Renal Calculi: Causes, Effects On the Kidneys and Treatments.
BSHU2 HUMAN PHYSIOLOGY 2
DEREK THOMSON DR I.C. WILKIE
WORD COUNT: 2809
RENAL CALCULI: CAUSES, EFFECTS ON THE KIDNEYS AND TREATMENTS.
INTRODUCTION: PAGE 4
OVERVIEW OF THE KIDNEY: PAGE 5
WHAT ARE THE KIDNEYS?
HOW DOES THE URINARY SYSTEM WORK?
CAUSES OF KIDNEY STONES: PAGE 7
WHAT ARE KIDNEY STONES?
WHAT CAUSES KIDNEY STONES TO FORM?
WHO GETS KIDNEY STONES?
WHAT ARE THE SYPTOMS?
HOW ARE THEY DIAGNOSED?
WHAT DIFFERENT TYPES ARE THERE?
EFFECTS ON THE KIDNEYS: PAGE 15
TREATMENTS: PAGE 17
RESEARCH ON STONES
CONCLUSIONS: PAGE 23
REFERENCES: PAGE 24
THIS ASSIGNMENT IS MY OWN WORK. IT HAS NOT BEEN, AND WILL NOT BE, PRESENTED FOR ASSESSMENT FOR ANY OTHER MODULE OR PIECE OF WORK WHICH ACCRUES CREDIT FOR THE AWARD FOR WHICH I AM CURRENTLY STUDYING OR FOR ANY OTHER AWARD.
Fortunately, most of us will never endure the pain of having a kidney stone, but it it’s the most common disorder of the urinary tract. 10% of the western public will have a kidney stone, or renal calculi as it’s sometimes known, at one time in there lives. But if you are thinking that these are products of the modern lifestyle, then think again. Scientists have found evidence of renal calculi in an Egyptian mummy which was thought to be approximately 7000 years old.
For sufferers of nephrolithiasis, or Renal Stone Disease, the pain can be unbearable, but most stones pass through the urinary system without needing a physician’s intervention. Some stones which cause other complications or lasting symptoms can be treated by various techniques, most of which, do not involve any surgery. And research provides us constantly with a better understanding of the many factors which promote stone formation.
2. OVERVIEW OF THE KIDNEY AND URINARY TRACT:
2.1 WHAT ARE THE KIDNEYS?
The kidneys are the master chemists of the human body. In a normal body, there are two kidneys, one under each side of the spine under the lower ribs. They are reddish brown in color, are about the size of a clenched fist and are shaped like kidney beans. The kidneys remove extra water and wastes from the blood, converting it to urine. They also help stabilize salt concentration and other chemicals in the blood. Hormones that build strong bones and promote red blood cell formation are produced in the kidneys.
2.2 HOW DOES THE URINARY SYSTEM WORK?
The urinary tract, or system, consists of the two kidneys, the ureters, the bladder and the urethra. Narrow tubes called ureters carry the waste from the blood, down to the bladder, which is a triangle-shaped chamber in the lower abdomen. The bladder is somewhat like a balloon. It has elastic walls which expand when filled with urine, and then these walls flatten together when the urine is passed out the body, through the urethra.
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FIGURE 1 SHOWS THE KIDNEYS AS PART OF THE URINARY SYSTEM.
3. CAUSES OF KIDNEY STONES:
3.1 WHAT ARE KIDNEY STONES?
Kidney stones are a mass of crystallized chemicals, which build up in the kidney. These masses can range from the size of a grain of sand, to the equivalent of a golf ball. Some stones stay in the kidney and produce no symptoms. Other stones can break away and travel down the urinary tract. If the stone is small enough, it can be passed out the body with very little resistance. But sometimes the stones are large enough to get lodged in the ureter, the bladder or urethra, which can cause intense pain. These can block the flow of urine or irritate the lining of the vessels.
FIGURE 2 SHOWS STONES IN THE KIDNEY, URETER AND BLADDER.
