Kidney stones (latin calculus, pebble) are accretions (crystal) solid minerals dissolved (the whewellite) in the urine and which is found in the kidneys or ureters. Also known as néphrolithiase, urolithiasis, urolithiasis. They have various sizes, from that of a grain of sand to that of a golf ball. The largest calculations, known coraliformes, mold inside the kidney, thus having the appearance of coral branches. Kidney stones are typically evacuated by the stream of urine, they grow up to a relatively large size before moving (on the order of a few millimeters), obstruction of a ureter and kidney expansion in the urine can cause severe pain, "renal colic," serving the general side and lower abdomen.
The conventional wisdom has argued that the consumption of too much calcium can aggravate the development of kidney stones, since the most common type is composed of calcium oxalate. However, the accumulated experience shows that schemes with reduced calcium intake are associated with a risk of gallstone higher and vice versa. The relatively dense calcium makes these calculations radio-opaque and they can be detected by an X-ray of the abdomen. The ultrasound scanner, digital radiography, are diagnostic tests for the most accurate detection of kidney stones.
The annual incidence is estimated at 0.5% per annum. Its prevalence (the total number of cases) is approximately 5%. The probability of being reached during a lifetime is estimated at 10-15%. It is over and reached 25% in the Middle East. It is essentially a recurrent disease with nearly 50% of recidivism to 10 years. This disease is more common in humans. However, the difference between men and women fades with age.
An increase of concentration of poorly soluble compounds in a urine "concentrated" is a trivial factor. This explains the greater frequency of the disease in cases of dehydration may be secondary to strong heat, fever or other reasons.
The calculations are calcium favoured by hypercalcémies (high calcium in the blood) whose causes are multiple.
The calculations of uric acid are favoured by acidic urine in patients with a rate of high uric acid in the blood.
In fact, the mechanism is polyfactoriel (several causes entangled) and often complex, involving a genetic origin, dietary factors and metabolic abnormalities acquired.
It is in nearly 80% of cases of calcium oxalate. other types of calculations are more rare: cystine (amino acid found in people suffering from cystinurie), uric acid or other materials.
The calculations can also be composed of struvite (magnesium ammonium phosphate) (10%). The training calculations struvite is associated with the presence of a bacterium (Klebsiella, Serratia, Proteus, Providencia species), which converts urea to ammonia, which is mostly Proteus mirabilis.
In nearly 40% of calculations, they combine several compositions for the same stone.
Kidney stones are usually idiopathic and asymptômatiques until they obstruct the flow of urine. Symptoms may include severe pain in the side (known as renal colic), nausea and vomiting, restlessness, deaf or acute pain, hematuria, and fever in case of infection. The acute renal colic is described as one of the worst pain there is. But some people have no symptoms until their blood contains urine (hematuria), which may be the symptom of a nephrolithiasis.
More rarely, when gallstone reached the low urinary tract, it may be manifested by a difficulty in urination (dysuria).
There is usually no renal failure, the damage is unilateral.
* Ideally, the stone is found in urine which indicates the diagnosis.
* Apart from the typical clinical generally, the presence of blood in the urine revealed by a dipstick, an incentive to conduct reviews:
* The abdominal ultrasound observing the kidneys and urinary duct shows an expansion of pyélon and chalices kidney, the calculations are not directly visible but by the appearance of a cone of shadow signing the shadow of calculation.
* The X-ray tomography, or with simple calculations show radio opaque projection of the urinary tract.
* Urography intra-venous injection requires quick about 50ml of iodized dye into the bloodstream which will be refined by the kidneys. After taking X-ray pictures to precise time, calculation and the contrast are highlighted showing an expansion of the urinary tract upstream of calculation to stop the progression of the contrast in urinary tract). This technique is much less used since the availability of ultrasound.
* The scanner abdominal tends to gradually take the place of the urography intra-venous.
* Antalgiques, spasmolytic, anti-inflammatory in the treatment of renal colic crisis.
* A number of drugs have some efficiency to facilitate the passage of gallstone: these are the calcium channel blockers, especially associated with corticosteroids and alpha blockers.
* Restriction water (treatment of the crisis. For the treatment of the case, it is sometimes necessary to force the contrary water intakes for "dilute" the substances that crystallize). It helps in reducing the intake of water, have a urine production lower, and theoretically, at least "push" on the calculation. This point is still debated, but generally prefers the restriction water during the crisis.
* The lithotripsy sometimes called lithotripsy (anglicism), by external shock waves known as "LEC" calculating that break into small pieces which facilitates the passage, was introduced from the end of 80 years. This method, however, may be responsible for renal failure in some cases.
* Surgery (removal of calculating after opening surgical urinary tract high, which can sometimes be made by technical coelioscopique)
* Cystoscopy and ablation maneuvers (internal calculations have migrated in the lower ureter)
* Proper hydration is crucial in order to dilute the compounds responsible.
* A diet low salt and low in protein may reduce the frequency of recurrent calcium calculations.
* A decrease of ingestion of oxalates can be useful but it is difficult in practice.
* If hypercalcaemia is found, treating the latter can improve significantly the rate of recidivism. Similarly, in case of hyperuricemia, a drug treatment latter decreased this complication.
* Fragmentation of calculation by laser
* Kidney stones have no link with gallstones.
Some patients famous: Michel de Montaigne, Isaac Newton, Martin Luther. The writer Isaac Asimov had problems with kidney stones, and describes how his pain was treated with morphine, adding that it feared becoming dependent on where that would have a greater need.
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