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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.

Dietary Questionnaire used to obtain the information on the consumption of different food groups (Legumes, Nuts, Whole grain foods, Fruits and vegetables, Chocolate, Sweet foods and refined sugars). (DOC 45 kb)

Hydrodynamics of the CD. (DOCX 13 kb)

Used expressions. (DOCX 11 kb)

The transit time of particle through the tubule. (DOCX 13 kb)

Objective To perform a multivariate statistical analysis of epidemiological, clinical and biochemical factors that make it possible to identify the variables that can independently predict the course of renal lithiasis, thus defining a group at risk of worse evolution. Materials and methods A retrospective, descriptive and analytic study was in a cohort of 248 patients with kidney stones treated in our center from 2003 to 2007. A univariate analysis (Chi-square) and a multivariate analysis (regression model) of possible epidemiological predictive factors (age and gender), clinical data of stones (number, localization, size and bilaterality) and biochemical factors (urinary composition and stone composition) were analyzed. Results Based on a mean follow-up of 60 months (95% CI: 52.5–67.4) we observed a global persistence of kidney stones in 121 patients (48.8%) and 127 patients being stone-free (51.2%). The univariate analysis describes the following variables as being associated to greater persistence of lithiasis: age, number of stones, calyceal localization and bilaterality, urinary biochemical composition, and stone biochemical composition. In regards to all of the above variables, only age less than 47 years, bilaterality, stone localization and chemical composition of the lithiasis (oxalate calcium dehydrated) were significantly associated to a major risk of persistence of kidney stones. Conclusion There is a high persistence rate of kidney stones. Patient age inferior to 47 year, calyceal localization, bilaterality, and biochemical composition of stones (oxalate calcium dihydrate) are independent factors associated to higher persistence rate of kidney stones. These factors indicate a risk group with a worse clinical prognosis in which we should reconsider more individualized diagnostic and therapeutic strategies.

To perform a multivariate statistical analysis of epidemiological, clinical and biochemical factors that make it possible to identify the variables that can independently predict the course of renal lithiasis, thus defining a group at risk of worse evolution.A retrospective, descriptive and analytic study was in a cohort of 248 patients with kidney stones treated in our center from 2003 to 2007. A univariate (chi-square) and multivariate analysis (regression model) of possible epidemiological predictive factors (age, gender), clinical data of stones (number, localization, size and bilaterality) and biochemical factors (urinary composition, stone composition) were analyzed.Based on a mean follow-up of 60 months (95% CI: 52.5-67.4) we observed a global persistence of kidney stones in 121 patients (48.8%), 127 patients being stone-free (51.2%). The univariate analysis describes the following variables as being associated to greater persistence of lithiasis: age, number of stones, calyceal localization and bilaterality, urinary biochemical composition, and stone biochemical composition. In regards to all of the above variables, only age less than 47 years, bilaterality, stone localization and chemical composition of the lithiasis (oxalate calcium dehydrated) were significantly associated to a major risk of persistence of kidney stones.There is a high persistence rate of kidney stones. Patient age inferior to 47 year, calyceal localization, bilaterality, and biochemical composition of stones (oxalate calcium dihydrate) are independent factors associated to higher persistence rate of kidney stones. These factors indicate a risk group with a worse clinical prognosis in which we should reconsider more individualized diagnostic and therapeutic strategies.

To present a simple classification of the most frequent renal calculi that relates each type of calculus with the main possible etiologic factors linked to its formation (mainly urinary biochemical parameters).The macro, microstructure and composition of 2,500 renal calculi were studied by appropriate combination of stereoscopic microscopy, IR spectroscopy and scanning electron microscopy + X-ray microanalysis. The information obtained were related with the main urinary biochemical parameters, determined by conventional analytical procedures.Ten main categories of renal stones, covering over 95% of all conceivable calculi, are distinguished based on their composition and structure. Etiologic factors, mainly urinary biochemical parameters, leading to the formation of stone of every category are specified.From the detailed study of the renal calculus important etiologic factors can be deduced. Such information complements and confirms the urinary biochemical studies. As a consequence, the corresponding treatment can be better established.

