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This is the second part of an article on the metabolic diagnosis of nephrolithiasis, the first part of which was published in the previous issue of this journal. Here we report on three clinical cases representative of a rational diagnostic workup of nephrolithiasis in specific clinical contexts: secondary hyperuricemia, cystinuria, and primary hyperoxaluria. Nephrolithiasis is one of the most frequent causes of hospitalization in nephrology and urology units in our country and is an important source of discomfort in affected patients. Despite the availability of modern, minimally invasive endourological procedures to remove stones from the urinary tract, prevention of stone recurrences remains an essential strategy. Chemical analysis of stones, whether passed spontaneously or removed surgically, is a crucial step in etiological diagnostics aimed at devising adequate prevention strategies. Modern endoscopic lithotripsy techniques provide complete fragmentation of stones and, compared to extracorporeal shock wave lithotripsy, have the advantage of avoiding painful elimination of fragments through the urinary tract. This means, however, that stone fragments are often unavailable for analysis, thereby depriving the nephrologist of an important tool for diagnosis. As a consequence, metabolic evaluation tends to be the only means of establishing the etiology of stones and preventing their recurrence. We conclude that close collaboration between nephrologists and urologists is a prerequisite for optimizing the diagnosis and treatment of stone disease., non disponibile

Nephrolithiasis is one of the most frequent causes of hospitalization in nephrology and urology units in our country and is an important source of discomfort in affected patients. Despite the availability of modern, minimally invasive endourological procedures to remove stones from the urinary tract, prevention of stone recurrences remains an essential strategy. Chemical analysis of stones, whether passed spontaneously or removed surgically, is a crucial step in etiological diagnostics aimed at devising adequate prevention strategies. Modern endoscopic lithotripsy techniques provide complete fragmentation of stones and, compared to extracorporeal shock wave lithotripsy, have the advantage of avoiding painful elimination of fragments through the urinary tract. This means, however, that stone fragments are often unavailable for analysis, thereby depriving the nephrologist of an important tool for diagnosis. As a consequence, metabolic evaluation tends to be the only means of establishing the etiology of stones and preventing their recurrence. Among patients attending our kidney stone center, we selected five clinical cases representative of a rational diagnostic workup in specific clinical contexts. Two of these nephrolithiasis cases (in a patient with osteoporosis and in a patient with primary hyperparathyroidism) are reported here (Part I); the remaining three will be discussed in the next issue of this journal (Part II)., non disponibile

Many recent papers analyze the association between renal stone disease and other diseases that are typical of industrialized countries. Epidemiology studies from large series indicate that the prevalence of nephrolithiasis is higher among patients with metabolic syndrome, diabetes, and hypertension. Patients with nephrolithiasis also have an increased risk of myocardial infarction and stroke. It has been hypothesized that the common underlying defect could be insulin resistance. This, in turn, alters the urine biochemistry (i.e. more acidic pH and less urine citrate) thereby increasing the propensity of stone forming. In the diabetic rat renal steatosis has been implicated in the reduced production of ammonia, which has been shown to be reversible after PPARγ administration. Furthermore, pioglitazone was shown to be effective in reducing ethylene glycol-induced renal injury. Another significant association concerns gout. Two recent papers report that both calcium and uric acid stone disease are more prevalent among patients with gout. The metabolic derangements found in gouty and non-gouty patients were quite similar. CT imaging in patients with gout indicates that the incidence of nephrolithiasis is underestimated if only based on stone history. Finally, stone episodes may occur many years before the first gouty attack. Another interesting issue is that of a potential adverse effect of calcium and vitamin D supplementation on the risk of stone formation. It has been shown that treated post-menopausal women have a slight but significantly higher risk of forming stones, independently of other interfering variables. From this the recommendation to evaluate the actual benefit of supplementation, even more in the face of its ineffectiveness to prevent fractures in older women. Bariatric surgery is increasingly proposed for managing severe obesity, and in the last few years it has shown a widespread use in the US. Previous procedures of digestive diversion were often com, Molti lavori recenti analizzano l'associazione fra calcolosi renale e altre patologie non trasmissibili tipiche dei paesi industrializzati. I dati epidemiologici, su casistiche ampie, indicano un aumento di incidenza della calcolosi in pazienti con sindrome metabolica, obesità e ipertensione. Viene anche descritto un aumento del rischio di infarto miocardico e di ictus nei litiasici. Si ipotizza che il denominatore comune in queste patologie sia l'aumento della resistenza all'insulina. Questo causa alterazioni della biochimica urinaria, pH più acido e riduzione della citraturia, tali da aumentare il rischio litogeno. Nel ratto diabetico è stata descritta una steatosi renale che riduce l'ammoniogenesi e che è reversibile con una terapia con PPARγ. Il pioglitazone è stato efficace nel ridurre il danno renale indotto nel ratto da etilen glicole. Altra associazione nota è quella fra calcolosi renale e gotta. Due recenti studi documentano un'incidenza della calcolosi calcica e non solo urica nella gotta, con anomalie metaboliche in parte simili a quelle dei pazienti non gottosi. L'indagine TC mostra che l'incidenza di calcolosi è sottostimata nella gotta e, inoltre, la calcolosi, in alcuni pazienti, precede anche di molti anni l'attacco gottoso. Un altro argomento analizza il potenziale effetto che favorisce la calcolosi nelle donne trattate con calcio e vitamina D. Emergono un modesto ma significativo aumento del rischio litogeno indipendente da altre covariabili e un conseguente invito all'attenta valutazione del rapporto rischio/beneficio. La chirurgia bariatrica per la correzione della grave obesità era, in passato, gravata da un elevato rischio di calcolosi renale iperossalurica con quadri anche di ossalosi severa. Negli ultimi anni si sono diffuse tecniche meno litogene come il bendaggio gastrico e il bypass gastrico alla Roux. Iperossaluria e ipocitraturia conseguono a questi interventi e il rischio di calcolosi è di gran lunga inferiore, ma restano segnalazioni i