Urinary stone disease in Syrian children.

BACKGROUND: Pediatric urinary stone disease (USD) is a costly medical problem. This study aims to assess the clinical characteristics and outcomes of common and rare causes of pediatric USD. METHODS: A retrospective descriptive cohort study included all children < 13 years of age with confirmed USD admitted to the Children's University Hospital in Damascus, Syria, from January 2013 to December 2019. The study sample was divided into two groups based on etiologies: common and rare causes groups. RESULTS: We evaluated 235 patients; 147 of them were males, and the male-to-female ratio was 1.7:1. The common causes group consisted of 203 patients (mean age 3.52 ± 3.66 years) and mainly included metabolic disorders (45.5%) and anatomical abnormalities (22.3%), while the rare causes group included 32 cases (mean age 4.93 ± 4.08 years), 12 patients with uric acid stones (37.5%), 7 patients with cystinuria (21.9%), and primary hyperoxaluria in 5 patients (15.6%). In addition, 39.6% of study patients were born to consanguineous marriages. Sixty-two patients developed AKI, and eleven patients had chronic kidney disease (CKD). Patients with rare causes were more likely to have AKI, CKD, bilateral stones, and recurrent stones (P-value < 0.05). Stone analysis was performed on 83 patients, and the main stone types were calcium oxalate (34.9%), uric acid (14.4%), and struvite stones (12%). Surgery was the most performed treatment in 101 patients (56.7%). CONCLUSION: Patients with rare causes of pediatric USD are at a higher risk for severe complications and require early diagnosis and management. The high rate of uric acid stones in our society requires further evaluation for possible underlying causes. A higher resolution version of the Graphical abstract is available as Supplementary information.

Risk of urinary stone formation associated to proton pump inhibitors: A systematic review and metanalysis.

OBJECTIVE: Proton pump inhibitors are widely used as treatment of acid-related disorders. They are considered safe although their long-term use has been associated with some adverse effects including an increased propensity for urinary calculi formation. The aim of this study was to systematically review available data from studies evaluating the association of PPIs and nephrolithiasis. MATERIALS AND METHODS: We searched two electronic databases (PubMed and EMBASE) for cohort studies or case-control studies evaluating the relationship between treatment with proton pump inhibitors and the risk of stone formation published up to 31 October 2022. The overall association of PPIs and urinary calculi was analyzed using a random effects model (RevMan5). The quality of the included studies was assessed using the Newcastle-Ottawa Quality Assessment Scale. RESULTS: A total of 550 studies were retrieved; 7 were selected by title and abstract screening; after removal of duplicates, 4 records were evaluated by full-text examination. An additional study was retrieved by handsearching the references included in screened studies. In the unadjusted analysis, the odds of urinary calculi were greater in subjects taking PPIs compared to controls (unadjusted OR = 2.10, 95% CI 1.74-2.52, p < 0.00001). The pooled odds ratio of two case-control studies confirmed that use of PPIs increased the odds of urinary calculi compared with non-use (OR 2.44, 95% CI 2.29 to 2.61). Pooled analysis of three cohort studies evaluating incident nephrolithiasis showed an overall hazard ratio estimate of 1.34 (95% CI = 1.28-1.40). One study found lower urinary citrate and urinary magnesium levels in subjects exposed to PPIs. The Newcastle-Ottawa Quality Assessment Scale scores ranged between 6 and 8. CONCLUSIONS: PPIs showed an association with urinary calculi in patients included in the studies included in this review. If these data will be confirmed in adequately powered randomized trials, clinicians may consider limiting the long-term use of PPIs, to avoid unnecessary prolongation of treatment. Urinary magnesium and citrate should be evaluated in renal stone forming patients taking PPIs to supplement their intake when requested.

May a comprehensive mineralogical study of a jackstone calculus and some other human bladder stones unveil health and environmental implications?