The existence of microinfections produced by bacteria of a very small size (nanobacteria) could be a risk factor for stone formation. The results of a study to detect the presence of nanobacteria in calculi are presented.1,000 calculi (excluding struvite calculi) were analyzed by macroscopic and microscopic techniques.Microorganisms were detected in only 5 calculi (0.5%). All these calculi had developed in cavities with low urodynamic efficacy. The microorganisms were located in the center of the calculus and the main component was calcium oxalate monohydrate or uric acid. Ammonium urate/sodium urate were frequently found to be a minor component in the center of the calculus. The only common biochemical urinary alteration observed in these patients was a urinary pH below 5.5; conventional urine cultures were always negative.Our findings demonstrate that these bacteria can play an important role in the development of calculus by inducing the formation of heterogeneous nucleants of calcium oxalate and uric acid. According to our results, however, this mechanisms is not common and would also be associated to other lithogenic risk factors. It is important to underscore that the majority of patients suffered from stomach ulcers and/or gingivitis which are conditions that could be induced by the same type of microorganisms. Therefore, it can be deduced that similar bacterial factors might be involved in pathologies that have as yet not been related. Further studies are warranted to clearly identify these bacteria.

A concise account of formation mechanisms of attached (papillary) and unattached renal stones is presented. Urinary conditions prevailing at least during the stone forming period are indicated. Ten main categories of renal stones, covering over 95% of all conceivable calculi, are distinguished based on their composition and structure. Aetiologic factors leading to stone formation of every category are specified and general outlines of recommended treatment procedures indicated.

Two cases of oliguric acute renal failure in HIV+ patients treated with indinavir are described.Patient evaluation included blood analysis, urinalysis, abdominal x-rays, renal US and IVP.Both cases resolved with discontinuation of drug therapy, administration of fluids and urine acidification.Severe acute renal failure is an uncommon complication in HIV+ patients treated with indinavir. This drug has a great tendency to precipitate in urine. The severity of the crystalluria depends on the drug dose and urinary pH, and can cause tubulointerstitial nephritis and urinary calculi with obstruction of the urinary tract.

Calcium renal lithiasis formation depends on the balance between thermodynamic (supersaturation) and kinetic (inhibitors, nucleants) factors. In this paper, the importance of both groups was evaluated using (a) the complete urine analysis data obtained from 32 healthy volunteers and 141 active stone-formers, and (b) a comprehensive computer model to calculate the supersaturation values of calcium oxalate monohydrate, hydroxyapatite and brushite in each urine sample. The results of this evaluation were used to assess the possible effectiveness of a given pharmacological treatment.

This is a comparative study of the effects of phytate and pyrophosphate and other polyphosphates on the crystallization of hydroxyapatite and brushite, the most frequent calcium phosphates involved in calcium oxalate urolithiasis. Brushite and hydroxyapatite crystal formation was studied in synthetic urine, through kinetic-turbidimetric measurements that allowed evaluation of the inhibitory effects on crystallization of insoluble salts. The effectiveness in preventing brushite crystallization decreases in the sequence phytatepolyphosphateEDTPOetidronatepyrophosphatetriphosphatemedronate; whereas the order of effectiveness in preventing hydroxyapatite crystallization was EDTPOetidronate = pyrophosphatetriphosphatemedronatepolyphosphatephytate. Phytate, a natural inhibitor in urine, most effectively blocked brushite precipitation (1.21x10(-5) M prevented crystallization during time periods of at least 1 h), and pyrophosphate was the natural inhibitor that most effectively blocked hydroxyapatite precipitation (2.87x10(-6) M prevented crystallization during time periods of at least 1 h). This demonstrates that low excretion of these substances would pose a risk of renal lithiasis.

The extraordinary capacity of phytate (myo-inositol hexaphosphate), a substance present in blood, urine, interstitial and intracellular fluids, to inhibit crystallization of calcium salts (oxalate and phosphate) is discussed. Its role in preventing calcium renal stone formation is specifically presented and discussed. "In vitro" and "in vivo" experiments, as well as clinical studies clearly demonstrated that phytate plays an important role as a crystallization inhibitor of calcium salts in biological fluids and becomes a clear alternative in the treatment of calcium oxalate renal lithiasis.

The crystallization of indinavir in synthetic urine at different pH values and indinavir concentrations was kinetically studied. It was found that precipitation time notably decreases at urinary pH values above 6.0. The effects of some products as potential crystallization inhibitors were studied. Some natural saponins such as escin and glycyrrhizic acid provoked a notable increase in the precipitation time of indinavir, this pointing out their possible use to prevent renal tubular solid deposition.

Possible effects of crystal agglomeration on the early stages of calcium oxalate papillar stone formation are evaluated. The collecting ducts are filled with liquid that flows laminarly as established through hydrodynamical and physicochemical considerations. Under such conditions, agglomeration due to laminar shear forces proceeds. Agglomeration of calcium oxalate monohydrate crystals present in urine at a concentration typical for clinically observed crystalluria cannot result in the formation of a particle sufficiently large enough to be retained in the Bellini's duct and become a papillar stone nidus (nucleus). Formation of such an aggregate during the passage time of urine through the duct requires an unrealistically high concentration of crystals in urine, one that exceeds the normal content of urinary oxalate by several orders of magnitude. Aggregates obstructing the Bellini's duct as assumed in the free particle theory cannot represent a major factor in stone formation. This conclusion is corroborated by experimental results and other observations.

