Joseph Melanson
Human Nutrition
Prof. Ortiz
7 December 2012
Reducing
the Risk of Forming Calcium-Oxalate Kidney Stones through Making Healthier Choices
in the Diet.
“Urinary tract stones”,
or what is referred to in medical terms as urolithiasis,
has “been known to mankind since antiquity” (Barnela, Soni, Saboo, &
Bhansali, 2012, p. 1). According to Harvard Men’s Health Watch, (2012), the
problem of kidney stones has “even been “diagnosed” in Egyptian mummies that
date back some 7,000 years” (p. 1). Kidney stones, according to Barnela et al.,
(2012), are composed of “organic and inorganic crystals amalgamated with proteins”
that form in the urinary tract (p. 1). Of the four different types of kidney
stones that occur: calcium-based, struvite, uric acid, and cystine stones,
“calcium-based stones are by far the most common, with nearly 80% of stones
composed of calcium compounds” such as “calcium oxalate, and in rarer cases, “calcium
phosphate” (Barnela et al., 2012, p. 2). As the causes of these four types of
stones arise from different causes, the prevention of kidney stone formation “must
be tailored to the stone type” (Wells et al., 2012, p. 1). The causes of
calcium oxalate stones in particular, have been mostly traced to: eating
certain foods high in oxalate, a high sodium intake, dehydration, and “certain types
of eating disorders” (Rodman, Sosa, Seidman, and Jones, 2007, p. 4). These
findings clearly make the origins of calcium oxalate stones, as well as their
preventions, directly dependent upon one’s nutritional intake. The risk of the formation
of calcium oxalate kidney stones can be greatly reduced through making healthier,
more nutritious choices in one's diet.
The
problem of calcium oxalate kidney stones is becoming an ever more increasing problem
in our modern era. “Since World War II, the incidence of stone disease has been
increasing dramatically in the Western industrialized nations” (Rodman et al.,
2007, p. 5). Globally the lifetime risk for kidney stones is “estimated between
15% and 25%, and changes in diet and lifestyle may have contributed to
increased incidence in women and adolescents” (Wells et al., 2012, p. 1). Kidney
stones, Dawson (2012) has stated, “accounts for about 1% of hospital admissions
worldwide and is the reason for 80,000 emergency department visits per year in
the U.K.” (p. 468). “At present, kidney stones send almost three million
Americans to the doctor each year, including over 500,000 trips to emergency
rooms and between 5% and 10% of all active stone passers may require
hospitalization (Harvard, 2012, p. 1). According to Rosenfeld (1995), 500,000
people in the United States “rush to their doctors’ offices or to emergency rooms
in excruciating pain from kidney stones” (p. 10). In the United States alone,
“the prevalence of kidney stones increased from 3.2% in the mid-‘70’s to 5.2%
in the mid-‘90’s, and the rates are continuing to rise” (Harvard, 2012, p. 1). Urolithiasis
is “currently more prevalent in men than in women (13% vs. 7%, respectively)”,
and is “three to four times more likely to present in white than nonwhite
patients” (Wells et al., 2012, p. 2). “Most vulnerable are men; Eurasians;
anyone living in dry, hot climates, especially in the United States; people who
are physically inactive; athletes who fail to replace fluid lost in
perspiration after a workout; and persons with gout” (Rosenfeld, 1995, p. 288).
According to Harvard (2012), “more than one of every eight American men will
develop a kidney stone at some time during his life; the highest risk occurs between
the ages of 20 and 50, with a peak age at age 30” (p. 1). “Men with a family
history of stone disease are two-and-a-half times more likely to form stones
than men without stone-forming relatives” (Harvard, 2012, p. 1). According to
Barnela et al., (2012), calcium oxalate stones are “the most frequent type,
accounting for up to 80%” of kidney stones that form in human beings (p. 1).
Kidney stones are an increasing problem globally and calcium oxalate stones in
particular are by far the most frequently found in patients.
