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PubMed2004

Nephrolithiasis and pregnancy.

PURPOSE OF REVIEW: Urolithiasis during pregnancy is not common, however, it is a difficult condition to both diagnose and treat. There are many safety concerns that must be considered for both the mother and fetus. In this review we detail the different options available to the urologist and we highlight a treatment algorithm that we use when faced with a pregnant patient suspect of having a urinary calculus. RECENT FINDINGS: Changes in ultrasound, limited intravenous urograms and magnetic resonance imaging have improved our ability to diagnose urolithiasis in pregnancy. Additionally ureteroscopy has emerged not only as a diagnostic tool but also as a modality for definitive treatment that can safely be used during the intrapartum period. SUMMARY: When diagnosing urolithiasis in the gravid patient, the first line study should be ultrasound, using change in resistive index and transvaginal ultrasound. If these are not diagnostic, then a limited intravenous urograms should be performed. Once a diagnosis has been established, initial treatment should be conservative since 70-80% of patients will pass their stones. When intervention is necessary, the placements of an internal stent or percutaneous nephrostomy tube or ureteroscopy with definitive stone treatment are all reasonable options.

Female↗
PubMed2003

Changes in urine volume accomplished by physicians treating nephrolithiasis.

PURPOSE: We quantified the changes in urine volume and sodium accomplished in various practice settings and the consequent effects on calcium oxalate supersaturation. MATERIALS AND METHODS: We determined comprehensive urine stone risk factors in 2,877 patients treated in 14 practices, including a university referral center and private sector practices. Changes in urine volume and stone risk factors were measured. RESULTS: In a wide range of practice settings the volume increase was about 0.3 l. daily. Urine sodium excretion increased with volume for unexplained reasons, as did urine calcium excretion. As expected, thiazide lowered calcium excretion but the effect progressively decreased as urine volume increased. Therefore, urine calcium and calcium oxalate supersaturation changes were the result of opposing forces. The net effect was a decrease partly offset by sodium and calcium excretion increases. CONCLUSIONS: Urine volume increments are modest in practice and they are modestly offset by increases in urine sodium due to increased sodium intake. Clinicians should strive for higher volume increases than are currently achieved and be vigilant concerning what seems to be a strong tendency toward a higher sodium intake with more fluids.

Benzothiadiazines↗
PubMed2004

Outcome of metabolic evaluation and medical treatment for calcium nephrolithiasis in a private urological practice.

PURPOSE: We determine if medications that have been proven effective for kidney stone prevention in prospective controlled trials can reduce kidney stone recurrence in a private practice of urology better than life-style advice, including hydration. MATERIALS AND METHODS: Between July 1, 1995 and December 31, 1996, 203 patients with stones received care from 1 private practice. Physicians chose to evaluate these patients metabolically based on clinical judgement. Thiazide, potassium citrate and allopurinol are recognized in this study as active treatments, and drug treatment intervals were calculated. Relapse and recurrent stones were counted as those stones manifesting after the initial index event. A stone was called a relapse stone if its date was included in the active treatment interval. RESULTS: The association between use of active therapy and ordering of metabolic evaluation was highly significant. Using survival tables, we separately considered all patients and only those who had formed more than 1 stone. For both populations active treatment reduced stone recurrence significantly more than diet advice and hydration. CONCLUSIONS: Medications validated in trials and guided by metabolic evaluation lower stone recurrence when used in a private practice setting as they do in trials.

Calcium↗
PubMed2004

Metabolic risk factors and the impact of medical therapy on the management of nephrolithiasis in obese patients.

PURPOSE: Previous studies have demonstrated that obesity can increase the risk of stone formation as well as recurrence rates of stone disease. Yet appropriate medical management can significantly decrease the risk of recurrent stone disease. Therefore, we analyzed our obese patient population, assessing the risk factors for stone formation and the impact of selective medical therapy on recurrent stone formation. MATERIALS AND METHODS: A retrospective chart review was performed to identify obese patients with stone disease from our Stone Center. Metabolic risk factors for stones were identified as well as patient response to medical therapy. A similar analysis was performed on a group of age and sex matched nonobese stone formers. RESULTS: Of 1,021 patients 140 (14%) were identified as obese (body mass index greater than 30). Of these patients complete metabolic evaluations were available in 83 with an average followup of 2.3 years. The most common presenting metabolic abnormalities among these obese patients included gouty diathesis (54%), hypocitraturia (54%) and hyperuricosuria (43%), which presented at levels that were significantly higher than those of the nonobese stone formers (p <0.05). Stone analysis was available in 32 obese patients with 63% having uric acid calculi. After initiating treatment with selective medical therapy obese and nonobese patients demonstrated normalization of metabolic abnormalities, resulting in an average decrease in new stone formation from 1.75 to 0.15 new stones formed per patient per year in both groups. CONCLUSIONS: Obesity, as a result of dietary indiscretion, probable purine gluttony and possible type II diabetes, appears to have a significant role in recurrent stone formation. Appropriate metabolic evaluation, institution of medical therapy and dietary recommendations to decrease animal protein intake can significantly improve the risk of recurrent stone formation in these often difficult to treat patients.

