Relationship of endoscopic lesions of the renal papilla with type of renal stone and 24 h urine analysis.

BACKGROUND: Our purpose was to study the relationship of the 3 different types of endoscopic calcifications of the renal papilla (Randall's plaque, intratubular calcification, papillary crater) with the type of stone and urine analysis. METHODS: This prospective study examined 41 patients (age range: 18 to 80 years) who received retrograde intrarenal surgery (RIRS) for renal lithiasis (mean stone size: 15.3 ± 7.2 mm). The renal papilla injuries were endoscopically classified as Randall's plaque, intratubular calcification, or papillary crater. Calculi were classified as uric acid, calcium oxalate monohydrate (COM; papillary and cavity), calcium oxalate dihydrate (COD), or calcium phosphate (CP). A 24 h urine analysis of calcium, oxalate, citrate, phosphate, and pH was performed in all patients. The relationship of each type of papillary injury with type of stone and urine chemistry was determined. Fisher's exact test and Student's t-test were used to determine the significance of relationships, and a p value below 0.05 was considered significant. RESULTS: The most common injury was tubular calcification (78%), followed by Randall's plaque (58%), and papillary crater (39%). There was no significant relationship of Randall's plaque with type of stone. However, endoscopic intratubular calcification (p = 0.025) and papillary crater (p = 0.041) were more common in patients with COD and CP stones. There were also significant relationships of papillary crater with hypercalciuria (p = 0.036) and hyperoxaluria (p = 0.024), and of Randall's plaque with hypocitraturia (p = 0.005). CONCLUSIONS: There are certain specific relationships between the different types of papillary calcifications that were endoscopically detected with stone chemistry and urine analysis. COD and CP stones were associated with endoscopic tubular calcifications and papillary craters. Hypercalciuria was associated with tubular calcification, and hypocitraturia was associated with Randall's plaque.

Relación entre la percepción del consumo oral de líquidos y el volumen urinario en población sana / Oral fluid intake perception and urine volume in a healthy population

Introducción: el volumen urinario bajo (< 1 ml/kg/h) es el factor etiológico más frecuente en la litiasis renal. Frecuentemente, se asume que los niños que refieren beber mucho tienen una diuresis protectora. En este estudio analizamos el hábito de consumo de líquidos en niños sanos y su relación con el volumen urinario. Metodología: se estudiaron 84 niños, de 5 a 17 años. Se registró la percepción de consumo habitual de líquidos como: "poco", "normal" o "mucho" y los tipos de bebida habitual. Se cuantificó el volumen en orina de 24 h y se relacionó con la percepción de la ingesta de líquidos. Resultados: la ingesta habitual de líquidos fue calificada como "poca" en el 23% de los casos, "normal" en un 56% y "mucha" en un 21%. El 39% de los niños (33/84) presentó una diuresis > 1 ml/kg/h que, por grupos, supone el 38,9% de los que refirieron una ingesta escasa, el 63% de los de consumo "normal" y el 73,7% de los que refirieron ingesta elevada. El 56% de los niños de los grupos de ingesta "normal" y "elevada" mostraron una diuresis < 1 ml/kg/h. Conclusiones: la mayoría de niños mostraron una diuresis por debajo del límite recomendado, incluso entre los que refieren una ingesta "normal" o "elevada" de líquidos. Estos hallazgos hacen visible la necesidad de promover estrategias encaminadas a aumentar el consumo de agua en la población (AU)

Introduction: a low urine volume is a main etiological factor for renal lithiasis (< 1 ml/kg/h). It is commonly assumed that children who report a high fluid intake have a protective urine volume. The purpose of the present study is to assess the habit of fluid intake in healthy schoolchildren and to evaluate its relation with the urinary volume. Methods: eighty-four healthy schoolchildren (5-17 years) were asked to categorize their usual fluid intake amount by choosing one of the three options: "low", "normal" or "high" fluid intake. The usual consumed types of beverage were also recorded. Twenty-four-hour urine volume was measured in each child. The results of the questionnaire were compared to that from the urine samples. Results: a "low" fluid intake was referred by 23% of children, a "normal" fluid intake by 57% and a "high" fluid intake by 21%. Diuresis values > 1 ml/kg/h were observed in 39% of children (that is: 38.9% of the "low intake" group, 63% of the "normal intake" group and 73.7% of the "high intake" group). Among "normal" and "high" intake groups, a urinary output < 1 ml/kg/h was found in 56% of children. Conclusions: a majority of the studied children did not reach the minimum recommended diuresis to prevent urinary lithiasis, even among children who report a high intake of fluids. Strategies aimed at increasing water intake by children population should be highly encouraged (AU)

[Microinfections and kidney lithiasis]. / Microinfecciones y litiasis renal.

OBJECTIVE: 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. METHODS: 1,000 calculi (excluding struvite calculi) were analyzed by macroscopic and microscopic techniques. RESULTS: 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. CONCLUSIONS: 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.

[Types of kidney calculi. Relationship with urinary biochemistry]. / Tipos de cálculos renales. Relación con la bioquímica urinaria.

OBJECTIVE: 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). METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

[Anuria in HIV+ patients treated with indinavir]. / Anuria en pacientes HIV+ tratados con Indinavir.

OBJECTIVE: Two cases of oliguric acute renal failure in HIV+ patients treated with indinavir are described. METHODS: Patient evaluation included blood analysis, urinalysis, abdominal x-rays, renal US and IVP. RESULTS: Both cases resolved with discontinuation of drug therapy, administration of fluids and urine acidification. CONCLUSIONS: 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.

[Urinary lithiasis composed of silica]. / Litiasis urinaria de silice.

We present a case of urinary silica (silicon dioxide) lithiasis in a patient without a background of medication use justifying the formation of this calculus. We review the literature on this type of lithiasis and comment on some aspects of the metabolism of silica connected with urolithiasis.