19.5: DISORDERS OF THE URINARY SYSTEM
 AWARENESS RIBBON
Awareness ribbons are symbols meant to show support or raise
consciousness for a cause. Different colors are associated with
different issues, often relating to health problems. The first ribbon to
gain familiarity for a health issue was the red ribbon for HIV/AIDS,
created in 1991. The pink ribbon for breast cancer awareness is
probably the best known today. Do you know what a green ribbon
like the one pictured in Figure 19.5.1 represents? Among several
other health problems, a green ribbon is meant to show support or
raise awareness for kidney disorders.
Figure 19.5.2 : Diabetic nephropathy is characterized by damage to the
capillaries in the glomeruli of the kidneys, represented by the lower of the
two inset diagrams.
POLYCYSTIC KIDNEY DISEASE
Figure 19.5.1 : Kidney disorder awareness ribbon
The kidneys play such vital roles in eliminating wastes and toxins and
maintaining body-wide homeostasis that disorders of the kidneys may be
life-threatening. The gradual loss of normal kidney function commonly
occurs with a number of disorders, including diabetes mellitus and high
blood pressure. Other disorders of the kidneys are caused by faulty genes
that are inherited. Loss of kidney function may eventually progress to
kidney failure.
Polycystic kidney disease (PKD) is a genetic disorder in which multiple
abnormal cysts develop and grow in the kidneys. Figure 19.5.3 shows a
pair of kidneys that are riddled with cysts from PKD. In people who
inherit PKD, the cysts may start to form at any point in life from infancy
through adulthood. Typically, both kidneys are affected. Symptoms of the
disorder may include high blood pressure, headaches, abdominal pain,
blood in the urine, and excessive urination.
DIABETIC NEPHROPATHY
Diabetic nephropathy is a progressive kidney disease caused by damage
to the capillaries in the glomeruli of the kidneys due to long-standing
diabetes mellitus (see Figure 19.5.2). It is not fully understood how
diabetes leads to damage of glomerular capillaries, but it is thought that
high levels of glucose in the blood are involved. In people with diabetes,
nephropathy is more likely if their blood glucose is poorly controlled.
Having high blood pressure, a history of cigarette smoking and a family
history of kidney problems are additional risk factors. Diabetic
nephropathy often has no symptoms at first. In fact, it may take up to a
decade after kidney damage begins for symptoms to appear. When they
do appear, they typically include severe tiredness, headaches, nausea,
frequent urination, and itchy skin.
Proteins are large molecules that usually are not filtered out of blood in
the glomeruli. When the glomerular capillaries are damaged, it allows
proteins such as albumin to leak into the filtrate from the blood. As a
result, albumin ends up being excreted in the urine. Finding a high level
of albumin in the urine is one indicator of diabetic nephropathy and helps
to diagnose the disorder. Drugs may be prescribed to reduce protein levels
in the urine. Controlling high blood sugar levels and hypertension (high
blood pressure) is also important to help slow kidney damage, as is a
reduction of sodium intake.
Figure 19.5.3 : In polycystic kidney disease, the kidneys are injured by the
formation of multiple cysts, which may grow to be quite large.
There are two types of PKD. The more common type is caused by an
autosomal dominant allele, and the less common type is caused by an
autosomal recessive allele. Both types collectively make PKD one of the
most common hereditary diseases in the United States, affecting more
than half a million people. There is little or no difference in the rate of
occurrence of PKD between genders or ethnic groups. There is no known
cure for this disease other than a kidney transplant.
KIDNEY FAILURE
Both diabetic nephropathy and PKD may lead to kidney (or renal) failure
(classified as end-stage kidney disease), in which the kidneys are no
longer able to adequately filter metabolic wastes from the blood. Longterm, uncontrolled high blood pressure is another common cause of
kidney failure. Symptoms of kidney failure may include nausea, more or
less frequent urination, blood in the urine, muscle cramps, anemia,
swelling of the extremities, and shortness of breath due to the
accumulation of fluid in the lungs. If kidney function drops below the
level needed to sustain life, then the only treatment option is kidney
transplantation or some means of artificial filtration of the blood, such as
by hemodialysis.
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Hemodialysis is a medical procedure in which blood is filtered externally
through a machine. You can see how it works in the simplified diagram in
Figure 19.5.4. During dialysis, waste products such as urea as well as
excess water are removed from the patient’s blood before the blood is
returned to the patient. Hemodialysis is typically done on an outpatient
basis in a hospital or special dialysis clinic. Less frequently, it is done in
the patient’s home. Depending on the patient’s size, among other factors,
the blood is filtered for 3 to 4 hours about 3 times a week. Because the
treatment is needed so frequently, hemodialysis is one of the most
common procedures performed in U.S. hospitals.
Figure 19.5.5 : Kidney stones form in the kidney and may grow large
enough to block the major calyx or ureter.
OTHER URINARY SYSTEM DISORDERS
Although disorders of the kidneys are generally the most serious urinary
system disorders, problems that affect other organs of the urinary tract are
generally more common. They include bladder infections and urinary
incontinence.