Calcium
oxalate stones originate as a result of the natural functioning of the kidney. The
kidneys are the major organs of the urinary system, which is comprised of “two
kidneys, two ureters, the bladder, two sphincter muscles, and the urethra” (NIDDKD,
2007, p. 2). “We are born with two kidneys that lie against the back of the
abdominal wall, just above the waist” (Rodman et al., 2007, p. 9). The kidneys
are “bean-shaped organs, each about the size of your fist, located near the
middle of your back, just below the rib cage, one on each side of the spine” (NIDDKD,
2007, p. 2). “Though they account for just 0.5 percent of the body’s total
weight, the kidney’s use up to 10 percent of the body’s oxygen supply,
indicating intense metabolic activity” (Sizer and Whitney, 2011, p. 92). The
kidneys have “two basic functions: cleaning out toxic substances from the
blood, and keeping the things your body does need in proper balance” (Rodman et
al., 2007, p.10). “Every day, your kidneys process about 200 quarts of blood to
sift about 2 quarts of waste products and extra water” (NIDDKD, 2007, p. 3). “Your
blood transports nutrients and oxygen to the cells of the body and carries away
waste materials which are then brought back to the kidney to be excreted”
(Rodman et al., 2007, p. 10). “The kidneys work by filtering the blood that
comes into each kidney, through a very efficient system of microscopic nephrons” which could be described as a
small tube (Rodman et al., 2007, p. 11). Each kidney has around one million nephrons
and they are responsible for much of the work of the kidney. The nephrons “eventually
join and lead into the collecting ducts that finally empty into the renal or
kidney pelvis”, or a basin-like structure (Rodman et al., 2007, p. 12). “By the
time the fluid in the nephrons has passed through the collecting ducts to reach
the kidney pelvis, it has become urine” (Rodman et al., 2007, p. 10). “Urine
accumulates in the collecting system of a kidney, which includes the pelvis and
calyces” which can be described as a
cup-like structure (Rodman et al., 2007, p. 11). “The kidney pelvis has smooth
muscle that periodically contracts and squeezes urine into the ureter” or the
tubes that connect the kidney to the bladder, and “additional muscular
contractions of the ureter propel the urine into the bladder” where is stored until
the bladder is relieved (Rodman et al., 2007, p. 11). Urine, according to
Rodman et al., (2007), is “composed of water, salt, small amounts of acid, and
a variety of waste products such as urea, oxalate, uric acid, potassium,
magnesium, creatinine, and other unwanted things (e.g., lead)” (p. 10). “Although
urine may look like a simple fluid”, Harvard (2012) has reported, “it’s actually
a complex liquid” that contains many chemicals and “many minerals” (p. 1).
“When blood coming to the kidney for filtration contains too much of any
substance, it crystallizes in the urine, forming sediment and sludge, which can
eventually end up as stones” (Rosenfeld, 1995, p. 289). The function of the
kidneys act as waste removal for the body, and kidney stones are likely to form
when there is a lack of fluids to decrease the accumulation of substances that make
their way to the urinary tract.
Of the four
main types of kidney stones, those composed of calcium oxalate are by far the most
common. “Kidney stones may be as small as a grain of sand or as large as a
pearl”, but sometimes they are “even as big as golf balls” (NKUDIC, 2007, p.
5). “Stones may be smooth or jagged”, according to NKUDIC (2007), and generally
“they are usually yellow or brown” (5). According to Barnela et al., (2012),
calcium oxalate stones are “the most frequent type, accounting for up to 80%”
of kidney stones that form in human beings (p. 2). The other three types of
kidney stones are uric acid, found in “8-10 %” of cases, with cysteine and
struvite stones found in the remaining cases (Barnela et al., 2012, p. 2). According
to Rosenfeld (1995), “struvite stones (15 percent) form in persons with chronic
urinary tract infections; uric acid stones (8 percent) occur in person’s with
gout; and cystine stones account for some 4 percent of cases” resulting from a
“congenital abnormality that interferes with the kidney’s ability to reabsorb
cystine, an amino acid” (p. 289). Calcium oxalate stones are the most
frequently seen type of kidney stone as it is generally caused by dietary
choices. Oxalate is a common substance found in many foods and drinks, like
fruits, nuts, vegetables, milk, and chocolate to name a few. When oxalate
builds up to high levels in the blood, it can aggregate with calcium in the
urine with the tendency to “precipitate the calcium” to form the “nidus, or
center, of a kidney stone” (Townsend and Cohen, 2009, p. 134). Calcium oxalate
stones are by far the most commonly encountered type of kidney stones, due to
the amount of oxalate found in our modern diet.
