Urolithiasis:assessment and metabolicmanagement / Lithiase urinaire : bilan et prise en charge métabolique.

Urolithiasis: assessment and metabolic management. Nephrolithiasis is a very common and recurrent disease. A minimal biological assessment is indicated in all patients. A more detailed biological investigation can be required according to the results of the first biological screening, or in case of recurrence, or in first intention depending on the medical history or on the consequences of renal calculi. Stone analysis (morphologic and using infra-red spectrophotometry) is the cornerstone for the understanding of the underlying pathophysiological processes. An appropriate imaging modality should be performed in order to detect urinary tract malformation in case of multiple or recurrent renal calculi. A medical treatment including at least dietary modifications must be prescribed to prevent stone recurrence and the potential risk of chronic kidney disease. Medical and dietary management should be individualized according to each type of stones.

Lithiase urinaire : bilan et prise en charge métabolique. La maladie lithiasique rénale est une pathologie fréquente qui peut récidiver. Une évaluation biologique minimale est indiquée dès sa découverte. Selon ses résultats, ou en cas de récidive, ou en première intention selon le terrain, ou en raison du retentissement de la maladie lithiasique, une exploration biologique plus approfondie est indiquée. Dans tous les cas, l'analyse morpho-constitutionnelle du calcul est indispensable à la compréhension de la physiopathologie du processus lithiasique. Une uropathie malformative doit être recherchée par la réalisation d'une imagerie adaptée en cas de calculs multiples et/ou de récidives. Un traitement médical préventif comportant au minimum des règles diététiques doit être initié en raison du risque de récidive et de maladie rénale chronique. La connaissance de la nature des calculs permettra d'adapter ces mesures préventives.

Quality Assessment of Urinary Stone Analysis: Results of a Multicenter Study of Laboratories in Europe.

After stone removal, accurate analysis of urinary stone composition is the most crucial laboratory diagnostic procedure for the treatment and recurrence prevention in the stone-forming patient. The most common techniques for routine analysis of stones are infrared spectroscopy, X-ray diffraction and chemical analysis. The aim of the present study was to assess the quality of urinary stone analysis of laboratories in Europe. Nine laboratories from eight European countries participated in six quality control surveys for urinary calculi analyses of the Reference Institute for Bioanalytics, Bonn, Germany, between 2010 and 2014. Each participant received the same blinded test samples for stone analysis. A total of 24 samples, comprising pure substances and mixtures of two or three components, were analysed. The evaluation of the quality of the laboratory in the present study was based on the attainment of 75% of the maximum total points, i.e. 99 points. The methods of stone analysis used were infrared spectroscopy (n = 7), chemical analysis (n = 1) and X-ray diffraction (n = 1). In the present study only 56% of the laboratories, four using infrared spectroscopy and one using X-ray diffraction, fulfilled the quality requirements. According to the current standard, chemical analysis is considered to be insufficient for stone analysis, whereas infrared spectroscopy or X-ray diffraction is mandatory. However, the poor results of infrared spectroscopy highlight the importance of equipment, reference spectra and qualification of the staff for an accurate analysis of stone composition. Regular quality control is essential in carrying out routine stone analysis.

Primary prevention of nephrolithiasis is cost-effective for a national healthcare system.

UNLABELLED: Study Type--Therapy (cost-effectiveness meeting) Level of Evidence 2b. What's known on the subject? and What does the study add? One of the major problems with nephrolithiasis is the high rate of recurrence, which can effect up to 50% of patients over a 5-year period. Patients with recurrent stones are recommended to increase fluid intake based on prospective studies that show a reduction in recurrence rates in patients who intake a high volume of water. Strategies to reduce stones in recurrent stone formers are quite effective with a >50% risk reduction with increased fluid intake alone. Unfortunately, despite a high societal cost and morbidity, there are no prospective studies evaluating the benefit of fluid intake to prevent stone disease in subjects without a prior history of stone but at risk for stones. The budget impact analyses show that prevention of nephrolithiasis can have a significant cost savings for a payer in a healthcare system and reduce the stone burden significantly. Future studies will need to assess the feasibility and effectiveness of such an approach in a population. OBJECTIVE: • To evaluate the impact of primary prevention of stones using a strategy of increased fluid intake. SUBJECTS AND METHODS: • A Markov model was constructed and analysed using Excel to calculate and compare the costs and outcomes for a virtual cohort of subjects with low vs high water intake. • A literature search was used to formulate assumptions for the model including an annual incidence of urolithiasis of 0.032%, annual risk of stone recurrence of 14.4% and 40% risk reduction in subjects with high water intake. • Costs were based on resource utilisation from the Delphi panel and official price lists in France. • Outcomes were based on payer perspective and included direct and indirect costs and loss of work. RESULTS: • The base-case analysis found total cost of urolithiasis is €4267 with direct costs of €2767, including cost of treatment and complications. The annual budget impact for stone disease based on 65 million inhabitants is €590 million for the payer. • The use of high water intake by 100% of the population results in annual cost savings of €273 million and 9265 fewer stones. Even if only 25% of the population is compliant, there is still a cost saving of €68 million and 2316 stones. • The model was evaluated to determine the impact of varying the assumptions by ±10%. For example, when the incidence of stone disease is increased or decreased by 10% then the mean (range) baseline cost will change by €59(531-649) million for the payer and savings will either increase or decrease by €27 (246-300) million. • The largest impact on cost savings occurs when varying risk reduction of water by 10% resulting in either a mean (range) increase or decrease by €35 (238-308) million. • Varying cost of stone management by 10% has an impact of ±€17 million. Varying other factors such as stone recurrence by 10% has only an impact of ±€9 million and varying risk of chronic kidney disease ±€1 million, as they affect only a portion of the population. CONCLUSIONS: • The budget impact analyses show that prevention of nephrolithiasis can have a significant cost savings for a payer in a healthcare system and reduce the stone burden significantly. • Future studies will need to assess the feasibility and effectiveness of such an approach in a population.

