Stone analysis is not useful in the routine investigation of renal stone disease

The power of desktop scanning electron microscopy with elemental analysis for analyzing urinary stones

The aim of this paper is to present a protocol for the routine morphocompositional study of kidney stones in a clinical setting, and to demonstrate that it is a simple and useful approach that can reliably determine the etiology of all types of kidney stones. Our routine study of kidney stones consists of a combination of stereoscopic microscopy, scanning electron microscopy, and infrared spectroscopy. The usefulness of such a procedure is demonstrated by its application to several illustrating examples. The protocol applied here is reliable and fast, and does not require multiple infrared spectroscopic analyses for most non-homogeneous samples. It also provides the identification of components that are present in very small proportions, the characteristics of internal and external structures, and information about areas with biological structures, such as renal tubules. It should be noted that results are obtained in a relatively short time and with high reliability. The detailed morphocompositional study of a urinary calculus is essential for establishing the diagnosis and etiology and for initiating the treatment of a patient with renal lithiasis, because there is a relationship between the specific characteristics of a stone and the specific etiology of the disease. The increasing number of treatments available for patients with different types of renal calculi makes improvements in diagnosis and determination of stone etiology, such as the procedure described here, more important now than ever.

Determination of urinary stone composition using biochemical analysis of fluid samples taken during ureterorenoscopic laser lithotripsy

PURPOSE

The present study aims to biochemically analyze the fluid samples containing stone dust taken during the perioperative period to determine the role of fluid in the prediction of stones in patients treated with ureterorenoscopic procedures. Our secondary aim is to investigate the role of both fluid analysis and stone analysis in predicting the results of the metabolic analysis.

METHODS

Comparative analyses were performed using fluid samples containing stone dust from 93 patients. Biochemical analysis of fluid containing stone dust was conducted; stone fragments were examined at a separate location using X-ray diffractometry(XRD). Metabolic analysis was performed to patients who provided stone-free status 1 month later. The results of chemical analysis were compared with the results of the XRD analysis.

RESULTS

Patients' stone type was determined with high accuracy using biochemical analysis. Differences were noted in ten patients following biochemical analysis and XRD analysis. Biochemical analysis predicted metabolic disorders in more patients than XRD analysis, particularly for those patients with multiple stone compositions. However, no significant differences between the results of biochemical and XRD analysis methods were found (κ = 0.27; p = 0.002). Moreover, biochemical analysis results revealed metabolic disorders in five patients; these findings were missed by XRD analysis.

CONCLUSION

Biochemical analysis of fluid taken perioperatively during ureterorenoscopic laser lithotripsy to treat urinary system stone disease was found to determine stone composition with high accuracy. Biochemical analysis of fluid samples taken during the perioperative period is, thus, an easy, reliable and cost-effective test to assess stone composition in patients undergoing ureterorenoscopic procedures.

FT-IR analysis of urinary stones: a helpful tool for clinician comparison with the chemical spot test

Background. Kidney stones are a common illness with multifactorial etiopathogenesis. The determination of crystalline and molecular composition and the quantification of all stone components are important to establish the etiology of stones disease but it is often laborious to obtain using the chemical method. The aim of this paper is to compare chemical spot test with FT-IR spectroscopy, for a possible introduction in our laboratory. Methods. We analyzed 48 calculi using Urinary Calculi Analysis kit in accordance with the manufacturer's instructions. The same samples were analyzed by FT-IR using the Perkin Elmer Spectrum One FT-IR Spectrometer. All FT-IR spectra of kidney stones were then computer matched against a library of spectra to generate a report on the various components. Results. On the basis of FT-IR analysis, the 48 calculi were divided into three groups: pure stone, mixed stone, and pure stone with substances in trace. Results of each group were compared with those obtained with chemical spot test. A general disagreement between methods was observed. Conclusions. According to our data, the introduction of the FT-IR technique in clinical chemistry laboratory may be more responsive to clinician expectations.

[Why and how we must analyse urinary calculi]

CONTEXT

There is heterogeneity of criteria on the utility of urinary stone analysis as well as on which is the most suitable methodology. This review presents the analysis of the lithiasis using the morphoconstitutional analysis technique based on the combination of the stereoscopic microscopy (SM) with infrared study (IRS).

SUMMARY OF THE EVIDENCE

There are many techniques to analyze the stone: chemical analysis, electron microscopy, X-ray diffraction, SM and IRS. Reviewing each one of these techniques and through the study of several clinical cases, this review shows the usefulness of stone analysis and the pros and cons of each one of the mentioned techniques. Furthermore, it can be clearly seen how the morphoconstitutional analysis is the one that offers the most useful clinical information to the urologist. In addition, classification of the lithiasis based on this method and its clinical correlation with patients is presented.

CONCLUSIONS

Using the morphoconstitutional study to analyze the stone offers more information than the other techniques and it makes it possible to establish a stone classification of important clinical and diagnostic utility.

ACP Best Practice No 181: Chemical pathology clinical investigation and management of nephrolithiasis

Renal stones have afflicted humans for millennia but there is still no solution to this problem. This review discusses the laboratory and metabolic aspects of the clinical management of patients with renal stones, both primary and secondary in origin. First, non-pharmacological interventions such as increased fluid intake, decreased protein consumption, dietary changes in sodium, calcium, oxalate, potassium, purine, vitamins, and essential fatty acids are considered. Then specific pharmacological treatment to modify urine calcium, oxalate, urate, citrate, and acidity are considered. Finally, more unusual types of stone are examined.

Wet vs. dry chemical analysis of renal stones

Analysis of renal stones may help in elucidating the pathogenesis of nephro-lithiasis. This study compared the use of 2 methods for the analysis of renal stones. One method is qualitative dry 'spot tests' whereas the other is quantitative 'wet chemistry.' In the wet chemistry method, dissolved stone material were analysed using automated chemistry analysers, whereas, the dry method involved spot colour end-point detection. Stones (n = 64) were analysed by both methods. The majority of stones were calcium oxalate as determined by wet chemistry (57.4 per cent) and spot tests (50.0 per cent). Fewer mixed stones were obtained by the wet chemistry method (16.8 per cent) compared with the spot tests method (39.0 per cent), whereas, more uric acid stones were obtained by the wet chemistry method (5.6 per cent) compared with the spot tests method (1.9 per cent). 'Pure' calcium phosphate stones (3.0 per cent) were only obtained by the wet chemistry method. In the wet chemistry method, dissolved stone material did not show significant deterioration on storage for up to 9 days.

Renal stone analysis: is there any clinical value?

It has usually been assumed that the analysis of recovered renal stones should be routinely done. This concept has recently been challenged. Very little work has been done to correlate analytical results with clinical findings and the impact of this information on clinical management. This paper reviews current concepts of stone formation, how this information can be used to interpret stone analysis results and how stone analyses results can be used in clinical-decision-making.

Sodium pentosan polysulphate--a novel inhibitor of urinary risk factors and enzymes in experimental urolithiatic rats

Sodium pentosan polysulphate (SPP) has been shown to inhibit calcium oxalate crystallization in vitro. Here, the effect of SPP was studied on in vivo crystallization. Ammonium oxalate was used as the inducer of calcium oxalate crystallization in rats and the effect of SPP on in vivo crystallization factor is reported. The increased excretions of stone forming constituents associated with urinary marker enzymes are the salient features observed in experimental rats. Sodium pentosan polysulphate administration brought about a significant reduction in urinary stone forming constituents. It also decreased the extent of renal tubular damage as evidenced from the reduced level of marker enzymes in urine. These observations highlight the inhibitory capacity of SPP against in vivo calcium oxalate crystallization.