Physiological effects of slow release potassium phosphate for absorptive hypercalciuria: a randomized double-blind trial

Metabolic diagnosis and medical prevention of calcium nephrolithiasis and its systemic manifestations: a consensus statement

BACKGROUND

Recently published guidelines on the medical management of renal stone disease did not address relevant topics in the field of idiopathic calcium nephrolithiasis, which are important also for clinical research.

DESIGN

A steering committee identified 27 questions, which were proposed to a faculty of 44 experts in nephrolithiasis and allied fields. A systematic review of the literature was conducted and 5216 potentially relevant articles were selected; from these, 407 articles were deemed to provide useful scientific information. The Faculty, divided into working groups, analysed the relevant literature. Preliminary statements developed by each group were exhaustively discussed in plenary sessions and approved.

RESULTS

Statements were developed to inform clinicians on the identification of secondary forms of calcium nephrolithiasis and systemic complications; on the definition of idiopathic calcium nephrolithiasis; on the use of urinary tests of crystallization and of surgical observations during stone treatment in the management of these patients; on the identification of patients warranting preventive measures; on the role of fluid and nutritional measures and of drugs to prevent recurrent episodes of stones; and finally, on the cooperation between the urologist and nephrologist in the renal stone patients.

CONCLUSIONS

This document has addressed idiopathic calcium nephrolithiasis from the perspective of a disease that can associate with systemic disorders, emphasizing the interplay needed between urologists and nephrologists. It is complementary to the American Urological Association and European Association of Urology guidelines. Future areas for research are identified.

Preventive fluid and dietary therapy for urolithiasis: An appraisal of strength, controversies and lacunae of current literature

Regulation of fluid and dietary intake habits is essential in comprehensive preventive management of urolithiasis. However, despite large body of epidemiological database, there is dearth of good quality prospective interventional studies in this regard. Often there is conflict in pathophysiological basis and actual clinical outcome. We describe conflicts, controversies and lacunae in current literature in fluid and dietary modifications in prevention of urolithiasis. Adequate fluid intake is the most important conservative strategy in urolithiasis-prevention; its positive effects are seen even at low volumes. Of the citrus, orange provides the most favorable pH changes in the urine, equivalent to therapeutic alkaline citrates. Despite being richest source of citrate, lemon does not increase pH significant due to its acidic nature. Fructose, animal proteins and fats are implicated in contributing to obesity, which is an established risk factor for urolithiasis. Fructose and proteins also contribute to lithogenecity of urine directly. Sodium restriction is commonly advised since natriuresis is associated with calciuresis. Calcium restriction is not advisable for urolithiasis prevention. Adequate calcium intake is beneficial if taken with food since it reduces absorption of dietary oxalate. Increasing dietary fiber does not protect against urolithiasis. Evidence for pyridoxine and magnesium is not robust. There is no prospective interventional study evaluating effect of many dietary elements, including citrus juices, carbohydrate, fat, dietary fiber, sodium, etc. Due to lack of good-quality prospective interventional trials it is essential to test the findings of pathophysiological understanding and epidemiological evidence. Role of probiotics and phytoceuticals needs special attention for future research.

Pharmacological interventions for preventing complications in idiopathic hypercalciuria

BACKGROUND

Idiopathic hypercalciuria is an inherited metabolic abnormality characterised by excessive amounts of calcium excreted into the urine in patients with normal serum levels of calcium. The morbidity of hypercalciuria is related to kidney stone disease and bone demineralization. In children, hypercalciuria can cause recurrent haematuria, frequency-dysuria syndrome, urinary tract infection and abdominal and lumbar pain. Several pharmacological treatments have been described that can decrease the levels of urinary calcium or its index of urinary crystallization.

OBJECTIVES

To assess the benefits and harms of pharmacological interventions for preventing complications and decreasing urological symptoms in patients with idiopathic hypercalciuria.

SEARCH STRATEGY

We searched MEDLINE, EMBASE, the Cochrane Renal Group's specialised register, the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library), handsearched relevant conference proceedings and reference lists of articles.

SELECTION CRITERIA

All randomised controlled trials (RCTs) and quasi-RCTS that compared any pharmacological intervention for preventing complications in idiopathic hypercalciuria, with placebo, other pharmacological intervention or a different administration mode or dose of the same treatment given for a minimum duration of four months and had a follow-up period of at least six months.

DATA COLLECTION AND ANALYSIS

Four authors assessed the studies for inclusion and extracted the data. Disagreements were resolved through discussion. Results were expressed as risk ratios (RR) with 95% confidence intervals (CI) or mean difference (MD).

MAIN RESULTS

Five studies (316 adult patients) were included. Four compared thiazides with standard treatment (periodic clinical follow-up and increased water intake) or specific dietary recommendations and one analysed the effect of thiazide plus a neutral potassium salt. There was a significant decrease in the number of new stone recurrences in those treated with thiazides (RR 1.61, 95% CI 1.33 to 1.96), although the follow-up periods varied. The stone formation rate also showed a statistically significant decrease in the patients treated with diuretics (MD -0.18, 95% CI -0.30 to -0.06). Thiazides plus potassium salts significantly decreased calciuria and vitamin D levels.

AUTHORS' CONCLUSIONS

There is some evidence that in patients with idiopathic hypercalciuria and recurrent stones, the addition of thiazides to a normal or modified diet for short to long periods (five months to three years) reduced the number of stone recurrences and decreased the stone formation rate. Thiazides and neutral potassium phosphate decreased calciuria in symptomatic patients with idiopathic hypercalciuria. There were no studies investigating the effect of pharmacological treatment on other clinical complications or asymptomatic idiopathic hypercalciuria.