This paper represents the first result of an active collaboration between the University of Sannio and the San Pio Hospital (Benevento, Italy), started in the 2018, that aims to a detailed mineralogical investigation of urinary stones of patients from Campania region. Herein, selected human bladder stones have been deeply characterized for clinical purposes and environmental biomonitoring, focusing on the importance to evaluate the concentration and distribution of undesired trace elements by means of microscopic techniques in the place of conventional wet chemical analyses. A rare bladder stone with a sea-urchin appearance, known as jackstone calculus, were also investigated (along with bladder stones made of uric acid and brushite) by means a comprehensive analytical approach, including Synchrotron X-ray Diffraction and Simultaneous Thermal Analyses. Main clinical assumptions were inferred according to the morpho-constitutional classification of bladder stones and information about patient's medical history and lifestyle. In most of the analyzed uroliths, undesired trace elements such as copper, cadmium, lead, chromium, mercury and arsenic have been detected and generally attributable to environmental pollution or contaminated food. Simultaneous occurrence of selenium and mercury should denote a methylmercury detoxification process, probably leading to the formation of a very rare HgSe compound known as tiemannite.

Association between Recreational Physical Activity and the Risk of Upper Urinary Calculi.

OBJECTIVE: Upper urinary calculi (UUC) is considered to be a comprehensive disease associated with many risk factors, but the role of physical activity (PA) is undefined. Here, we conducted a cross-sectional study to investigate this relationship in Asian populations. MATERIALS AND METHODS: Patients diagnosed with UUC were the subjects of study and those who participated in a health examination in local medical center were included as controls. Information was collected through the same standard questionnaire. A metabolic equivalent score (METs) was measured for each kind of activity. OR of UUC in categories of PA were determined by logistic regression. RESULTS: A total of 1,782 controls and 1,517 cases were enrolled. People who took higher PA (5-9.9, 10-19.9, 20-29.9 and >30 METs/wk) weekly were associated with lower risks of UUC than those took lower PA (<4.9 METs/wk) after adjusting for age, ethnicity, body mass index, systolic blood pressure, water intake, history of gout, history of diabetes mellitus, history of supplemental calcium use and history of hypertension (adjusted OR 0.11, 0.32, 0.24, 0.34; 95% CI 0.08-0.15, 0.23-0.43, 0.15-0.40, 0.22-0.53, respectively; p value <0.001). CONCLUSIONS: In our cross-sectional study, PA was associated with UUC.

[Urinary calculi and infection]. / Calcolosi urinaria e infezione.

Infection urinary stones resulting from urease-producing bacteria are composed by struvite and/or carbonate apatite. Bacterial urease splits urea and promotes the formation of ammonia and carbon dioxide leading to urine alkalinization and formation of phosphate salts. Proteus species are urease-producers, whereas a limited number of strains of other Gram negative and positive species may produce urease. Ureaplasma urealyticum and Corynebacterium urealyticum are urease-producers that are not isolated by conventional urine cultures, but require specific tests for identification. Primary treatment requires surgical removal of stones as complete as possible. Extracorporeal and endoscopic treatments are usually preferred, while open surgery is actually limited to few selected cases. Residual stones or fragments should be treated by chemolysis via ureteral catheter or nephrostomy or administration of citrate salts in order to achieve a stone-free renal unit. Postoperatively, recurrent urinary tract infection should be treated with appropriate antibiotic treatment although long-term antibiotic prophylaxis can cause resistance. Urinary acidification has been proposed for the prophylaxis of infection stones, but long-term acidification is difficult to achieve in urine infected by urease-producing bacteria. Urease inhibitors lead to prevention and/or dissolution of stones and encrustations in patients with infection by urea-splitting bacteria, but their use is limited by their toxicity. The administration of citrate salts involves an increase of the value of nucleation pH (pHn), that is the pH value at which calcium and magnesium phosphate crystallization occurs, in a greater way than the corresponding increase in the urinary pH due to its alkalinizing effect and resulting in a reduction of the risk of struvite crystallization. In conclusion prevention of the recurrence of infection stones can be achieved by an integrated approach tailored on the single patient. Complete clearance of the stone must be achieved by primary surgical procedure and residual fragments should be extensively treated. In the case of persistent infection, conservative measures, such as acidification and urease inhibitors or citrate administration, should be adopted to minimize its effect on urinary saturation with respect to struvite.