A scanning electron microscopy study of the ultrastructure of 18 calcium oxalate monohydrate papillary calculi was performed with the purpose of establishing the main steps in calculus formation. It is concluded that these calculi originate in a "core" located near the central part of the calculus. Significant quantities of organic matter as well as calcium phosphates can be found in the "core" and at the surface of adhesion to the papilla and, in some cases, fibers and calcified tubules can also be found in the contact zone. In no case did this material affect the crystalline structure of the calculi, indicating that its formation follows the calculus genesis. The study of the compact columnar zone revealed that its formation starts in a practically continuous surface formed by organic matter and crystals that surround the core. This layer favors the growth of oriented calcium oxalate monohydrate crystals upon it. Based on these observations, a feasible mechanism of papillary calcium oxalate monohydrate calculus formation is proposed.

The effect of natural admixtures occurring in human urine (citrate, pyrophosphate and glycosaminoglycans) on the precipitation of stone-forming compounds was studied. Experiments were carried out under conditions closely simulating the early stages of renal stone formation. Among the studied admixtures, citrate was determined as the most effective substance preventing the phosphate particle formation. Indeed, in the presence of citrate, some calcium oxalate monohydrate crystals were found. Pyrophosphate induced the formation of calcium oxalate dihydrate crystals. Phosphate crystals appeared at pH 6 and never at pH 5. The easy formation of phosphate particles supports the hypothesis that these crystals represent a very important heterogeneous nucleus-initiating oxalocalcic calculus formation in the kidney. Reported results also indicated uric acid as a significant heterogeneous nucleus of calcium oxalate monohydrate crystals at urinary pH equal or lower than 5 and the important role of bacteria in increasing the organic detritus deposited on the solid surfaces.

Based on reconsideration of the contemporary knowledge on calcium oxalate urolithiasis a feasible mechanism of calculi generation is suggested. Experimental findings and clinical aspects supporting the suggested mechanism are presented. The ways of urolithiasis treatment and areas of future research are indicated.

A study was made of the Tc-toluene-3,4-dithiol complexes obtained in basic media and different conditions. By adequate control of these conditions it seems that technetium can be found in one of the following oxidation states: III, IV or V. The results obtained are compared with those obtained from the Tc-dimercatosuccinic acid system. Formation of such complexes can be used to separate technetium from other elements which frequently accompany it.

The extraction of the ionic species formed between two reduced Tc–SCN anionic complexes and trioctylmethyl ammonium cation has been studied spectrophotometrically in both oxygenated and deoxygenated media. The distribution ratio for each reduced complex has been determined as a function of tin(II) and Adogen 464 concentrations. The results indicate that, depending on the concentration of the Sn(II) reducing agent, a red Tc(IV) or a yellow Tc(III) complex can be formed.

A kinetic-fluorimetric method for determination of traces of selenium (0.01–0.4 ppm) is described. It is based on the fact that the reducing power of alkali sulfides can be considerably enhanced by the addition of elemental selenium. The experimental variables and interferences have been studied. The selenium quantities are estimated in diverse environmental samples.

Kinetic methods for palladium (0.1–0.8 mg l−1) and nickel (0.1−0.7 mg l−1) are based, respectively, on the uncatalyzed bromate oxidation of 2,2′-dipyidylketone hydrazone (DPKH) in acidic media and of dipyridylglyoxal hydrazone (DPDKH) in basic media, to yield fluorescent products. Complexation of DPKH and DPDKH by Pd(II) and Ni(II), respectively, causes a decrease in ligand concentration and thus in reaction rate, which can be related to the concentration of metal. The method for palladium is relatively free from interferences.

A new spectrofluorimetric method for the determination of gold using bipyridylglyoxal diphenylhydrazone as reagent, has been developped. The interferences of foreign ions are also determined.

Interest aroused towards pyrophosphate as a possible inhibitor in calcium oxalate and phosphate lithiasis. A procedure for the quantitative determination of pyrophosphate in urine suitable for use in clinical laboratories is described. The reproducibility of the method was assessed by within-run and between-run reproducibility studies and the accuracy of the method was obtained by determining the amount of pyrophosphate recovered in urine samples. The present study compares the pyrophosphate excretion and concentration between a control group and a calcium oxalate stone former group.