[What kind of stone prevention for whom? Risk-adjusted metaphylaxis following urinary stone disease]

Urolithiasis--an interdisciplinary diagnostic, therapeutic and secondary preventive challenge

BACKGROUND

The prevalence of urolithiasis in Germany is 4.7%; its incidence has trebled in the last three decades. The risk of recurrence is 50-80%, depending on the type of stone, unless secondary prevention is instituted. Risk-adapted secondary prevention lowers this risk to 10-15%.

METHODS

This review is based on publications retrieved by a selective search in PubMed using the key words "urolithiasis," "urinary stones," "epidemiology," "lithogenesis," "biominerals," "risk factors," and "diagnosis, therapy, metaphylaxis." These publications were evaluated with the aid of the urolithiasis guideline of the European Association of Urology.

RESULTS

Acute renal colic can usually be diagnosed without sophisticated equipment. Stones can be dealt with by a variety of techniques depending on their size and location, including extracorporeal shock-wave lithotripsy, ureterorenoscopy, percutaneous nephrolitholapaxy, and open surgery. Most ureteric stones of diameter up to 5 mm pass spontaneously. 75% of patients have no complications. The basic evaluation needed for secondary prevention can be carried out by any physician on an ambulatory basis. In the 25% of patients who have complications, a more extensive interdisciplinary evaluation of metabolic parameters should be performed in a clinical center for urinary stones.

CONCLUSION

Urolithiasis has many causes and can be treated in many different ways. An extensive metabolic work-up is often necessary for secondary prevention. The various treatment options must be considered for their suitability in each individual patient. Robust data are now available on surgical and interventional methods, but there are as yet no high-quality trials of secondary prevention. Further research should concentrate on the etiology and pathogenesis of urolithiasis.

[Qualitative and quantitative analysis of urolithiasis with the Rietveld method (x-ray diffraction)]

BACKGROUND

The Rietveld method is one of the most innovative and most important applications in x-ray diffraction and has now, for the first time, been applied to standard-free precise quantitative crystallographic analysis of urinary stones.

MATERIAL AND METHODS

The capability of the Rietveld method was demonstrated by analysis of a synthetic mixture of five typical urinary stones: whewellite, hydroxylapatite, brushite, struvite, and uric acid, with 20 weight % for each pure component.

RESULTS

The quantitative phase analysis (Rietveld method) yielded a mean absolute error of only 1.6% for the weight fractions of the single urinary stone components. The largest error in weight fraction, 2.3%, occurred with hydroxylapatite, caused by the typical insufficient crystallinity.

CONCLUSION

Crystallographic analysis of complex urinary stones with the aid of x-ray diffraction, in combination with a Rietveld structure refinement, is the method of first choice for qualitative and quantitative phase analysis. With this tool, significant changes in weight fractions for recurrent urinary stones can be precisely detected, with therapeutic consequences.

[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.