[Prevention of nephrolithiasis. Established strategies and new concepts]

[Urolithiasis in children--rational diagnosis, therapy, and metaphylaxis]

With a proportion of 1-5%, children constitute only a small number of all patients with urolithiasis. Nevertheless, pediatric stone disease is an important health care problem because of the high recurrence rate and the threat of progredient renal function impairment with consecutive loss of quality of life. Modern therapies, especially extracorporeal shock wave lithotripsy (ESWL), ureteroscopy (URS), and percutaneous nephrolithotomy (PCNL), have caused a revolution in the operative treatment spectrum. Open surgery is required for stone removal only rarely, such as for the simultaneous repair of urinary tract anomalies. The minimally invasive modalities of modern stone therapy - mainly ESWL as the treatment of first choice - have led to widespread disregard of stone metaphylaxis. The important principle that says an urinary stone is just a symptom and not the cause of the disease is often forgotten. So it must be noted that despite the high standard of care in Germany, not all problems regarding urinary stone disease are being resolved, particularly in childhood. This article presents the current knowledge of the most important aspects of stone therapy and the methods of treatment in children.

[Silica-containing urinary stones--clinical issues to keep in mind]

Formation of calculi in efferent urinary passages is always due to supersaturation of urinary calculi substances and associated increased crystallization. Apart from the typical calculi, consisting of calcium oxalate, inorganic phosphates, uric acid or cystine, there are occasional signs of rare substance classes. Although more than 50 silicate stones have already been reported internationally, this stone entity remains relatively unknown. In particular, the occurrence of silicate stones in the absence of magnesium trisilicate abuse is extremely rare. A medium-sized left-sided ureterolith was removed from a 54-year-old male patient using a ureteroscope. X-ray diffraction showed it to be a compound stone consisting of 40% silicate. The patient, who in 1986 was living close to the nuclear reactor accident in Chernobyl, showed no signs of a constant uptake of magnesium trisilicate. However, he had undergone partial (2/3) gastrectomy 4 months before for a drug-refractory gastric ulcer, which had been diagnosed at the end of the 1980s and treated with excessive dosages of a magnesium trisilicate antacid preparation until the time of the operation. The patient had also been suffering from unstable angina pectoris since 1986 and treated with Pentalong (pentaerythrityltetranitrate) for 17 years. We were also able to detect silicium dioxide in components of this drug using X-ray diffraction. Silicate uroliths are extremely rare but they can be clearly identified by X-ray diffraction or infrared spectroscopy and distinguished from artifacts or quartz pebbles. Formation of calculi can be prevented by increasing diuresis as well as switching to a different drug and reducing the dosage.