Health risks and benefits from calcium and vitamin D supplementation: Women's Health Initiative clinical trial and cohort study.

SUMMARY: The Women's Health Initiative (WHI) double-blind, placebo-controlled clinical trial randomly assigned 36,282 postmenopausal women in the U.S. to 1,000 mg elemental calcium carbonate plus 400 IU of vitamin D(3) daily or placebo, with average intervention period of 7.0 years. The trial was designed to test whether calcium plus vitamin D supplementation in a population in which the use of these supplements was widespread would reduce hip fracture, and secondarily, total fracture and colorectal cancer. INTRODUCTION: This study further examines the health benefits and risks of calcium and vitamin D supplementation using WHI data, with emphasis on fractures, cardiovascular disease, cancer, and total mortality. METHODS: WHI calcium and vitamin D randomized clinical trial (CT) data through the end of the intervention period were further analyzed with emphasis on treatment effects in relation to duration of supplementation, and these data were contrasted and combined with corresponding data from the WHI prospective observational study (OS). RESULTS: Among women not taking personal calcium or vitamin D supplements at baseline, the hazard ratio [HR] for hip fracture occurrence in the CT following 5 or more years of calcium and vitamin D supplementation versus placebo was 0.62 (95 % confidence interval (CI), 0.38-1.00). In combined analyses of CT and OS data, the corresponding HR was 0.65 (95 % CI, 0.44-0.98). Supplementation effects were not apparent on the risks of myocardial infarction, coronary heart disease, total heart disease, stroke, overall cardiovascular disease, colorectal cancer, or total mortality, while evidence for a reduction in breast cancer risk and total invasive cancer risk among calcium plus vitamin D users was only suggestive. CONCLUSION: Though based primarily on a subset analysis, long-term use of calcium and vitamin D appears to confer a reduction that may be substantial in the risk of hip fracture among postmenopausal women. Other health benefits and risks of supplementation at doses considered, including an elevation in urinary tract stone formation, appear to be modest and approximately balanced.

Female stone disease: the changing trend.

This paper has attempted to assess the changes noted in the trends in the incidence and biochemical pattern of female urolithiasis patients during the period 1971-2008. A prospective descriptive clinical study was done on 8,590 stone patients belonging to both sexes treated at the urinary stone clinic. The incidence of stone disease among the two sexes was plotted. The various metabolic parameters including 24-h urine volume, urine calcium, phosphorus, uric acid, oxalate, magnesium, creatinine and citrate, serum creatinine, calcium, phosphorus, uric acid and magnesium and calculated parameter calcium:magnesium ratio were studied. The possible causes for the change in incidence of stone disease in the female sex were elucidated. Of the patients studied, 12.7% (1,091) were females. There was a definite increase in the incidence of female urolithiasis over the past 37 years (P < 0.001). There were significant variations in urine biochemical parameters. There was a definite increase in the excretion of urinary calcium over the years (P < 0.001). The excretion rate of oxalate in urine of females also increased steadily over the years (P < 0.001). The magnesium in urine of females reduced over the years (P < 0.001). Urinary citric acid has however shown an increase over the years (P < 0.001). Urinary excretion of phosphorus (P < 0.001) and urinary uric acid (P < 0.001) showed a decreasing trend. There was a considerable increase in the percentage of females with high calcium:magnesium ratio over the years (P < 0.001). There was a definite decrease in female patients with hypercalcemia over the years. Serum phosphorus and magnesium also increased significantly with the passage of time. Serum uric acid did not vary significantly through the years. The decrease in the excretion rate of magnesium which is inhibitory to stone genesis, together with the increased excretion of calcium and oxalate may have contributed to the increasing incidence of stone disease in females. This might be due to changes in living standards and dietary habits.

Melamine-contaminated milk products induced urinary tract calculi in children.