3.2 WHAT CAUSES KIDNEY STONES TO FORM?
What causes kidney stones to form is a slight taboo in the world of medicine. There is a great debate as to what actually contributes to the process. A person who has a family history of renal calculi is at greater risk. It is known what the crystals actually are, but there is no straight answer as to what exactly directly stimulates the accumulation of the chemicals. Normally, urine contains chemicals which inhibit this process from taking place, but these inhibitors do not always work. These substances include Urine glycoprotein, citrate, and pyrophosphates. Nephrocalcin is a glycoprotein inhibitor of calcium oxalate crystal growth that is present in normal urine. Some people are just more prone to developing these stones than others. There are several factors which are thought to contribute to nephrolithiasis:-
- Recurrent urinary tract infections.
- Drinking too little fluid.
- Blockage of the urinary tract.
- Limited activity for several weeks or more.
- Consuming too much calcium oxalate or uric acid in your diet.
- Consuming too much vitamin C or vitamin D.
- Certain medications.
- Certain metabolic diseases.
- Persistent kidney infection.
It is also known that 70% of people with the rare hereditary disease called Renal Tubular Acidosis develop kidney stones. Cystinuria is also a rare hereditary disease which increases the chance of stones. In this disease, too much of the Amino Acid Cystine, which does not dissolve in urine, is voided. This can lead to stones forming and Cystine being the main constituent.
3.3 WHO GETS KIDNEY STONES?
There is also some debate over who exactly is susceptible to this affliction, but there are no direct answers. Research has given indications as to who is more likely to suffer this ailment. Over the past 20 years, the number of kidney stone victims has been steadily increasing. Caucasians are more at risk than people of African descent. Men have a greater chance of development than women. And age is also an issue. If you are between 20 and 40, your chance of Nephrolithiasis is increased. A hot climate can also increase chance. Recent research has found that, people of Mediterranean ancestries, especially those of Portuguese extraction, are far more at risk of Uric Acid stones.
3.4 WHAT ARE THE SYPTOMS OF KIDNEY STONES?
Severe pain is usually the first indication that all is not well. This pain can be in the small of the back, under the ribs, or in the lower abdomen. This pain may then move down to the groin. This pain is caused by the blockage of the urine or irritation of the tubule lining. The pain may last for seconds, minutes or hours, and the pain is sharp. Nausea and vomiting may occur also. This intense pain will be followed by periods of relief. If the stone is too large to pass easily, pain will continue as the muscles in the wall of the tiny ureter try to squeeze the stone down into the bladder. This may result in blood being present in the urine. As the stone moves closer to the bladder, the person may feel the need to pass urine more often, or feel a deep burning sensation when urinating. If an infection is present, this may be accompanied by foul-smelling or cloudy urine, and fever or chills.
3.5 HOW ARE KIDNEY STONES DIAGNOSED?
Diagnosis for renal calculi is sometimes made when the patient goes to the doctor for a general health exam, and can be visually established by use of an x-ray or sonogram, usually when someone is complaining of blood in the urine or discomfort in the urinary tract or abdomen. Even “silent” stones, which are small enough to usually pass out the body without notice, can be picked up and located in the x-ray. Some stones, which are hard to pick up on the x-ray, can be more clearly seen by use of dye injections or an ultrasound. The stone’s image give the doctor valuable information, like the size, shape and location. The physician then may ask the patient about his/her past kidney illnesses, diet, family background and use of medications. Blood and urine tests help establish any abnormal chemicals, which may induce stone formation. A special x-ray of the urinary tract, called an I.V.P, or Intravenous Pyelogram, may also be used to establish the best treatment.
3.6 WHAT DIFFERENT TYPES OF KIDNEY STONES ARE THERE?
Different chemical imbalances in the urine produce stones with
different chemical compositions and shapes. The four most common types of stones are made of , , , and .
FIGURE 3 SHOWS A STONE OF CALCIUM OXALATE (97% MONOHYDRATE, 3% PROTEIN AND BLOOD)
FIGURE 4 SHOWS A STONE OF CALCIUM OXALATE (58% DIHYDRATE)
FIGURE 5 SHOWS A STONE OF CALCIUM OXALATE (98% MONOHYDRATE, 2% BLOOD AND PROTEIN)
Approx. 70-80% of all kidney stones diagnosed by medical staff are of a consistency of Calcium Oxalate. These cannot be dissolved. This crystallization is triggered by having too much Calcium or Oxalate in the urine, both of which can be the direct effect of bowel disease or immobilization after an injury or surgery. You are more at risk of calcium oxalate stones if you are descended from Anglo-Saxon ancestors.