Imaging-based assessment of the mineral composition of urinary stones: an in vitro study of the combination of hounsfield unit measurement in noncontrast helical computerized tomography and the twinkling artifact in color Doppler ultrasound.

We evaluated the value of combining noncontrast helical computerized tomography (NCHCT) and color Doppler ultrasound in the assessment of the composition of urinary stones. In vitro, we studied 120 stones of known composition, that separate into the five main types: 18 calcium oxalate monohydrate (COM) stones, 41 calcium oxalate dihydrate (COD) stones, 24 uric acid stones, 25 calcium phosphate stones and 12 cystine calculi. Stones were characterized in terms of their Hounsfield density (HU) in NCHCT and the presence of a twinkling artifact (TA) in color Doppler ultrasound. There were statistically significant HU differences between calcium and non-calcium stones (p < 0.001), calcium oxalate stones and calcium phosphate stones (p < 0.001) and uric acid stones and cystine calculi (p < 0.001) but not between COM and COD stones (p = 0.786). Hence, the HU was a predictive factor of the composition of all types of stones, other than for COM and COD stones within the calcium oxalate class (p > 0.05). We found that the TA does not enable differentiation between calcium and non-calcium stones (p > 0.999), calcium oxalate stones and calcium phosphate stones (p = 0.15), or uric acid stones and cystine calculi (p = 0.079). However, it did reveal a significant difference between COM and COD stones (p = 0.002). The absence of a TA is a predictive factor for the presence of COM stones (p = 0.008). Hence, the association of NCHCT and Doppler enables the accurate classification of the five types of stones in vitro.

Calcifications in human osteoarthritic articular cartilage: ex vivo assessment of calcium compounds using XANES spectroscopy.

Calcium (Ca(2+))-containing crystals (CCs), including basic Ca(2+) phosphate (BCP) and Ca(2+) pyrophosphate dihydrate (CPPD) crystals, are associated with severe forms of osteoarthritis (OA). Growing evidence supports a role for abnormal articular cartilage mineralization in the pathogenesis of OA. However, the role of Ca(2+) compounds in this mineralization process remains poorly understood. Six patients, who underwent total knee joint replacement for primary OA, have been considered in this study. Cartilage from femoral condyles and tibial plateaus in the medial and lateral compartments was collected as 1 mm-thick slices cut tangentially to the articular surface. First, CCs presence and biochemical composition were assessed using Fourier transform infrared spectroscopy (FT-IR). Next, Ca(2+) compound biochemical form was further assessed using X-ray absorption spectroscopy (XAS) performed at the Ca(2+) K-absorption edge. Overall, 12 cartilage samples were assessed. Using FT-IR, BCP and CPPD crystals were detected in four and three out of 12 samples, respectively. Ca(2+) compound biochemical forms differed between areas with versus without CCs, when compared using XAS. The complete set of data shows that XANES spectroscopy can be used to accurately characterize sparse CCs in human OA cartilage. It is found that Ca(2+) compounds differ between calcified and non-calcified cartilage areas. In calcified areas they appear to be mainly involved in calcifications, namely Ca(2+) crystals.

Drug-induced renal calculi: epidemiology, prevention and management.

Drug-induced calculi represent 1-2% of all renal calculi. The drugs reported to produce calculi formation may be divided into two groups. The first one includes poorly soluble drugs with high urine excretion that favours crystallisation in the urine. Among poorly soluble molecules, triamterene was the leading cause of drug-containing urinary calculi in the 1970s, and it is still currently responsible for a significant number of calculi. In the last decade, drugs used for the treatment of HIV-infected patients, namely indinavir and sulfadiazine, have become the most frequent cause of drug-containing urinary calculi. Besides these drugs, about twenty other molecules may induce nephrolithiasis in patients receiving long-term treatment or high doses. Calculi analysis by physical methods, including infrared spectroscopy or x-ray diffraction, is needed to demonstrate the presence of the drug or its metabolites within the calculi. The second group includes drugs that provoke urinary calculi as a consequence of their metabolic effects. Here, diagnosis relies on careful clinical inquiry because physical methods are ineffective to differentiate between urinary calculi induced by the metabolic effects of a drug and common metabolic calculi. The incidence of such calculi, especially those resulting from calcium/vitamin D supplementation, is probably underestimated. Although drug-induced urinary calculi most often complicate high-dose, long-duration drug treatments, there also exist specific patient risk factors in relation to urine pH, urine output and other parameters, which provide a basis for preventive or curative treatment of calculi. Better awareness of the possible occurrence of lithogenic complications, preventive measures based on drug solubility characteristics and close surveillance of patients on long-term treatment with drugs with lithogenic potential, especially those with a history of urolithiasis, should reduce the incidence of drug-induced nephrolithiasis.