Adolescent↗
PubMed2005

Preventive effects of green tea on renal stone formation and the role of oxidative stress in nephrolithiasis.

PURPOSE: Urinary stones are similar to arteriosclerosis in epidemiology, mechanism, calcification composition and age at frequent occurrence. The calcification that occurs in arteriosclerosis is inhibited by antioxidants. Green tea leaves contain approximately 13% catechins, which have been shown to have antioxidant effects. We investigated the inhibitory, antioxidative effects of green tea on calcium urinary stone formation. MATERIALS AND METHODS: A total of 120 Wistar rats were divided into 4 groups, namely group 1-control rats receiving saline, group 2-stone group rats administered ethylene glycol (EG) and vitamin D3, group 3-drink group rats administered EG, vitamin D3 and green tea given as drinking water, and group 4-powder group rats administered EG, vitamin D3 and 2.5% powdered green tea leaves mixed in a powder diet. Pooled 24-hour urine samples and blood samples were collected and the 2 kidneys were excised 7, 14 and 21 days after administration, respectively. One kidney was used for immunohistological examination of osteopontin, superoxide dismutase (SOD), p65, p53 and bcl-2 expression, in situ hybridization of osteopontin and detection of apoptosis, while the other was used for quantitative analysis of SOD activity. RESULTS: Green tea treatment decreased urinary oxalate excretion and calcium oxalate deposit formation. Green tea treatment increased SOD activity compared with the stone group. The degree of apoptosis in the stone group was significantly increased compared with the drink and powder groups. CONCLUSIONS: The inhibitory effect of green tea on calcium oxalate urolithiasis is most likely due to antioxidative effects.

Animals↗
PubMed2004

Cost-effectiveness of medical management strategies for nephrolithiasis.

PURPOSE: We evaluated the cost-effectiveness and stone recurrence rates of common management strategies in stone formers. MATERIALS AND METHODS: A decision tree model was created to compare the costs of 6 medical treatment strategies, namely dietary measures alone (conservative), empiric drug treatment (empiric), or directed drug therapy based on simple or comprehensive metabolic evaluation. The model assumed cost accrual for evaluation, medications, emergency treatment and surgery for stone recurrence. We determined recurrence rates, medical evaluation sensitivity and the risk reduction of medical treatments from the literature and the costs of surgery, emergency room and medical evaluation at our county hospital. Drug costs were obtained from 2 national pharmacy chains. RESULTS: In first time stone formers conservative treatment was the least costly strategy and it yielded a stone formation rate of 0.07 stones per patient yearly. In recurrent stone formers conservative treatment was less costly than drug treatments but it was associated with a higher stone recurrence rate (0.3 stones per patient yearly). The remaining drug treatments were more costly than conservative treatment ($885 to 1,187 vs $258 yearly) but they further decreased recurrence rates by 60% to 86%. Modified simple medical evaluation and management (SMEM), that is drug treatment in all patients after simple evaluation) was slightly more costly than empiric treatment and minimally more effective. Comprehensive evaluation and treatment offered no advantage in cost or efficacy over empiric treatment or modified SMEM. CONCLUSIONS: In first time stone formers conservative therapy is cost-effective and efficacious. In recurrent stone formers conservative therapy is unsatisfactory despite low cost because of a high recurrence rate. Modified SMEM and empiric therapy yield the same cost and efficacy as treatments that follow comprehensive evaluation. However, modified SMEM may be advantageous because it offers useful additional medical information.

Cost-Benefit Analysis↗
PubMed1990

Hyperoxaluria or hypercalciuria in nephrolithiasis: the importance of renal tubular functions.

The role of the kidney in states of hyperoxaluria and hypercalciuria was investigated in seven patients with hyperoxaluria after jejunoileal bypass (JIB) and six patients with idiopathic hypercalciuria (IHC). Eight apparently healthy persons formed a control group. Besides hyperoxaluria, the patients with JIB displayed an elevated plasma concentration of oxalate and the oxalate clearance was increased and higher than creatinine clearance, indicating a net tubular secretion of oxalate. The JIB patients had lower 24-h urinary excretions of calcium, phosphate, magnesium and citrate and higher serum parathyroid hormone (PTH) than controls, indicating increased secretion of PTH to compensate for calcium malabsorption. IHC patients exhibited increased fasting urinary calcium even though their serum values were similar to those in the controls. These results indicate a reduced tubular calcium reabsorption, which was most pronounced in patients with highest PTH values. We conclude that hyperoxaluria in JIB patients is associated both with intestinal hyperabsorption and with enhanced tubular secretion of oxalate, and that in some patients with IHC hypercalciuria is due to reduced tubular reabsorption of calcium.

