements – vitamins
• Prescription drugs
◘ Unusual urine colour can indicate an infection or serious illness
Examples of urine colour

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4. Appearance (Urine Clarity)
• Urine clarity refers to how clear the urine is.
• Terms used: clear, transparent, slightly cloudy, cloudy, or
turbid.
• “Normal” urine can be clear or cloudy.
• The clarity of the urine is not as important as the substance that
is causing the urine to be cloudy.
• The normal urine is usually clear or slightly turbid but it
becomes cloudy in alkaline and acidic urine due to the
precipitation of calcium phosphates (white) in the former and of
urates (pink colour) and oxalates in the latter.
• In pathological urine the cloudiness is due to the presence of
bacteria, pus or red blood cells (requires attention.).
◘ Substances that cause cloudiness but are not considered
unhealthy include:
– mucous,
– sperm and prostatic fluid,
– cells from the skin,
– normal urine crystals, and
– contaminants (like body lotions and powders).

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5. Smell or odour
• Normal fresh urine is usually aromatic due to the volatile fatty acids.
• On standing “Old” the decomposition of urea causes the odour to
become ammonical.
• Foul, offensive: Old specimen, pus or inflammation
• Sweet: Glucose
• Fruity: Ketones
6. Urine concentration (specific gravity):
Definition:
• The urine specific gravity can be defined as a comparison of the
weight of urine with the weight of an equal volume of distilled
water.
• It can also be defined as a measurement of density, which
depends not only on weight but also on the number of solute
particles in solution.
 Normal specific gravity: 1.015-1.025.
 It is highest in the first morning specimen.
 A low specific gravity may suggest kidney disease, the
damaged kidney tubules being unable efficiently to remove the
waste products of metabolism, such as urea from the blood.
These results in a less concentrated urine and raised blood urea.

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 A high specific gravity often suggests diabetes mellitus, a
disease in which there is an increase of sugar in the blood. This
passes into the urine, increasing its concentration.
- The specific gravity is increased if there is protein in the urine.