Gernot Schubert

Urolithiasis Through the Ages: Data on More Than 200,000 Urinary Stone Analyses

PURPOSE The incidence and prevalence of urolithiasis are increasing but clinicians also have the impression that gender and age distributions of stone formers are changing. Moreover, regional differences in stone occurrence and composition have been observed. We analyzed such trends based on a large series of urinary stone analyses. MATERIALS AND METHODS A total of 224,085 urinary stone analyses from 22 German centers were evaluated to determine the incidence of stone composition and identify age and gender distributions from 1977 to 2006. A subset of 58,682 stone analyses from 1993 to 2006 was available to identify regional differences in stone composition in Germany. RESULTS Calcium containing calculi were most common in each gender. The overall male-to-female ratio of 2.4:1 increased from 1977 (1.86:1) to 2006 (2.7:1). The predominance of male calcium stone formers was even higher among elderly patients with a 3.13:1 ratio at ages 60 to 69. Since 1997, we observed a tendency toward an increasing incidence in middle-aged patients at ages 40 to 49 years. While the rate of infection stones constantly decreased, the incidence of uric acid calculi remained stable with an overall rate of 11.7% in males and 7.0% in females with a peak at higher ages. Cystine stones remained rare at 0.4% in males and 0.7% in females. In terms of regional analyses we noted great variation in stone composition in the 2 genders. Uric acid stones were more common in the eastern and southern regions but infection stones were mostly seen in eastern regions. CONCLUSIONS In what is to our knowledge the largest series of stone analysis reported to date we identified an age and gender relationship of stone formation and composition. Regional variations are common and underline the influence of living habits, diet and standard of medical care on urinary stone formation.

Comparison of Extracorporeal Shock Wave Lithotripsy and Ureteroscopy in the Treatment of Ureteral Calculi: A Prospective Study

146 patients whose ureteral stones did not pass spontaneously participated in a prospective study on optimal management. Patients were offered two treatment options: extracorporeal shock wave lithotripsy (ESWL) and ureteroscopy (URS). The stone was treated with the technique preferred by the patient. In case of treatment failure after first-line therapy, patients again could decide on how to proceed. Stone analysis could be obtained from 72.6% patients. ESWL was the primary treatment in 66.4% patients. In 2 patients, ESWL was the secondary treatment after failed URS. URS was the first-line therapy in 33.6% patients. In 29 patients URS was done after failed ESWL. For analgesia, sedoanalgesia or spinal anesthesia were used. Analgesia was required in 74.2% ESWL and 100% URS sessions. Following ESWL, 70.1% patients became stone free. In 29.9% ESWL failed. Distal stones had a higher failure rate than proximal or mid-ureteral calculi. Distal stones treated without success were significantly larger than those treated successfully. Failures were switched to URS. Stone analysis could be obtained in 26 patients with failed ESWL: 23/26 consisted of pure whewellite or mixed whewellite stones. Clinically relevant complications were not observed. After URS, 94.9% of the patients became stone free. In distal stones, the stone-free rate was 97.5%. There was only 1 relevant complication: a proximal ureteral lesion requiring surgical repair. Our study demonstrates that URS is a safe and highly effective treatment option for ureteral stones. In patients with distal ureteral stones, it should be offered as a first-line treatment. When whewellite is expected as the stone mineral, URS is the treatment of choice.

480 UROLITHIASIS THROUGH THE AGES: DATA FROM MORE THAN 200,000 URINARY STONE ANALYSES

From the Departments of Urology, Sindelfingen-Boeblingen Medical Center, University of Tubingen (TK, GWN), Tubingen, Zeisigwald Clinics Bethanien (DF), Chemnitz and Malteser Hospital St. Hildegardis (DBL), Cologne and Department of Traumatology and Orthopaedics, Vivantes Klinikum Spandau (ABS) and Urinary Stone Laboratory, Institute of Laboratory Diagnostics, Vivantes Klinikum Friedrichshain (GS), Berlin, Germany

Uric acid monohydrate—a new urinary calculus phase

In our laboratory more than 100,000 urinary calculi have been analysed since 1972. Amongst this huge sample, 15 specimens originating from a total of eight patients were observed showing similar characteristics but escaping unambiguous identification with any of the substances that have been described so far in urinary concrements. Therefore, the unknown substance was submitted to a more extended analytical regimen. Structural analysis by x-ray crystallography turned out to be most successful, identifying the unknown material as uric acid monohydrate. Uric acid monohydrate crystallizes in the monocline space group P21/c. Within the crystal, uric acid and water molecules form continuous layers by hydrogen bonds. This is in contrast to uric acid in its water free and its dihydrate forms, which both crystallize by forming 3-dimensional networks To the best of our knowledge , the existence of a monohydrate form of uric acid has not been reported so far. Accordingly, this is the first report on uric acid monohydrate as a urinary stone component. The frequency of only 0.015% in our survey indicates that uric acid monohydrate is rarely the main component in concrements, in contrast to uric acid and uric acid dihydrate with frequencies of 10% and 6%, respectively. The infrared spectrum of uric acid monohydrate is very similar to that of the other crystal forms of uric acid. Because of this similarity and its low frequency, uric acid monohydrate may have been overlooked as a component of urinary concrements. X-ray diffraction allows for better differentiation in routine stone analysis. All samples of uric acid monohydrate were found by solid state NMR spectroscopy to be highly contaminated by amorphous material. This material consisted of long aliphatic chains reminiscent of lipids and fatty acids, respectively. Concrements consisting of other forms of uric acid or urate lacked this amorphous component. Therefore, a role of this aliphatic material has to be taken into consideration when discussing the conditions that may favour the rare formation of concrements from uric acid monohydrate. As for as the metabolic situation of the affected patients is concerned, no common peculiarities became evident by a retrospective survey.