BLADDER INFECTION
A bladder infection, also called cystitis, is a very common type of
urinary tract infection in which the urinary bladder becomes infected by
bacteria (typically Escherichia coli), rarely by fungi. Symptoms of
bladder infections may include pain with urination, frequent urination,
KIDNEY STONES
and feeling the need to urinate despite having an empty bladder. In some
A kidney stone, also known as a renal calculus, is a solid crystal that
cases, there may be blood in the urine. A much less common type of
forms in a kidney from minerals in urine (see Figure 19.5.5). The
urinary tract infection is pyelonephritis, in which the kidney becomes
majority of kidney stones consist of crystals of calcium salts. Kidney
infected. If a kidney infection occurs, it is generally because of an
stones typically leave the body in the urine stream. A small stone may
untreated bladder infection. Bladder infections are treated mainly with
pass through the ureters and other urinary tract organs without causing
antibiotics.
symptoms and go undetected. A larger stone may cause pain when it
passes through the urinary tract. If a kidney stone grows large enough, it
may block the ureter. Blockage of a ureter may cause a decrease in kidney
function and damage to the kidney.
Figure 19.5.4 : This simple diagram shows the general process by which
blood is filtered externally in the process of hemodialysis. Blood is taken
from a patient, run through a filtration machine, and then returned.
A kidney stone that causes pain is generally treated with pain medication
until it passes through the urinary tract. A stone that causes a blockage
may be treated with lithotripsy. This is a medical procedure in which
high-intensity ultrasound pulses are applied externally to cause
fragmentation of the stone into pieces small enough to pass easily through
the urinary tract. Although lithotripsy is noninvasive, it can cause damage
to the kidneys. An alternative treatment for a stone that blocks urine flow
is to insert a stent into the ureter to expand it and allow both urine and the
stone to pass. In some cases, surgery may be required to physically
remove a large stone from the ureter.
A combination of lifestyle and genetic factors seem to predispose certain
Figure 19.5.6 : Using a diaphragm like this one as a barrier method of
people to develop kidney stones. Risk factors include high consumption
birth control may increase the risk of a woman developing a bladder
infection following sexual intercourse
of cola soft drinks, eating a diet high in animal protein, being overweight,
and not drinking enough fluids. Preventive measures are obvious. They Risk factors for urinary bladder infections include sexual intercourse
include limiting cola consumption, eating less animal protein, losing (especially when spermicide or a diaphragm, as shown in Figure 19.5.6,
weight, and increasing fluid intake.
is used for contraception), diabetes, obesity, and most importantly, female
sex. Bladder infections are four times more common in women than in
men. In fact, in women, they are the most common type of bacterial
infection, and as many as 1 in 10 women has a bladder infection in any
given year. Female anatomy explains the sex difference in the incidence
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of bladder infections. The urethra is much shorter and closer to the anus
in females than in males, so contamination of the urethra and then the
bladder with GI tract bacteria is more likely in females than in males.
Once the bacteria reach the bladder, they can attach to the bladder wall
and form a biofilm that resists the body’s immune response.
URINARY INCONTINENCE
Urinary incontinence is a chronic problem of uncontrolled leakage of
urine. It is very common, especially at older ages and especially in
women. Sometimes urinary incontinence is a sign of another health
problem, such as diabetes or obesity. Regardless of the underlying cause,
the symptoms of urinary incontinence alone may have a large impact on
the quality of life, frequently causing inconvenience, embarrassment, and
distress.
In a person with male anatomy, urinary incontinence is most commonly
caused by an enlarged prostate gland or treatment for prostate cancer. In
genetically female individuals, there are two common types of urinary
incontinence with different causes: stress incontinence and urge
incontinence.
Stress urinary incontinence is caused by loss of support of the urethra,
usually due to stretching of pelvic floor muscles during childbirth. It is
characterized by leakage of small amounts of urine with activities that
increase abdominal pressure, such as coughing, sneezing, or lifting.
Treatment of stress urinary incontinence may include Kegel exercises
to strengthen the pelvic muscles (see Explore More below). More
serious cases may call for surgery to improve support for the bladder.
Urge urinary incontinence (commonly called “overactive bladder”) is
caused by uncontrolled contractions of the detrusor muscle in the wall
of the bladder. This causes the bladder to empty unexpectedly. Urge
incontinence is characterized by leakage of large amounts of urine in
association with an insufficient warning to get to the bathroom in time.
Treatment of urge incontinence may include taking medication to
relax the detrusor muscle.
 FEATURE: MY HUMAN BODY
You probably have had to “donate” a urine specimen for analysis in
conjunction with a medical visit. A thorough medical exam often
includes clinical tests for urine. Understanding what your urine may
reveal about your health may help you appreciate the need for such
tests.
