Water Diuresis and Urinalysis: Experiment and Results

This experiment aimed at determining the osmotic regulation of the kidneys and studying the physical characteristics of urine. The results show the impact of water and saline treatment on ECF volume and osmolality, and the comparison of physical characteristics and substances in normal and unknown urine samples.

Title
Student’s Name:
Student’s number:
Subject:
WATER DIURESIS AND URINALYSIS
Date of practical session

Aims
The experiment aimed at:
 Determining the osmotic regulation of the kidneys when it comes to maintaining a
balance of fluids in the body
 Studying the physical characteristics of urine and establishing if a urine sample is normal
Introduction
The human kidneys have a significant role to play in the human body as they aid in the
regulation of the volume of plasma, the osmolality, pH, ionic composition and even elimination
of waste products of metabolic processes. All these regulations work in harmony to ensure that
homeostasis is maintained in the body1. The main determinants of the composition of blood
include cellular metabolism, urinary output as well as the diet. To the tune of 180 liters of blood
plasma is filtered by the nephrons of the kidney in 24 hours through the glomeruli into the
tubules in which it undergoes selective processing by the tubular reabsorption and secretion.
The human body has up to 5 liters of blood circulating at any given time out of which twenty
percent which represents one liter of the blood circulates to the kidneys. The roles of the kidney
are the billions of the nephrons that they are composed of which serve to filter blood. Each of the
neurons of the kidney has renal corpuscle and renal tubules. In the renal corpuscles are the
Bowman’s capsule and glomerulus while in the renal tubules contains the loop of Henle,
proximal tubule, the distal convoluted tubules as well as the connecting tubules which connect
the collecting duct2.
There are two parts of the proximal tubule: proximal convoluted tubule and the proximal straight
tubule. The loop of Henle is subdivided into three main parts: a thin ascending limb, the
descending limb, and the thick ascending limb. The entry of blood is first through the afferent

arteriole then into the glomerulus and finally, it's filtered out to the Bowman's capsule. The
filtrate is referred to as the glomerular filtrate and is plasma that does not contain proteins.
Reabsorption and elimination of solutes, ions, and water take place in the kidneys. Whereas
reabsorption defines the movement of water, ions, and nutrients back to the blood through the
peritubular capillaries from the filtrate that is found in the tubules, a greater portion of it takes
place in the proximal convoluted tubule and some fraction in the distal convoluted tubule.
Three main hormones aid in the proper functioning of the kidneys: Anti-Diuretic Hormone,
Atrial Natriuretic Peptide, and Aldosterone3. Anti-Diuretic Hormone is termed as a
vasoconstrictor which raises the blood sugar levels and increases the reabsorption of water, urine
specific gravity, plasma volume as well as decreasing the flow rate of urine.
Stimulation of Anti-Diuretic Hormone targets the collecting duct and the proximal convoluted
tubule resulting into reabsorption of water. Aldosterone is generated in the adrenal cortex where
it stimulates Renin-Angiotensin-Aldosterone System upon a decrease in the volume, plasma
osmolality and pressure occurrence thereby resulting into a enhancement n the reabsorption of
sodium through the distal tubule4.
The role of this experimental study was to determine the kidneys' osmotic regulation when it
comes to maintaining a balance of fluids in the body as well as studying the various physical
characteristics of urine. Two subjects were chosen for the first study in which one consumed
fresh water and the other saline or salty water. The second part of the experiment involved
comparing the properties of urine from three different subjects against the normal characteristics
of urine.

Materials and Methods
Experimental Procedure for Part I
1. Every student was required to collect a morning sample of urine collected as soon as they
got out of bed and labeled it t=morning. Students selected as subject 1 or 2 not to pass
urine just before the experiment or take any caffeinated beverages.
Subject 1 would be undertaking the water test
Subject 2 would be undertaking the saline test.
2. Immediately upon arrival to the practical, Subject 1 and Subject 2 were required to
completely empty their bladder into the sterile collection container (graduated cylinder)
as soon as they arrive.
3. Record these measurements in the table below.
4. Subject 1 would drink 750 to 1000 ml of water quickly (within 5-10 minutes). Then
wait 15 minutes and collect a urine sample. Collect a further 2 urine samples at 15 minute
intervals over the next 45 minutes (i.e. t=15, t=30 and t=45). Ensure that the ‘recorder’
and subject are using the timer to keep an accurate measure of the timing5.
5. Subject 2 would drink 750 to 1000 ml of 0.9% (isotonic) saline quickly (within 5-10
minutes). Similar to the Subject 1, collect a urine sample at three 15 minute intervals over
the next 45 minutes (i.e. t=15, t=30 and t=45).
6. Wash down the area of the lab bench you are working on with a 70% ethanol solution.
Experimental Procedure for Part II
One strip was removed from bottle and cap replaced. Completely immerse reagent areas of the
strip in the sample and remove immediately.