Urinary Stone Formers with Hypocitraturia and ‘Normal’ Urinary pH Are at High Risk for Recurrence

Background: Citrate is one of the most important inhibitors in urolithiasis. Hypocitraturia is a common risk factor in stone formers. Citrate excretion is regulated – amongst others – by acidosis and protein intake. A considerable number of stone formers, however, show hypocitraturia in the presence of normal urine pH levels. This is potentially due to defects in the renal tubular citrate carriers (NaDC 1 and 3) which may be genetically determined. Patients and Methods: 350 consecutive stone formers were examined. Exclusion criteria were urinary tract infection, hypokalemia, and steatorrhea. The following parameters were measured: serum: creatinine, calcium, potassium, and uric acid; urine: pH profiles, citrate, calcium, uric acid, ammonia, urea, and creatinine. Results: 83/350 patients were hypocitraturic (48 males, 35 females). 14/83 had low urine pH (≤6), 69/83 showed normal levels (>6). In the latter group there was a significantly higher recurrence rate (23 vs. 9%). The two groups were not different in serum parameters apart from uric acid. In urine, only pH and calcium (males) were significantly lower in the first group. Citrate did not correlate with urine pH and creatinine in the hypocitraturia-normal pH group, only with calcium in both sexes and urea and ammonia in females. In the hypocitraturia-low pH patients, there was no significant correlation between citrate and any other parameter tested. Conclusions: Hypocitraturia with normal urine pH is an entity indicating a high risk for recurrence. Since there was no correlation between citrate and pH, urea and ammonia, respectively, citrate excretion is not regulated in these patients as usual. There may be a link to calcium excretion. Potentially, these patients have defects in the renal tubular citrate carriers which may be genetically determined. Genetic examinations should be performed to elucidate a potential genetic disorder in hypocitraturia-normal pH stone formers.

Overweight and Obesity: Risk Factors in Calcium Oxalate Stone Disease?

Introduction. Several studies showed an association of overweight and obesity with calcium oxalate stone disease (CaOx). However, there are no sufficient data on the influence of body weight on the course of the disease and the recurrence rate. Patients and Methods. N = 100 consecutive stone formers with pure CaOx were studied. Different parameters were investigated. According to the BMI, patients were divided into three groups: (1) BMI ≤ 25; (2) BMI 25.1–30; (3) BMI > 30. Results. N = 32 patients showed a BMI ≤ 25, n = 42 patients showed a BMI of 25.1–30 and n = 26 patients showed a BMI ≥ 30. The groups differed significantly concerning BMI (by definition), urine pH, and urine citrate. The recurrence rate was not significantly different. Discussion. Our study demonstrated that body weight negatively influences single risk factors in CaOx, but obesity is not a predictor for the risk of recurrence in CaOx.

E84 Papillary calcifications – a new prognostic factor in idiopathic calcium oxalate urolithiasis (CaOxU)

Metabolic evaluation is not suitable to forecast the course of the disease in idiopathic calcium oxalate stone formation (iCaOxU). An important pathway in CaOx stone formation is the overgrowth on interstitial apatite papillary plaques. Therefore, we studied whether the extent of such plaques may be used as a prognostic factor in CaOxU. Prospectively, we studied n = 100 patients with iCaOxU. For stone analysis, X-ray diffraction/polarizing microscopy was used. During flexible ureteroscopy and flexible percutaneous nephrolithotomy, all the renal papillae were inspected, counted and the severity of calcifications assessed. A calcification index (CI) was calculated: sum of the No. of papillae × calcification grade (1–3) × No. of calcified/total No. of papillae. Furthermore, the following parameters were examined in all patients: age, sex, BMI, arterial blood pressure, stone episodes, DM; blood: creatinine, glucose, uric acid, calcium, sodium and potassium; urine: pH, volume, calcium, uric acid, citrate, ammonia and urea. Using the statistic programme Prism 5 (GraphPad), summary statistics and non-parametric correlations (Spearman) and their significance were calculated. The CI correlated significantly (r = 0.37; p = 0.012) with the No. of stone episodes. Apart from citrate (r = 0.51; p = 0.002), none of the conventional metabolic parameters correlated significantly with the No. of stone episodes. Paradoxically, the citrate excretion—although citrate being an inhibitor of CaOx stone formation—positively correlated to the recurrence rate. The endoscopic assessment of papillary plaques/calcifications and the calculation of the CI are a more suitable prognostic factor in CaOx than conventional metabolic evaluation.

Unverzichtbar in der Metaphylaxe

ZusammenfassungBei Harnsteinrezidiven kann sich die Zusammensetzung der Steinkomponenten ändern. Um eine effektive Nachsorge zu gewährleisten, ist eine Harnsteinanalyse daher unerlässlich.