FIGURE 6 SHOWS A STONE OF CALCIUM OXALATE (97% MONOHYDRATE, 3% PROTEIN AND BLOOD)
FIGURE 7 SHOWS A STONE OF CALCIUM OXALATE (10% MONOHYDRATE, 88% DIHYDRATE, AND 2% PROTEIN)
FIGURE 8 SHOWS A URIC ACID DIHYDRATE KIDNEY STONE.
Uric acid kidney stones are most common with people suffering from gout and who excrete large amounts of uric acid in the urine. These calculi cannot be seen on normal x-rays, but can be found on I.V.Ps, spiral C.T scans and sonographs. Uric acid stones are the only ones which can be readily dissolved by medical treatment.
FIGURE 9 SHOWS MAGNESIUM AMMONIUM PHOSPHATE HEXAHYDRATE STONES (STRUVITE).
Struvite or infection stones are typically associated with chronic urinary infection. They are easy to identify on x-rays, but these can be possibly fatal for kidneys, for they can grow silently, with only bladder symptoms occurring in the patient, unaware that the stones are filling the kidney and destroying it.
Miscellaneous stones like cysteine or xanthine are rare. The may be due to a certain medical condition or family factors, and can be treated with specialist care. These kinds of stones form about 20% of all cases and lead to jagged or branched stones forming called staghorn stones.
4. EFFECTS ON THE KIDNEYS:
Hypercalciuria, or excessive urinary calcium excretion, is defined as urinary excretion of more than 300mg of calcium per day for males on an unrestricted diet. Some physicians do not believe these measurements are accurate for diagnosis in cases of nephrolithiasis. This affliction usually goes hand in hand with a sufferer of Calcium stones.
This condition is excess oxalate in the blood and being passed in the urine. It is a very serious condition. Of all calcium oxalate stone sufferers, approx. 20-30 demonstrate some degree of hyperoxaluria.
There are 3 types of hyperoxaluria:-
- Primary hyperoxaluria (types I and II)
- Enteric hyperoxaluria
- Idiopathic hyperoxaluria
Primary hyperoxaluria is caused by a congenital defect.
Enteric hyperoxaluria is caused by a gastro-intestinal problem, usually accompanied by chronic diarrhea. Idiopathic hyperoxaluria (mild) is caused by calcium oxalate stones. This is due to high oxalate food substances or increased endogenous oxalate production.
This is the demise of citrate levels in the blood and urine. Citrates are an important inhibitor for kidney stones, and if these levels are persistently low, then more stones are likely to form.
5.1 LIFESTYLE CHANGES
Kidney stones recur in about 50% of all cases. There are steps which patients can take, in conjunction with the physician and dietician, which can prevent this from happening:-
- Drinking plenty of water.
- A reduction in the amount of dairy produce or foods high in oxalate, such as tea and chocolate, in the diet may help reduce chances of suffering kidney stones of Calcium Oxalate.
- Avoid large doses of Vitamin C.
- Avoid using antacids.
- Cut down the consummation of red meat, as this can help contribute to Uric Acid stones.
- Decrease the dosage of Sodium in the diet.
5.2 MEDICAL TREATMENT
The doctor may prescribe certain drugs to try and dissolve some of the stone. These drugs stabilize the pH of the urine, which is a key factor in crystal formation. The drug Allopurinol may be administered in cases of Hypercalciuria and Hyperuricosuria. Diuretics may also be given, such as Hydrochlorothiazide, which reduces the amount of Calcium released by the kidneys, into the urine. Sodium cellulose phosphate can help with sufferers of Hypercalciuria, as this binds Calcium in the intestine, and stops it from leaking into the urine. Thiola, the drug which helps reduce the amount of cystine in the urine, could be prescribed for cystine stone patients.
When a struvite stone is totally removed, doctors will monitor your urine, to make sure that is bacteria free, as this increases the chance of a recurrence. If one of these struvite stones cannot be removed, a drug called AHA or Acetohydroxamic Acid may be administered. In conjunction with antibiotics, AHA will kill off bacteria in the urine which could lead to recurrence.