1. In the process of elimination, the edge of the whole length of strip is run against the
container rim to eliminate the excess sample. The strip is held in a horizontal position so as to
avoid chances of mixing up of the chemicals from the nearby reagent areas and/or making the
hands dirty with the sample.
2. Compare reagent areas to the corresponding color chart you were given at the times
specified. Hold strip close to color blocks and match carefully. Avoid laying the stick directly
on the color chart.
3. Taking proper readings of the time is very important for results of higher accuracy. The
glucose and bilirubin test was read at 30 seconds upon dipping. The ketone test was read at 40
seconds; while that of the specific gravity done at 45 seconds; at 60 seconds the tests for
Urobilinogen, pH, nitrite, protein blood were conducted; and finally at 2 minutes the test for
leucocytes carried out6. The readings of the protein and pH areas may also be conducted
immediately or any time within 2 minutes after dipping. The pH area of the sample is checked
immediately upon dipping the strip. Should the colour on the pad be found to be non-uniform,
the readings on the reagent area are taken immediately and a comparison is made of the darkest
colour against the suitable colour chart. The readings of all the areas of the reagent may be taken
excluding that of the leucocytes for the purposes of identification of the negative specimens and
estimation of the specific gravity as well as the. A positive reaction on the leucocyte test even to
the least degree of significance at less than 2 minutes may be treated as a likely indication of the
presence of leucocytes in urine. Changes in colour take place after 2 minutes when there is no
diagnostic value12.

Results
10 20 30 40 50 60 70
0
2
4
6
8
10
12
14
16
Time (s)
Water flow rate (mL/min)
Figure 1: Graph for water flow rate versus time
As can be observed on the graph, the rate of flow of water decreased with an increase in the time
interval of collection of the water illustrating that the amount of the liquid that was leaving the
body kept decreasing with an increase in time.
0 2 4 6 8 10 12
0
2
4
6
8
10
12
Water Osmolarity (mOsm) Vs. Time (min)
Time
OSmolality
Figure 2: Graph for Water osmolality versus time

The graph indicates indirect proportionality such that as the time increased, the water osmolality
decreases to a level that it becomes fairly constant.
10 20 30 40 50 60 70
0
1
2
3
4
5
6
7
8
Time
Saline flow rate
Figure 3: Graph for Saline flow rate versus time
As can be observed on the graph, the saline flow rate decreased with an increase in the time
interval of collection of the water illustrating that the amount of saline that was leaving the body
kept decreasing with an increase in time.
0 2 4 6 8 10 12
0
2
4
6
8
10
12
Water Osmolarity (mOsm) Vs. Time (min)
Time (min)
Osmolality
Figure 4: Graph Saline osmolality versus time

The graph indicates indirect proportionality such that as the time increased, the saline osmolality
decreases to a level that it becomes fairly constant.
Part II
Urinalysis Results
Observation
Normal
Values
Normal Urine Unknown #1 Unknown #2 Unknown #3
Physical
Characteristics
Colour
Pale yellow Yellow:
pale medium dark
Other:
____________
Yellow:
pale medium dark
Other:
___very pale /
cloudy _________
Yellow:
pale medium
dark Other
____________
Yellow:
pale medium
dark Other
____________
Transparency
Clear Clear
slightly
cloudy
cloudy
Clear
slightly
cloudy
cloudy
Clear
slightly
cloudy
cloudy
Clear
slightly
cloudy
cloudy
Odour
Characteristic Describe: Describe: Describe: Describe:
Table 1: Physical characteristics of normal urine compared against the unknown samples.
The table illustrates the differences between the control sample urine and the unknown's samples
of urine with regard to the color, odour, and transparency. A lot of deviation is noticed in the
transparency in which the normal urine is clear while the unknown samples are cloudy.
Mutlistix®
Results
Normal Values Normal Unknown #1 Unknown #2 Unknown
#3
Glucose negative negative negative 500-20 negative
Bilirubin negative negative negative negative negative
Ketone negative negative negative negative negative
Specific
Gravity
1.001 – 1.035 1.015 1.02 1.015
1.02
Blood negative negative negative negative 80