BACKGROUND: Melamine is an industrial chemical used primarily as plastics stabilizer and fire retardant. On September 11, 2008, melamine-contaminated milk products were reported to be responsible for urinary tract calculi in infants and children in China. This study aimed to investigate the prevalence, lesions, risk factors, clinical features, and management of children fed with the melamine-contaminated milk products. METHODS: A total of 15 577 infants and children fed with the milk products were screened at our hospital. Ultrasonography was performed in all the infants and children. For those found with urinary tract calculion ultrasonography, urnalysis was done. Among them, 846 with detailed data screened from September 17 to 25 were enrolled for further analysis in this study. They were divided into calculus group (326 children) and non-calculus group (520 children) according to the results of ultrasonography. They included 429 boys and 417 girls, aged from 1 month to 5 years (median, 18 months). Their clinical and laboratory data, ultrasonograms, and treatment results were analyzed. RESULTS: Of the 15 577 children screened, 562 (3.61%) had urinary tract calculi. The rate was closely related to the melamine concentration in patients fed with formula. In 846 children with detailed data enrolled in this analysis, weight and head circumference Z scores in the calculus group were lower than those in the non-calculus group (P=0.048, P=0.046). Long duration of formula feeding, high melamine contained formula, and minimal water intake were the risk factors for calculi (P<0.05, respectively). Of 326 children with calculi, 281 had small calculiless than 0.5 cm in diameter, 227 had multiple calculi, and 34 had urinary tract distention. Moreover, diffuse renal lesions, renal failure and ascites were noted in 4, 3 and 2 patients, respectively. After 1-month treatment with sodium bicarbonate and Chinese traditional medicine, calculi disappeared in 49 of 54 outpatients. In 41 inpatients, 5 had calculi removed operatively and 36 had calculi minimized. CONCLUSIONS: Melamine-contaminated milk products induced urinary tract calculi, which have a good response to conservative therapy. Long-term follow-up of infants and children fed with melamine-contaminated milk products is required, and food safety should be supervised increasingly for the health of children.

Metabolic assessment in patients with urinary lithiasis.

INTRODUCTION: Metabolic investigation in patients with urinary lithiasis is very important for preventing recurrence of disease. The objective of this work was to diagnose and to determine the prevalence of metabolic disorders, to assess the quality of the water consumed and volume of diuresis as potential risk factors for this pathology. PATIENTS AND METHODS: We studied 182 patients older than 12 years. We included patients with history and/or imaging tests confirming at least 2 stones, with creatinine clearance > or = 60 mL/min and negative urine culture. The protocol consisted in the collection of 2, 24-hour urine samples, for dosing Ca, P, uric acid, Na, K, Mg, Ox and Ci, glycemia and serum levels of Ca, P, Uric acid, Na, K, Cl, Mg, U and Cr, urinary pH and urinary acidification test. RESULTS: 158 patients fulfilled the inclusion criteria. Among these, 151 (95.5%) presented metabolic changes, with 94 (62.2%) presenting isolated metabolic change and 57 (37.8%) had mixed changes. The main disorders detected were hypercalciuria (74%), hypocitraturia (37.3%), hyperoxaluria (24.1%), hypomagnesuria (21%), hyperuricosuria (20.2%), primary hyperparathyroidism (1.8%), secondary hyperparathyroidism (0.6%) and renal tubular acidosis (0.6). CONCLUSION: Metabolic change was diagnosed in 95.5% of patients. These results warrant the metabolic study and follow-up in patients with recurrent lithiasis in order to decrease the recurrence rate through specific treatments, modification in alimentary and behavioral habits.

