Kidney stones (from the Latin calculus, pebble) are accretions (crystalline) solids of dissolved minerals (the whewellite) in urine and found in the kidneys or ureters. Also known as nephrolithiasis, urolithiasis, urinary stones. They range in size from that of a grain of sand to that of a golf ball. The largest calculations, called spineless, mold inside the kidney, thus having the appearance of coral branches. Kidney stones are typically removed by the stream of urine if they grow to a relatively large before passing (on the order of a few millimeters), obstruction of a ureter and dilated renal the urine can cause severe pain, "colic", serving general in the side and lower abdomen.
Conventional wisdom has held that consumption of too much calcium can aggravate the development of kidney stones, since the most common type is composed of calcium oxalate. However, experience shows that diets with reduced calcium intake is associated with risk of gallstones higher and vice versa. The relatively dense calcium renders these calculations radiopaque and can be detected by x-ray of the abdomen. Ultrasound, CT, digital radiography, are diagnostic tests for more accurate detection of kidney stones.
The annual incidence is estimated at 0.5% per year. The prevalence (total cases) is about 5%. The probability of being reached during a lifetime is estimated at 10-15%. It is superior to 25% in the Middle East. It is essentially a recurrent disease with almost 50% recurrence at 10 years. This disease is more common in men. However, the gender difference fades with age.
An increased concentration of poorly soluble compounds in urine "concentrated" is a trivial factor. This explains the higher incidence of disease in cases of dehydration may be secondary to high heat, fever or other reasons.
The calcium stones are enhanced by hypercalcemia (high blood calcium) whose causes are multiple. Hypercalcemia can be induced by such a high consumption of mineral water rich in calcium and the residue is dry sometimes 4 times that of a water source.
The uric acid calculi are favored by acidic urine in patients with uric acid level in blood.
In fact, the mechanism is multifactorial (many intertwined causes) and often complex, combining genetic, dietary factors and metabolic abnormalities acquired.
It is in nearly 80% of cases of calcium oxalate. other types of stones are more rare cystine (an amino acid found in people suffering from cystinuria), uric acid or other materials.
Calculations can also be composed of struvite (magnesium ammonium phosphate) (10% of cases). The formation of struvite stones is associated with the presence of a bacterium (Klebsiella, Serratia, Proteus, Providencia species), which converts urea into ammonium and it is most commonly Proteus mirabilis.
In nearly 40% of calculations, they involve several compositions to the same stone.
Kidney stones are usually idiopathic and asymptomatic until they obstruct the flow of urine. Symptoms can include acute flank pain (called renal colic), nausea and vomiting, restlessness, dull or acute pain, hematuria, and fever in cases of superinfection. The acute renal colic is described as one of the worst pain ever. But some people have no symptoms until their urine contains blood (hematuria), which may be the symptom of nephrolithiasis.
More rarely, when the stone reaches the lower urinary tract, it may manifest as difficulty with urination (dysuria).
There is usually no renal failure, impairment is unilateral.
* Ideally, we found the stone in the urine which signs the diagnosis.
* Apart from the typical clinic generally, the presence of blood in the urine revealed a reactive band, encourages conduct additional tests:
* Abdominal ultrasound observing the kidneys and urinary tract shows a dilated collecting system and renal calices, the calculations are not directly visible but by the appearance of a shadow cone signing the shadow calculation.
* The plain radiograph or CT scans shows calculations radio opaque projection urinary tract.
* The intra-venous urography requires the rapid injection of about 50ml of iodine dye into the bloodstream which will be purified by the kidneys. After taking X-ray pictures to precise time, the (s) calculation (s) and the contrast is highlighted showing a dilated urinary tract upstream of the calculation that stops the progression of the contrast in urinary tract). This technique is much less used since the availability of ultrasound.
* Abdominal CT scan tends to gradually take the place of intravenous urography.
* MRI = rarely practiced.
* Analgesics, spasmolytic, anti-inflammatory drugs in the treatment of renal colic crisis.
* A number of drugs have some effectiveness in facilitating the "transition" of the stones: are calcium channel blockers, especially in combination with corticosteroids and alpha-blockers.
* Fluid restriction (treatment of the crisis. To treat the cause, it may instead force the fluid intake to "dilute" the substances that crystallize). It helps in reducing the inflow to have a urine output lower, and theoretically, less "push" on the calculation. This point is still debated, but generally preferred fluid restriction during the crisis.
* The times called lithotripsy lithotripsy (anglicism), by external shock waves called "LEC" that break the computation into small pieces which facilitates the transition was made from the late 80s. This method can however be responsible for renal failure in some cases.
* Surgery (removal of the load after surgical opening of the upper urinary tract, which can sometimes be done by laparoscopic technique)
* Cystoscopy and removal by internal maneuvers (calculations have migrated into the lower ureter)
* Proper hydration is essential to dilute the compounds responsible.
* A diet low salt and low in protein may reduce the frequency of recurrent calcium stones.
* Decreased intake of oxalates may be useful but is difficult in practice.
* If hypercalcemia is found, treatment of the latter may significantly improve the rate of recidivism. Similarly, if hyperuricemia, drug therapy would diminish this complication.
Read also Chronic kidney disease