Wednesday, February 20, 2013

Reducing the Risk of Calcium Oxalate Kidney Stones (Human Nutrition 02-20-13)



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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National Institute of Diabetes and 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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