Metabolic assessment in patients with urinary lithiasis

INTRODUCTION: Metabolic investigation in patients with urinary lithiasis is very important for preventing recurrence of disease. The objective of this work was to diagnose and to determine the prevalence of metabolic disorders, to assess the quality of the water consumed and volume of diuresis as potential risk factors for this pathology. PATIENTS AND METHODS: We studied 182 patients older than 12 years. We included patients with history and/or imaging tests confirming at least 2 stones, with creatinine clearance > 60 mL/min and negative urine culture. The protocol consisted in the collection of 2, 24-hour urine samples, for dosing Ca, P, uric acid, Na, K, Mg, Ox and Ci, glycemia and serum levels of Ca, P, Uric acid, Na, K, Cl, Mg, U and Cr, urinary pH and urinary acidification test. RESULTS: 158 patients fulfilled the inclusion criteria. Among these, 151 (95.5 percent) presented metabolic changes, with 94 (62.2 percent) presenting isolated metabolic change and 57 (37.8 percent) had mixed changes. The main disorders detected were hypercalciuria (74 percent), hypocitraturia (37.3 percent), hyperoxaluria (24.1 percent), hypomagnesuria (21 percent), hyperuricosuria (20.2 percent), primary hyperparathyroidism (1.8 percent) secondary hyperparathyroidism (0.6 percent) and renal tubular acidosis (0.6). CONCLUSION: Metabolic change was diagnosed in 95.5 percent of patients. These results warrant the metabolic study and follow-up in patients with recurrent lithiasis in order to decrease the recurrence rate through specific treatments, modification in alimentary and behavioral habits.

The effect of fruits and vegetables on urinary stone risk factors.

BACKGROUND: The overall effect of fruit and vegetable intake on urinary stone risk profile is not yet known. METHODS: We studied the effect of a two-week period of fruit and vegetable elimination on urinary stone risk profile in 12 normal adults, and of supplementing the diet with a fair quantity of low-oxalate fruits and vegetables in 26 idiopathic calcium stone formers characterized by hypocitraturia and a very low fruit and vegetable intake in their usual diet. RESULTS: In the normal subjects, the elimination of fruits and vegetables from the diet decreased the urinary excretion of potassium (-62%), magnesium (-26%), citrate (-44%) and oxalate (-31%), and increased that of calcium (+49%) and ammonium (+12%) (P < 0.05 for all). The relative saturation for calcium oxalate and calcium phosphate increased from 6.33 to 8.24 (P = 0.028), and from 0.68 to 1.58 (P = 0.050), respectively. In the hypocitraturic stone formers, the introduction of these foods in the diet increased urinary volume (+64%), pH (from 5.84 to 6.19), excretion of potassium (+68%), magnesium (+23%), and citrate (+68%), while it decreased the excretion of ammonium (-18%) (P < 0.05 for all). The relative saturation for calcium oxalate and uric acid fell from 10.17 to 4.96 (P < 0.001), and from 2.78 to 1.12 (P = 0.003), respectively. CONCLUSION: The total elimination of fruits and vegetables in normal subjects brings about adverse changes in the urinary stone risk profile that are only partially counterbalanced by a reduction in oxalate. In contrast, the addition of these foods to the diet of hypocitraturic stone formers not used to eating them not only significantly increases citrate excretion without affecting oxalate excretion, but also decreases calcium oxalate and uric acid relative saturation.

Renal response to lithogenic and anti-lithogenic supplement challenges in a stone-free population group.

OBJECTIVE: In South Africa, urolithiasis is extremely rare in the black population, but is common in the white population. The objective of this study was to investigate the individual effects of 5 different dietary and supplemental challenges (high dietary calcium, calcium supplement, vitamin B6 supplement, L-glutamine supplement, and L-cysteine supplement) on the urinary risk factors for calcium oxalate urolithiasis in subjects from both race groups. DESIGN: Complete Latin Square design. SETTING: University research laboratory. SUBJECTS: Subjects were recruited from the student cohort of the University of Cape Town (10 male subjects from each race group). Selection criteria were no history of renal or metabolic diseases, and no chronic or acute medication. Subjects served as their own controls. INTERVENTION: After 7 days on a self-selected standardized diet, a 24-hour baseline urine sample was collected. A second 24-hour urine sample was collected after 5 days on the prescribed dietary or supplemental challenge. These were analyzed for biochemical and physicochemical risk factors. Additionally, 24-hour dietary recall questionnaires were recorded at baseline and after the 5-day test period, and were analyzed using a food analysis program. Statistical analysis of variance was performed on all of the data. MAIN OUTCOME MEASURES: Urine composition, relative supersaturation of urinary salts, calcium oxalate metastable limit, and Tiselius risk index. RESULTS: None of the protocols altered any of the urinary biochemical or physicochemical risk factors in black subjects. In white subjects, the calcium diet significantly increased urinary potassium (P =.0001) and decreased the relative supersaturation of brushite (P =.035); the calcium supplement significantly decreased the Tiselius risk index (P =.014); vitamin B6 supplement significantly decreased urinary calcium (P =.016), urinary phosphate (P =.027), and the relative supersaturation of brushite (P =.004); L-glutamine supplement significantly decreased relative supersaturation of calcium oxalate (P =.01); L-cystine supplement significantly decreased urinary calcium (P =.031) and the Tiselius risk index (P =.013). CONCLUSIONS: Because none of the challenges had an effect on the urinary risk factors in black subjects, it is speculated that a renal or gastrointestinal homeostatic adjustment occurs in this group, thereby keeping urinary concentration of substances in balance.