There are
several different means to medically treat calcium oxalate kidney stones. “Kidney
stones are not a true diagnosis; rather it suggests a broad variety of
underlying diseases” Barnela et al., 2012, p. 1). “Classically, a patient with
kidney stones presents with sudden onset of severe pain in either the right or
left flank” and the pain usually “radiates to the groin in the same direction
as the passage of the stone. (Townsend and Cohen, 2007, p. 128). Symptoms that are
typically associated with kidney stones are: “extreme pain in your back or side
that will not go away, blood in the urine, fevers and chills, vomiting, urine
that smells bad or looks cloudy”, and a “burning feeling when you urinate” (NIDDKD,
2007, p. 1). “Although most stones form in
the kidney, they don’t usually cause symptoms until they drop into the ureter, the thin muscular tube that
carries urine down the bladder” (NIDDKD, 2007, p. 1). When symptoms present
themselves, the doctor will typically use either an X-ray, an ultrasound, or a
CT scan to determine the size, location, number of stones, as well as any
obstructions of flow in the urinary tract. Often the doctor will provide a
means for the patient to collect urine in a container, and/or strain the urine
flow to catch any stones that may be passed. This allows the doctor to
determine which of the four types of stone the patient may have in order to
best treat that particular type of kidney stone. When the doctor determines
what kind of stone that is present within the patient, medical treatment can
range from various kinds of surgery like lithotripsy, tunnel surgery, ureteroscopy,
or through pharmaceutical drugs like thiazide diuretics or citrates. Lithotripsy
is a “procedure of crushing a stone in the urinary bladder or urethra by means
of a lithotripter, a device that passes shock waves through a water-filled tub
in which the patient sits” (Townsend and Cohen, 2009, p. 134). “The shock waves
break a large stone into small stones that will pass through your urinary
system with your urine” (NIDDKD, 2007, p. 6). “In tunnel surgery, the doctor
makes a small cut into the patient’s back and makes a narrow tunnel through the
skin to the stone inside the kidney”, and using “a special instrument that goes
through the tunnel, the doctor can find a stone and remove it” (NIDDKD, 2007,
p. 6). Ureteroscopy is the use of a slender instrument, called the ureteroscope
that is “inserted into the urethra – the short tube that carries urine out of
the bladder, then into the ureter” (NKUDIC, 2007, p. 7). A camera within the ureteroscope
allows the doctor to use a cage on the wire that is inserted within the patient
to grab the stone and pull it out, or the doctor may pulverize the stone “with
a device inserted through the ureteroscope” (NKUDIC, 2007, p. 7). Various
medications exist as well to lower or prevent the risk of calcium oxalate
stones from forming. Thiazide diuretics, generally one of the “first line
therapy in most patients with uncomplicated hypertension” have the added
benefit of lowering the amount of calcium passed in the urine, thus greatly
reducing the formation of stones containing calcium (Townsend and Cohen, 2009,
p. 134). This method is also the cheapest as thiazide diuretics generally cost
“about a penny a pill” (Townsend and Cohen, 2009, p. 134). According to Dawson
(2012), another common pharmaceutical treatment that is used by doctors in the treatment of calcium oxalate kidney
stones is known as citrate supplementation and is “a particularly effective
therapeutic intervention” (p. 1). Kidney stones, no matter the type, require that
the “management of stone disease needs individualization” for the best
treatment and prevention of their recurrence (Barnela et al., 2012, p. 6). Several
methods exist for the treatment of calcium oxalate stones, and the patient’s
doctor can choose the best method to treat this particular type of kidney
stone.
The risk of the
formation of calcium oxalate kidney stones can be easily prevented through changes
in one’s own diet and lifestyle habits. “Though the pathogenesis of stone disease
is not fully understood, systematic metabolic evaluation, medical treatment of
underlying conditions, and patient specific modification in diet and lifestyle
are effective in reducing the incidence and recurrence of stone disease” (Barnela
et al., 2012, p. 1). “After many years of trying to find a medicine that would
“cure” people of kidney stones, doctors found that two-thirds of patients seen
with recurring stones stopped making them with basic dietary advice” (Rodman et
al., 2007, p. 6). “Limiting sodium in the diet is important as increased sodium
intake is accompanied by increased absorption of calcium and increased
likelihood of stone recurrence in the case of calcium stones” (Townsend and
Cohen, 2009, p. 135). “A moderate calcium intake is recommended as research has
shown that limiting calcium in the diet may result in an increased chance of
developing osteoporosis, or weak bones”, and it does “not decrease your chance
of developing further calcium stones” (Townsend and Cohen, 2009, p. 135).
