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| These are some of the larger passed fragments of a 1-cm kidney stone that was blasted using lithotripsy. The stone was composed of calcium oxalate. (Photo credit: Wikipedia) |
KIDNEY STONES IN THE NEWS.
OVERVIEW
- Kidney stones affect approximately 12 percent of men and 5 percent of women by age 70.
- Treatment is available to effectively manage most stones.
- Recurrence can occur at a rate of up to 5 percent per year.
FORMATION OF THE STONE
There are different types of kidney stones.
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| KUB stone (Photo credit: Wikipedia) |
- calcium kidney stones.
- oxalate kidney stones.
- cystine kidney stones.
- uric acid kidney stones.
When these substances are at high levels in the urine they precipitate out of solution and become solid crystals which get stuck somewhere in the tract from the kidney to the ureter and bladder, the kidney stone then forms particularly at narrow points along the way.
Usually, the stone will be moved through the tract by the flow of urine until entering the bladder and eventually be expelled.
A larger kidney stone may cause the sensation of kidney pain as it moves and damage to the walls of the ureter or bladder thus causing blood in the urine.
If the kidney stone is too large it may not enter the ureter at all.
Instead it enlarges to fill the entire kidney outflow tract called the hilum. These kidney stones may take on a specific shape like the horns of a stag. They are termed staghorn kidney stones. They may cause kidney obstruction, kidney infection and kidney failure if untreated.
KIDNEY STONE RISK FACTORS
Patients may be at risk for kidney stones if:-
KIDNEY STONE SYMPTOMS INCLUDE
DIAGNOSIS OF KIDNEY STONES
- High concentrations of calcium, oxalate or uric acid in the urine.
- Low pH (urine too acidic)
- Concentrated urine (poor fluid intake)
- Not eating enough calcium (you absorb too much oxalate if calcium is low)
- Eating too much calcium
- High sugar intake
- High protein intake.
- High sodium intake.
MEDICAL CONDITIONS MAY ALSO PREDISPOSE TO KIDNEY STONE FORMATION
SOME QUICK FACTS.
If you have previously had a kidney stone you are at increased risk for a new kidney stone.
Drinking high volumes of grapefruit juice has been linked to kidney stones.
Green tea and coffee lowers the risk of kidney stones
Beer and wine are ok.
A normal calcium intake may protect you from kidney stone formation
A high calcium intake causes kidney stones as well as a low calcium intake too.
Dietary fibres such as wheat and cereal reduces risk of kidney stone formation.
Excessive vitamin C intake increases the risk of kidney stone formation.
KIDNEY STONE SYMPTOMS INCLUDE
KIDNEY PAIN
This can be very severe pain which is never quite relieved by changing position. Causing some amount of restlessness walking around or twisting and turning. The pain occurs in episodes of intensification followed by slightly reduced pain a phenomenon known as colic.
Kidney pain may be associated with vomiting or nausea.
Kidney pain is caused by obstruction of the ureters and stretching of the tissues around the kidney.
The passage of the stone through the urinary tract is associated with a downward moving of the pains which ultimately enter the flank and may even continue down to the groin. Classically described as loin to groin pain.
On the other hand..........
Some patients have large kidney stones for several years with only a dull ache or no symptoms at all. These kidney stones however can grow so large they cause a silent slowly evolving kidney failure. These kidney stones are associated with recurrent kidney infections which become more difficult to treat with time requiring removal of the kidney stone.
Blood in the urine.
Damage to the delicate tissues of the kidney and urinary tract is the cause of bleeding. Bleeding may discolour the urine making it red or near to red in the spectrum. However the bleeding may be invisible to the naked eye and require a dipstick test.
Gravel.
This refers to the passage of small kidney stones which have the consistency of gravel this is more common in uric acid kidney stones.
DIAGNOSIS OF KIDNEY STONES
Kidney Stones may be diagnosed by any of the following tests :-
A CT scan of Kidney Ureter and Bladder.
This is a non invasive test similar to an xray but more advanced. In which actual internal anatomy can be seen in 3d. Kidney stones show up easily with this test. It is also possible to learn if there is kidney obstruction or any obvious damage to the kidney at the same time. This test has a higher yield when the patient actually complains of kidney pain.
Ultrasonography of the kidney ureter and bladder.
This test is more dependent on the skill of the observer than the previous test. It is based on sound waves traveling through tissues. The kidney stone blocks the sound waves if large and can be seen as a shadow on the screen. Small kidney stones are frequently missed. This test avoids the use of radiation and may be the best choice in a pregnant patient complaining of kidney pain. Overall it is inferior to CT scan.
Plain Abdominal xray.
Moderately reliable for larger calcium containing kidney stones. Small uric acid kidney stones may be missed. This test is inferior to CT-SCAN
IVP
Dye that shows up white on xray is injected to the blood stream. It passes through the kidney and enters the urine. It outlines the areas of the urinary tract that can be filled by the dye. The kidney stone is seen as a filling defect. This test can assess to some degree function of the kidney and is the gold standard for determining if a small kidney stone is present.
Unfortunately the dye may cause a significant allergic reaction. This test is generally avoided in patients with a history of any allergies.
General testing to identify a metabolic problem as an underlying cause of kidney stones should also be done.
KIDNEY STONE TREATMENT
When kidney pain is severe the patient may have bouts of vomiting leading to
dehydration. If dehydration occurs the flow of blood through the kidney is reduced. The kidney creates urine from blood, so urine flow is further reduced this may prolong the passage of the kidney stone.
Fluid resuscitation via IV fluid should be commenced simultaneously as soon as possible. Sometimes giving lots of fluids into the vein will cause the kidney to produce more urine and flush the kidney stone out.
Kidney pain is frequently severe and is caused by muscle spasm, a muscle relaxing drug such as Baralgin, in combination with aspirin based pain killers such as Voltaren, Cataflam, Brufen should be used however strong painkillers may be required such as narcotics and if necessary given IV.
If vomiting occurs the patient is usally admitted to hospital. If the kidney stone is larger than 9 millimeters it is unlikely to pass from the kidney on its own.
If the patient passes urine it must be examined for the presence of any kidney stones by passing the collected urine through a strainer.
If the kidney stone is not passed out then a special procedure may be required such as:-
ESWL (sound waves)
- Depending on the density of the stone and postion and size the stone may be destroyed by sound waves targetted at the stone in a non invasive manner.
PNL- (microsurgery)
- Percutaneous nephrolithotomy. If the stone is very large microsurgery may be performed through small holes in the skin to break up the stone.
Ureteroscopy- (a scope is passed)
A fibreoptic scope is passed up the ureter, however it cannot reach all the way to the top of the kidney. So the stone has to be at least half way down for this to be effective.
KIDNEY STONE PREVENTION
To decrease the chances of another kidney stone:-
You need to determine the cause of the first stone and treat the problem. This is accomplished by analysing the stone to determine its primary component.
General measures such as increased fluid intake to dilute the urine and flush the kidney.
Making the urine more alkaline with lime juice or citric acid in select cases.
Dietary changes.
Surveillance with CT scan or IVP for new stones that have not yet caused a problem is possible. The smaller the stone the easier to treat.
Using the DASH diet.
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