Idiopathic calcium oxalate urolithiasis: risk factors and conservative treatment.

Idiopathic calcium oxalate urolithiasis is a frequent and recurrent multifactorial disease. This review focuses on urinary and dietary risk factors for this disease and conservative strategies for rectifying them. Dietary oxalate and calcium and their respective urinary excretions have been extensively investigated during the last 10 years. Urinary oxalate has emerged as the most important determinant of calcium oxalate crystallization while the role of urinary calcium has shifted to bone balance and osteoporosis. Dietary calcium restriction increases urinary oxalate and contributes to a negative bone balance. It has therefore been abandoned as a means to reduce the risk of calcium oxalate kidney stone formation. Calcium oxalate kidney stone patients are advised to increase their fluid intake to achieve a urine volume of 2 l or more; the recommended calcium intake is 800-1200 mg/day; high oxalate foods should be restricted; daily protein intake should be between 0.8 and 1 g/kg body weight/day; essential fats should be included; vegetable and fruit (except oxalate-rich vegetables) intake should be increased. The use of calcium supplements has potential benefits but needs to be examined further.

[Urinary lithiasis of medical origin]. / Les lithiases urinaires d'origine médicamenteuse.

Analysis of 22,510 urinary calculi between January 1991 to July 2000 performed by infrared spectroscopy allows for separation of drug-induced urolithiasis into two categories: first, the drugs physically embedded in the stone (n = 238; 1.0 per cent), notably indinavir monohydrate (n = 126; 52.9 per cent), followed by triamterene (n = 43; 18.1 per cent), sulphonamides (n = 29; 12.2 per cent) and amorphous silica (n = 24; 10.1 per cent); second, the category of metabolic nephrolithiasis induced by drugs (n = 140; 0.6 per cent), involving mainly calcium and vitamin D supplementation (n = 56; 40.0 per cent) and carbonic anhydrase inhibitors (n = 33; 23.6 per cent). Composition of the stone depended not only on the inducer drug but also on the metabolic state of the patient. Today, drug-induced stones comprise about 1.6 per cent of all calculi in France. Physical analysis and therapeutic history recall of such patients are the keys to diagnosis. Medical care is based on drug avoidance or dose adjustment with increased diuresis and, if necessary, change in urinary pH.

Urinary calculi: bacteriological and chemical association.

We investigated the bacteriology of urinary calculi in relation to urinary tract infection, stone formation, chemical composition and antibiotic sensitivity. Fifty-two patients (37 males, 15 females) with urolithiasis were studied. Urine, serum and urinary calculi specimens were taken and serum biochemical tests to detect uric acid, calcium and phosphorus were performed. Urine analysis and culture were also performed. Of the 52 patients, 19 (37%) had associated urinary tract infection, with Escherichia coli and Proteus mirabilis being the most common causative microorganisms. The bacterial isolates from urine and those from calculi differed in their susceptibility to antimicrobial agents. We conclude that in over 50% of patients with urolithiasis, urine culture can detect the infecting organisms associated with stone formation and the organisms within urinary calculi.

Epidemiology of canine calcium oxalate uroliths. Identifying risk factors.