Stones that do not pass themselves are usually treated with Extracorporeal Shockwave Lithotripsy or ESWL for short. This is a non-surgical treatment which uses high energy shock waves to break the stones into smaller fragments, about the size of a grain of sand, so that these can be passed out the body in the following few weeks. There are several different types of ESWL. One involves the patient to be reclined in a water bath, whilst the shock waves are transmitted round the skin. Some other machines use a cushion instead of water, but all patients are likely to be heavily sedated when the procedure is taking place. Complication may occur with this technique. As it involves the waves traveling through the skin and tissues until it reaches dense stone, there is a risk of blood being present in the urine and bruising or discomfort in the lower back and abdomen, for a few days after it has been given. This technique is very successful if the stone is 2cm in diameter or less. If the stone is considerably bigger than 2cm or the ESWL has not provided a good enough result, then other procedures are usually needed.
FIGURE 10 IS A DIAGRAM OF THE E.S.W.L. TECHNIQUE.
5.3 SURGICAL TREATMENT
Sometimes a procedure called Percutaneous Nephrolithotomy is the next logical step after an ESWL. In this procedure, the doctor makes a tiny incision in the back, and creates a tunnel directly into the kidney. Using an instrument called a Nephroscope; the surgeon locates and removes the stone. For larger stones, some type of energy probe may be needed to break up the stone into smaller parts, e.g. ultrasonic or electro hydraulic.
FIGURE 11 IS A DIAGRAM OF A PERCUTANEOUS NEPHROLITHOTOMY.
For stones which are lower down the urinary tract, a procedure called an Ureteroscope could be administered to the patient. No incision is made in this technique. Instead, a fibre optic instrument called an Ureteroscope is passed into the ureter, through the urethra and bladder. The surgeon then locates the stone and either tries to remove it, with a cage-like instrument, or uses some shock device to shatter it. A small stent may be left in the ureter for several days to help heal the lining of the tract. Before fibre optics were invented, physicians used a similar “blind basket” extraction method, but this is now out dated and should not be used, as it may damage the ureter permanently.
FIGURE 12 IS A DIAGRAM OF THE URETEROSCOPY METHOD.
5.4 RESEARCH ON KIDNEY STONES
Although kidney stone removal has a high success rate, new research is being done to answer some of the questions that cannot be answered. Not enough knowledge of this affliction exists, and scientists are currently looking in great detail into studies which could answer things like:-
- Why do some people continue to have recurrence of stones?
- How can doctors predict, or screen those who are at risk from getting stones?
- What are the long-term effects of Lithotripsy?
- Do genes play a role in stone formation?
- What are the natural substances which are present in urine that help inhibit stone formation?
Recent research from one leading medical establishment has found in its results from studies that instead of agreeing with the views of the General Medical Council, they have stated that sufferers of Calcium stones should increase the amount of dairy produce in their diet, as this helps “reduce” the chance of Calcium Oxalate build up. This new research is a total contradiction to earlier studies which found that a high calcium intake was a factor in stone formation. Researchers are also looking into new drugs with fewer side effects. Hopefully in years to come, some of these questions will be answered and we will have a better understanding of this strange phenomenon.
This report has shown that Renal Calculi are a major problem for about 10% of the public. And although that there are precautionary measures to follow and medical techniques to remove these growths, still not enough is known about them to stop the pain and suffering of the victims, or to inhibit the formation of the stones, in the people it will affect in the near future. Drug companies are putting a lot of money into research, which is a fundamental part of medicine. But not knowing what directly causes them, or who will be a victim, means that anyone could be the next victim of arguably the worst pain man could suffer.
I have used the following materials to help me research this project:
- E – Medicine.com/ kidney stones 2002.
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) report on kidney stones 2001.
- The American Medical Association’s the kidney.com.
- The New England Journals on Nephrology.
- Boston University Urology Committee Journals on Kidney Stones and Diseases.
- N.H.S Kidney Information Journal 1998.
- Hospitals of California Kidney research 2000.
- Louis C. Herring and co laboratories kidney fact page 2001.
The following are the sources for the figures in this report:-
- FIGURE 1, taken from Hospitals of California Kidney research.
- FIGURE 2, taken from N.H.S Kidney informational journal.
- FIGURES 3-9, taken from Louis C. Herring and Co web pages.
- FIGURES 10-12, taken from N.H.S Kidney information journal.