Adult↗
PubMed1993

Nephrolithiasis in Iranian sheep.

Out of 500 Iranian sheep examined, six revealed the presence of lithiasis in their kidneys. Nephroliths in three animals were composed of ammonium magnesium phosphates and in the others of calcium carbonates and calcium phosphates. Interestingly sodium and ammonium urate crystals were present in the kidneys of three animals.

Abattoirs↗
PubMed1979

Nephrolithiasis.

Explore the source record for details and available documents.

Calcium↗
PubMed2006

Reduced renal function and benefits of treatment in cystinuria vs other forms of nephrolithiasis.

UNLABELLED: A significant study from the USA compares cystine stone formers and routine stone formers; the former group had a higher requirement for therapeutic procedures, but this was less if they took chelating agents, although remaining higher than in the latter group. Other interesting findings are also presented. OBJECTIVE: First, to compare two types of stone formers (SF), those with cystinuria and those without, for effects of treatments for stones, as cystinuria leads to recurrent stones that are difficult to fragment with shock-wave lithotripsy, and there is disagreement about the efficacy of current treatments. Second, to compare these two groups with respect to blood pressure (BP) and renal function, as cystine stones may be associated with more morbidity than are routine stones. PATIENTS AND METHODS: Fifty-two cystinuric patients (cystine SF) entering our programme since 1970 were compared with 3215 SF without cystinuria (routine SF), of whom 114 had a single functioning kidney (routine SF + nephrectomy). All patients had three 24-h urine and blood samples taken to determine the risk of stones before their first clinic visit; these studies were repeated after therapy was initiated, and at regular intervals to monitor therapy. Cystine was measured in the urine samples of the cystine SF. All stone-related procedures were recorded, and BP measured at clinic visits. Creatinine clearances (CCr) were calculated from each set of serum and urine values. Cystine supersaturation (SS) was directly measured in 16 urine samples collected before treatment and 13 afterward. RESULTS: Patients were treated with increased fluid intake, potassium alkali and chelating agents such as alpha-mercapto-propionyl-glycine, as needed. The mean (sd) CCr, corrected for age and gender, was significantly lower at entry in cystine SF than in routine SF, at 91 (6) vs 160 (1) L/day, respectively (P < 0.001), and remained so at the last CCr. Neither systolic nor diastolic BP, similarly corrected, differed between the groups, but cystine SF had significantly more procedures, corrected for time at risk, before treatment than did routine SF, at 4.0 (0.4) vs 1.86 (0.06), respectively (P < 0.001); time-adjusted procedures decreased significantly in both groups during treatment, but remained higher in cystine SF, at 0.88 (0.14) vs 0.23 (0.02), respectively, (P < 0.001). Urine volume and pH were significantly higher in cystine SF than in routine SF, both before and during treatment. Cystine SS decreased during treatment, consistent with the increase in urine volume and decline in procedure rates during treatment. CONCLUSION: Cystine SF have significantly higher procedure rates than routine SF, but procedure rates decline during therapy, although they remain higher than in routine SF. The lower CCr in cystinurics suggests that treatment to prevent stone recurrence and the need for procedures is particularly important, and emphasizes the need for a close follow-up. Use of cystine SS measurements may allow closer monitoring of the effect of treatment on the risk of stone recurrence.

Adult↗
PubMed2005

Crystal-associated nephropathy in patients with brushite nephrolithiasis.

BACKGROUND: We have biopsied the renal cortex and papillae of patients who form brushite renal stones asking if this unusual stone type is associated with specific tissue changes. We contrasted these with biopsies of 15 calcium oxalate stone formers, three stone formers with intestinal bypass, and four normal subjects. METHODS: We studied all ten brushite stone formers treated with percutaneous nephrolithotomy (PNL) during the past 3 years using digital video imaging of renal papillae, and obtained cortical and papillary biopsies. Biopsies were analyzed by light and electron microscopy, microinfrared spectroscopy, and electron diffraction. RESULTS: Apatite crystals plugged scattered terminal collecting ducts whose cells were injured or dead, and surrounding interstitium inflamed and fibrotic. White papillary deposits of interstitial apatite particles, so called Randall's plaque, were also present. Glomerular changes and cortical tubular atrophy and interstitial fibrosis were moderate to severe. CONCLUSION: Brushite stone formers combine the interstitial plaque of calcium oxalate stone formers with the collecting duct apatite plugs found in stone formers with intestinal bypass. Collecting duct injury and interstitial fibrosis are severe. Prominent cortical fibrosis, tubule atrophy, and glomerular pathology seem secondary to the collecting duct plugging. We believe crystallization obstructs and destroys terminal collecting duct segments thereby damaging nephrons, perhaps via intranephronal obstruction, and producing a hitherto unrecognized renal disease.

Adolescent↗