Calcium oxalate uroliths are most commonly encountered in Miniature Schnauzers, Lhaso Apsos, Yorkshire Terriers, Bichons Frises, Shih Tzus, and Miniature Poodles. They are more common in males than females, and more common in older than young dogs. Dogs that form abnormal nephrocalcin are also predisposed to calcium oxalate uroliths. Dietary risk factors for calcium oxalate uroliths include excessive calcium supplementation or excessive calcium restriction, excessive oxalic acid, high protein, high sodium, restricted phosphorus, restricted potassium, and restricted moisture (dry formulations). Dogs with hyperadrenocorticism or hypercalcemia are predisposed to calcium oxalate urolith formation.

[Drug-induced urinary calculi in 1999]. / Les lithiases urinaires médicamenteuses en 1999.

Drug-induced urolithiasis are observed in 1.6% of the urinary calculi in France. Drugs crystals are identified in two thirds of these stones. Other drugs are responsible for stones which have an apparent metabolic origin (one third of the cases). Stone analysis using physical methods such as infrared spectroscopy is needed to unambiguously identify stones containing drugs. The inquiry is an important step to identify lithogenetic drugs which do not crystallize in the stones. The main substances which were identified in stones over the past decade were indinavir monohydrate (31.4%), triamterene (11.1%), sulphonamides (10.5%) and amorphous silica (4.5%). The main drugs involved in the nucleation and growth of metabolic stones were calcium and vitamin D supplementation (15%) and long-term treatment with carbonic anhydrase inhibitors (8%). Stone prevention is based on drug withdrawal or change in dosage with additional measures including an increase of diuresis and, if necessary, changes in the urine pH.

Trial of calcium to prevent preeclampsia.

BACKGROUND: Previous trials have suggested that calcium supplementation during pregnancy may reduce the risk of preeclampsia. However, differences in study design and a low dietary calcium intake in the populations studied limit acceptance of the data. METHODS: We randomly assigned 4589 healthy nulliparous women who were 13 to 21 weeks pregnant to receive daily treatment with either 2 g of elemental calcium or placebo for the remainder of their pregnancies. Surveillance for preeclampsia was conducted by personnel unaware of treatment-group assignments, using standardized measurements of blood pressure and urinary protein excretion at uniformly scheduled prenatal visits, protocols for monitoring these measurements during the hospitalization for delivery, and reviews of medical records of unscheduled outpatient visits and all hospitalizations. RESULTS: Calcium supplementation did not significantly reduce the incidence or severity of preeclampsia or delay its onset. Preeclampsia occurred in 158 of the 2295 women in the calcium group (6.9 percent) and 168 of the 2294 women in the placebo group (7.3 percent) (relative risk, 0.94; 95 percent confidence interval, 0.76 to 1.16). There were no significant differences between the two groups in the prevalence of pregnancy-associated hypertension without preeclampsia (15.3 percent vs. 17.3 percent) or of all hypertensive disorders (22.2 percent vs. 24.6 percent). The mean systolic and diastolic blood pressures during pregnancy were similar in both groups. Calcium did not reduce the numbers of preterm deliveries, small-for-gestational-age births, or fetal and neonatal deaths; nor did it increase urolithiasis during pregnancy. CONCLUSIONS: Calcium supplementation during pregnancy did not prevent preeclampsia, pregnancy-associated hypertension, or adverse perinatal outcomes in healthy nulliparous women.

[The usefulness of dual-energy radiographic densitometry (DO) in establishing the composition of calculi]. / Utilidad de la densitometría radiográfica de energía dual (DO) en el establecimiento de la composición litiásica.

Dual-energy radiographic bone densitometry is utilized to determine the bone mineral content in patients with osteoporosis. The present in vitro experimental study investigated the usefulness of densitometry in determining stone composition and in evaluating the mineral and non mineral phases of the calculus. For the study we analyzed 114 calculi of 6 different chemical composition (calcium oxalate monohydrate, calcium oxalate dihydrate, magnesium ammonium phosphate, phosphate carbonate, uric acid and phosphate oxalate). The phosphate carbonate calculi had the highest mineral density, whereas the uric acid calculi had the lowest and contained more water. Although densitometry appears to be of little value in determining stone composition, it provides information on the mineral and non mineral phases of the calculus.