Calcium binds with oxalate in the diet and a certain amount can prevent them
“from being absorbed in the first place so it gets lost in the stool when you
have a bowel movement” rather than allowing it to make its way to the kidneys (Townsend
and Cohen, 2009, p. 132). Avoiding foods high in oxalate is an important factor
in preventing the formation of calcium oxalate kidney stones. The single most
important factor in reducing the formation of kidney stones though, no matter
the type, is an increased intake of fluids. According to NIDDK (2007), “you can
drink ginger ale, lemon-lime sodas, and fruit juices” but one should “limit
your coffee, tea, and cola to 1 or 2 cups a day because the caffeine may cause
you to lose fluid too quickly” (p. 9). Other fluids to avoid are grapefruit
juice, alcohol, and Gatorade “mostly because the sodium in it tends to increase
the urine calcium” (Townsend and Cohen, 2009, p. 135). The best fluid for one
to drink in order to prevent calcium oxalate stones in the urinary system is
water. “The key to preventing” the formation of calcium oxalate stones, according
to Rosenfeld (1995), is “to drink all the water you possibly can thus diluting
whatever substance may form stones and reducing the chances” of these
substances from “solidifying” (p. 296). According to Barnela et al., (2012),
“clinical presentation, proper history, and laboratory tests have shown that
increasing urine volume to at least 2 liters a day can reduce the recurrence of
stone disease by up to 40-50%” (p. 1). “So if you are prone to kidney stones
(and that’s virtually everyone), drink more water than you lose in perspiration,
sweat, urine, and stool – at least two quarts a day” (Rosenfeld, 1995, p. 297).
Townsend and Cohen (2009) have recommended an intake of “ten eight-ounce
glasses” of water a day”, or 2 glasses with “each meal”, “2 glasses in the late
afternoon, and 2 glasses at bedtime” (p. 136). The risk of forming calcium
oxalate kidney stones can be greatly reduced by simple changes in the diet such
as limiting one’s sodium intake, avoiding foods and drinks high in oxalate,
consuming a moderate amount of foods that contain calcium, and especially
through increasing one’s consumption of water to at least ten eight-ounce
glasses a day.
Kidney
stones, especially calcium oxalate stones, have been a problem to mankind for
at least several thousand years, and the incidence of their occurrence is
increasing all over the globe. Our modern era has only increased the prevalence
of calcium oxalate kidney stones due to the abundance of unhealthy foods and
drinks that are becoming increasingly easier for people to gain access to. The
natural functioning of the kidneys cause calcium oxalate stones to form when there
is an abundance of oxalate in the blood which eventually makes its way to the urinary
tract. Of the four types of kidney stones that are likely to occur, calcium
oxalate stones are by far the most commonly found in patients. There exists
several different medical techniques to treat the problem of calcium oxalate
kidney stones. The prevention of calcium oxalate kidney stones can be easily
reduced and prevented through making simple choices in one’s nutritional
intake, and especially through consuming enough water to prevent the substances
that form kidney stones from accumulating within the urinary tract in the first
place.
Works Cited:
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S., & Bhansali, A. S. (2012). “Medical Management of
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16, Issue
2. PDF.
Dawson, C.H., & Tomson, C.R.V.
(2012) “Kidney Stone Disease: Pathophysiology, Investigation, and Medical
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Stones: Common, Painful, Preventable.” Harvard Health Publications. Vol. 16.
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Digestive and Kidney Diseases (2007). What
I Need to Know about Kidney Stones. U.S. Department of Health and Human
Services. NIH Publication No. 07-4154. PDF. www.kidney.niddk.nih.gov
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Information Clearinghouse. (2007). Kidney
Stones: What You Need to Know. U.S. Department of Health and Human
Services. National Institute of Health. NIH Publication No. 08-6186. PDF. www.kidney.niddk.nih.gov.
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