pH 5 to 9
(abnormal and
normal range)
6 6 6 6
Protein negative negative 100 negative negative
Urobilinogen 0.2-1 U/dL
3.2–16 μmol/L
0.2/3.2 0.2/3.2 0.2/3.2 0.2/3.2
Nitrite negative negative negative negative negative
Leucocytes negative negative negative negative negative
Table 2: Various substances available in the control of urine samples and the unknown samples
The table shows the different substances found in the control urine sample and the unknown
sample including protein, pH, nitrite, leucocytes, and blood among others. The table depicts a
close similarity between the control sample and the unknown samples for most of the substances.
Discussion
Water Treatment
 The consumption of water had minor impacts on the ECF volume and ECF osmolality as
any free water that was added to the ECF quickly somatically equilibrates with the
available intercellular space which was a fluid compartment that is greater than the
extracellular compartment7
 The resulting change in the ECF osmolarity illustrated more water available in the body.
The hormone ADH was stimulated and more of it produced which targeted the collecting
duct and distal tubule resulting into reabsorption of water.
 ADH enhanced the reabsorption back of water into the circulating by binding to the
receptor cells in the collecting duct
 Treatment with water increased the flow of urine since the more excess supply of water
in the body some of which had to be eliminated to maintain the osmotic balance of the
body as well as the homeostasis

 A low ECF osmolality would mean less sodium concentration in the blood that would
stimulate the production of aldosterone to facilitate the uptake of sodium ions8
 Aldosterone increased the uptake or absorption of sodium ions in the distal convoluted
tubule
Saline Treatment
 The treatment with saline increased ECF volume and ECF osmolality as the saline
treatment increased the isoosmotic of the solution.
 The amount of ANP produced increased with the resulting change in the ECF volume to
counter or inhibit the reabsorption of sodium ions and enhance excretion of sodium.
 Treatment with saline reduced the flow of urine and urine osmolarity as it led to more
reabsorption of water to achieve an osmotic equilibrium of body9.
 ANP served to inhibit the reabsorption of sodium ions in the collecting ducts and the
distal tubule and foster excretion of sodium
Morning Sample
 The osmolarity of the morning sample was higher than the other sample collected from
subject 1 since before drinking water there was an osmotic balance of the solutes and
solvent
 The morning urine sample had equal concentration of ADH and Aldosterone due to an
isotonic concentration that was attained by the body throughout the night when there
were no intakes of water of further reabsorption of osmolytes10
Part II: Urinalysis
The urines of the unknowns were cloudy while those of the controls were clear. The cloudy
nature could be attributed to conditions that result in too many crystalline substances or protein

in the urine. Such conditions could be infections in any part of the urinary tract among them
urethra or bladder11.
Conclusion
The experiment achieved the aims which were to determine the osmotic regulation of the
kidneys when it comes to maintaining a balance of fluids in the body as well as studying the
various physical characteristics of urine. Various treatments lead to various changes in the ECF
volume and ECF osmolality in which an increase in osmolytes results in an increase in ECF
volume and ECF osmolarity. The cloudy color of urine is not normal and could be due to
infections in the urinary tract

References
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Appendix
Table for recording group results:
Table 3: Results for Water Treatment Subject
Subject 1
(water)
Morning t=0 t=15 t=30 t=45 t= 60
Specific Gravity 1.042 1.018 1.001 1.001 1.001 1.001
Volume (mL) NA 300 220 130 140 138
Flow rate
(mL/min)
NA NA 14.66 8.67 9.3 9.2
Osmolarity
(mOsm)
1607.848 670.792 7.044 7.044 7.044 7.044
Table 4: Results for Saline Treatment Subject
Subject 2
(saline)
Morning t=0 t=15 t=30 t=45 t= 60
Specific Gravity 1.022 1.008 1.006 1.001 NA NA
Volume (mL) NA 330 110 90 0 0
Flow rate
(mL/min)
NA NA 7.333333 6 NA 0
Osmolarity
(mOsm)
826.968 280.352 202.264 7.044 NA NA