The most common urine test is called a urinalysis. In a routine
urinalysis, a urine sample may be analyzed by sight and smell and
with simple urine test strips. If a particular disorder is suspected,
urinalysis may be more extensive. For example, the urine may be
analyzed with specific tests or viewed under a microscope to identify
abnormal substances in the urine. If a bacterial infection is suspected,
a sample of urine may be cultured in the lab to see if it grows
bacteria and which type of bacteria grow. Knowing the type of
bacteria is important for deciding which class of antibiotics is likely
to be most effective in treating the infection.
The color and clarity of urine may be obvious first indicators of
disorders or other abnormalities. Normal urine is yellow to amber in
color and looks clear. If urine is nearly colorless, it could be a sign of
excessive fluid intake, or it might be a sign of diabetes. Very dark
urine may indicate dehydration, but it could also be caused by taking
certain medications or ingesting some other substances. If the urine
has a reddish tinge, it is often a sign of blood in the urine, which
could be due to a urinary tract infection, kidney stone, or even
cancer. If the urine appears cloudy instead of clear, it could be due to
white blood cells in the urine, which may be another sign of a
urinary tract infection.
Normal urine may have virtually no odor if it is very dilute. It will
have a stronger odor if it is concentrated. Brief changes in the normal
odor of urine often occur due to the ingestion of certain foods or
medications. For example, after eating asparagus, urine may have a
peculiar and distinctive odor for several hours. More significant is
urine that has a sweet smell, because this may indicate sugar in the
urine, which is a sign of diabetes.
Urine test strips, much like the familiar litmus test strips used to
detect acids and bases in a chemistry lab, are used to identify
abnormal levels of certain components in the urine. For example,
urine test strips can detect and quantify the presence of nitrites in
urine, which is usually a sign of infection with certain types of
bacteria. Urine test strips can also be used to identify proteins such
as albumin in urine, which may be a sign of a kidney infection or of
kidney failure. Levels of sodium in urine can also be measured with
test strips, and higher-than-normal levels may be another indication
of kidney failure. In addition, test strips can identify and quantify the
presence of white blood cells and blood in a urine specimen, both of
which are likely to be a sign of a urinary tract infection or some other
urinary system disorder.
Besides the use of urine test strips, other simple urine tests that are
often performed include Benedict’s test, which is a test for the
presence and quantity of glucose in urine. If the level is high, it is
likely to indicate diabetes. The test is so simple that it may even be
done in the home by the patient to monitor how well sugar levels are
being controlled. Testing for some other substances in urine requires
the patient to collect urine over a 24-hour period. This is the case, for
example, when testing for the adrenal hormone cortisol in urine.
When urine cortisol levels are higher than normal it may indicate
Cushing’s syndrome, and when the levels are lower than normal it
may indicate Addison’s disease.
REVIEW
1. What is diabetic nephropathy and what causes it?
2. Describe polycystic kidney disease (PKD).
3. Define kidney failure.
4. What are potential treatments for kidney failure when kidney function
drops below the level needed to sustain life?
5. Describe hemodialysis.
6. What are kidney stones?
7. How may a large kidney stone be removed from the body?
8. How are bladder infections usually treated?
9. Why are bladder infections much more common in females than in
males?
10. Define urinary incontinence.
11. Compare and contrast stress incontinence and urge incontinence.
12. Why is the presence of a protein such as albumin in the urine a cause
for concern?
13. Patients undergoing hemodialysis usually have to do this procedure a
few times a week. Why does it have to be done so frequently?
14. Which of the following is considered a genetic disorder?
19.5.3
A. Polycystic kidney disease
B. Diabetic nephropathy
C. Kidney failure
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D. Urinary incontinence
15. What is the most common cause of a kidney infection?
EXPLORE MORE
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ATTRIBUTIONS
1. Ribbon by rosanegra_1, Pixabay license
2. Diabetic Nephropathy by Blausen.com staff (2014). "Medical gallery
of Blausen Medical 2014". WikiJournal of Medicine 1 (2).
DOI:10.15347/wjm/2014.010. ISSN 2002-4436. CC BY 3.0 via
Wikimedia Commons
3. Polycystic kidneys by CDC/ Dr. Edwin P. Ewing, Jr., Public Domain,
via Wikimedia Commons
4. Hemodialysis by Blausen.com staff (2014). "Medical gallery of
Blausen Medical 2014". WikiJournal of Medicine 1 (2).
DOI:10.15347/wjm/2014.010. ISSN 2002-4436. CC BY 3.0 via
Wikimedia Commons
5. Kidney Stones by Blausen.com staff (2014). "Medical gallery of
Blausen Medical 2014". WikiJournal of Medicine 1 (2).
DOI:10.15347/wjm/2014.010. ISSN 2002-4436. CC BY 3.0 via
Wikimedia Commons
6. 'Durex' diaphragm by Wellcome Collection gallery (2018-03-21) CCBY-4.0 ia Wikimedia Commons
7. Text adapted from Human Biology by CK-12 licensed CC BY-NC 3.0
This page titled 19.5: Disorders of the Urinary System is shared under a CK-12
license and was authored, remixed, and/or curated by Suzanne Wakim & Mandeep
Grewal via source content that was edited to the style and standards of the
LibreTexts platform; a detailed edit history is available upon request.
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