Induced urinary crystal formation as an analytical strategy for the prediction and monitoring of urolithiasis and other metabolism-related disorders.

Crystal formation reflects the entire composition of the surrounding solution. In case of urolithiasis, induced crystal formation in native urine has led to the development of the Bonn-Risk-Index (BRI), a valuable tool to quantify an individual's risk of calcium oxalate urolithiasis. If the progression of a disease is associated with characteristic changes in the activities of urinary components, this leads to an altered urinary crystallisation capacity. Therefore, the results of induced urinary crystal formation can be used to detect and monitor any disease linked to the altered urinary composition. Since crystal formation inherently takes into account the entire urinary composition, the influence of the disease on individual urinary parameters does not have to be known in order to monitor the consequent pathologic alterations. In this paper, we review the background of urinary crystal formation analysis and describe its established application in urolithiasis monitoring as well as potential further fields of clinical application.

Metabolic stress response patterns in urinary compositions of idiopathic calcium oxalate stone formers, patients with chronic bowel diseases and controls.

Emotional stress is associated with e.g. increased hormone release, high blood-sugar level and blood pressure. Stress clearly affects metabolism. Whether chronic stress exposure leads to altered urinary compositions with increased risk of CaOx; urolithiasis was examined by investigating the relation between stress burden and urine composition. 29 controls (CG), 29 CaOx stone formers (SF), and 28 patients with chronic inflammatory bowel diseases (CIBD) were advised to avoid unfavorable aliment. Any urolithiasis-related medications were stopped. At day 5, a 24-h urine was collected and comprehensive urinalysis performed. AP (CaOx) index was calculated. Subjects completed a questionnaire designed to measure perceived stress ("Trier-Inventory-of-Chronic-Stress"). Mean AP (CaOx) in CG, SF and CIBD amount to 0.8 (+/-0.3), 1.2 (+/-0.7), and 1.9 (+/-1.2), respectively. Increased AP (CaOx) in SF is mainly attributed to an increased effect of calcium and oxalate, whereas in CIBD this is additionally caused by a reduced effect of citrate, magnesium and volume. Stress dimensions are correlated to any investigated urinary parameter with an absolute value of r < or = 0.600; some correlations are statistically significant: whereas in SF only one combination, "lack of social recognition" versus calcium, shows significance, in CIBD various combinations are significantly related. In particular, sodium excretion increases with stress. In CG, some stress dimensions are directly related to citrate; with increasing stress, protection against CaOx crystallization tends to increase. It could be shown that stress load and urinary composition are related by statistical means. The observed metabolic stress response patterns in urinary compositions are different for the distinct groups, thereby, reflecting a conclusive picture. This is in particular in CIBD, for which a link between stress and inflammatory activity and between inflammatory activity and altered urinary composition is well established.

Correlations between the autonomic modulation of heart rate, blood pressure and the pupillary light reflex in healthy subjects.

Information on autonomic modulation can be derived from different organs that are innervated by the sympathetic and the parasympathetic nervous system, when assessing e.g. heart rate or blood pressure fluctuations or the pupil's reaction to light. Correlations between parameters from different target organs might reveal information on hierarchically higher centres of autonomic integration. Here, we obtained parameters of heart rate variability, blood pressure variability, baroreflex function and light reaction pupillography from 50 individuals and tested the hypothesis that these are associated. Pupil diameter and constriction latency significantly correlated with parameters of heart rate variability, but not with those of blood pressure variability. In contrast, relative amplitude significantly correlated with blood pressure variability only. In conclusion, the different branches of the autonomic nervous system examined here are not associated unequivocally but show a distinct pattern of interrelations in healthy subjects. Examinations as described here might add to the diagnosis of autonomic dysfunction and reveal differential patterns in certain disease states.

Relevance of the BONN Risk Index for metabolic monitoring of patients with calcium oxalate urolithiasis: a clinical application study of the Urolizer.

The BONN Risk Index (BRI) successfully determines the calcium oxalate (CaOx) crystallization risk from urine samples. The BRI is based on a standardized crystallization test performed on native urine. A BRI-measuring device, the "Urolizer", has been developed, operating automatically and requiring only a minimum of preparative efforts. In this study, the Urolizer is evaluated regarding its analytical and diagnostic practicability for metaphylaxis control in the framework of the daily routine of a stone surgery. From 51 CaOx recurrent stone-formers, 24 h urines were collected at the beginning and after 3 months of metaphylaxis. As much as 27 patients were indicated to suffer from "mild hypercalciuria", low urinary pH or hypocitraturia, and 24 patients from "hypercalciuria". The former were treated with alkaline citrate (AC), and the latter with hydrochlorothiazide (HCT). Analyses of urines collected before and during treatment, BRI using the Urolizer, and urinalysis-based risk indices were evaluated. In both patient groups, BRI decreased significantly, while metaphylaxis (P<0.001) in the AC group decreased from 1.08 (+/-0.58) to 0.56 (+/-0.39) L(-1) and in the HCT-group from 3.30 (+/-1.15) to 1.60 (+/-0.52) L(-1). In most patients, urinary parameters changed as desired and related risk indices decreased appropriately. The clinical utility of the easy-to-determine BRI is demonstrated. By quantifying the "overall" therapy effect within 15 min, the innovative analysis device may be especially suited for practitioners specializing in urolithiasis treatment.

Analytical precision of the Urolizer for the determination of the BONN-Risk-Index (BRI) for calcium oxalate urolithiasis and evaluation of the influence of 24-h urine storage at moderate temperatures on BRI.

BACKGROUND: Since its first publication in 2000, the BONN-Risk-Index (BRI) has been successfully used to determine the calcium oxalate (CaOx) crystallization risk from urine samples. To date, a BRI-measuring device, the "Urolizer", has been developed, operating automatically and requiring only a minimum of preparation. Two major objectives were pursued: determination of Urolizer precision, and determination of the influence of 24-h urine storage at moderate temperatures on BRI. METHODS: 24-h urine samples from 52 CaOx stone-formers were collected. A total of 37 urine samples were used for the investigation of Urolizer precision by performing six independent BRI determinations in series. In total, 30 samples were taken for additional investigation of urine storability. Each sample was measured thrice: directly after collection, after 24-h storage at T=21 degrees C, and after 24-h cooling at T=4 degrees C. Outcomes were statistically tested for identity with regard to the immediately obtained results. RESULTS: Repeat measurements for evaluation of Urolizer precision revealed statistical identity of data (p-0.05). 24-h storage of urine at both tested temperatures did not significantly affect BRI (p-0.05). CONCLUSIONS: The pilot-run Urolizer shows high analytical reliability. The innovative analysis device may be especially suited for urologists specializing in urolithiasis treatment. The possibility for urine storage at moderate temperatures without loss of analysis quality further demonstrates the applicability of the BRI method.