Can a relationship reflect the risk of calcium oxalate urolithiasis?

Different mathematical expressions have been proposed in the literature with the aim to reflect the risk of calcium oxalate urolithiasis. Such expressions, as well as a number of new relationships proposed by us, have been evaluated in 76 patients and 34 normal subjects. Stone-formers were divided into two groups: patients with normal calcium and oxalate excretion and patients with hypercalciuria and/or hyperoxaluria. The results obtained were comparatively evaluated. Several formulae gave some acceptable results, but none of them were excellent. This can be explained by the fact that these discrimination indexes more or less reflect supersaturation and/or inhibition deficit, but none of them reflect promoting factors such as heterogeneous nucleation and/or aggregation capacity.

Irritability and dysuria in infants with idiopathic hypercalciuria

Idiopathic hypercalciuria (IH) is being diagnosed with increasing frequency in the pediatric population and occurs in approximately 2.9-6.2% of normal children. The majority of children with IH are asymptomatic; however, the most common clinical presentation is that of isolated hematuria (gross or microscopic). The prevalence, presentation and clinical course of IH is less well established in infants. We have recently seen two young infants with IH who had dysuria on presentation. Their hypercalciuria was difficult to manage and required frequent manipulations of drug therapy and diet restrictions. These cases emphasize the importance of evaluating infants with dysuria and irritability for IH, even in the absence of hematuria. Further studies are needed to establish the prevalence and classical presentation of IH in this population, and to determine the necessary duration of therapy.

Medical dissolution of feline struvite urocystoliths

The efficacy of a diet designed to facilitate dissolution of feline magnesium ammonium phosphate (struvite) uroliths was evaluated in 30 cases of urolithiasis, sterile struvite uroliths dissolved in a mean of 36 days after initiation of dietary treatment. In 5 cases of urolithiasis, struvite urocystoliths associated with urease-negative bacterial urinary tract infection dissolved in a mean of 23 days after initiation of dietary and antimicrobial treatment. In 3 cases of urolithiasis, struvite urocystoliths associated with urease-positive staphylococcal urinary tract infection dissolved in a mean of 79 days after initiation of dietary and antimicrobial treatment. Dissolution of uroliths in cats fed the treatment diet was associated with concomitant remission of dysuria, hematuria, and pyuria, and reduction in urine pH and struvite crystalluria. In one case, a urocystolith composed of 100% ammonium urate, and in another case, a urolith composed of 60% calcium phosphate, 20% calcium oxalate, and 20% magnesium ammonium phosphate did not dissolve.

[Urinary calculus protective side effects of anti-rheumatic therapy]

In a retrospective study two patient groups suffering from recurrent calcium oxalate lithiasis are compared before and after antirheumatic therapy using Diclofenac-Natrium alone or in combination with xanthine oxidase inhibitors and/or hydrochlorothiazides. The examination of concentration and excretion of lithogenic important parameters show a partly significant reduction of the concentration mean values of calcium, oxalic acid and uric acid. The influence of non-steroidal antiphlogistics (NSAP) on calculus recurrence rate in calcium oxalate lithiasis is recognized.

Biochemical mechanisms and effects of Mimosa pudica (Linn) on experimental urolithiasis in rats

Urolithiasis, following implantation of Zn discs in urinary bladder (foreign body insertion technique), was examined in albino rats of either sex. Marked variation was observed between sex, regarding the formation of bladder stones. Ethylene glycol (1%) mixed in drinking water for 4 weeks, was unable to augment Zn disc-induced stone deposition. Chemical nature of stones was identified as of magnesium ammonium phosphate type. Neither urinary pH nor infection in the urinary bladder/tract affected chemical nature and quantity of stone formed. There was no significant influence of electrolytes or metabolic products on the uroliths. No correlation could be drawn between the quality and quantity of uroliths formed and the urinary electrolytes concentration. M. Pudica was not effective in either preventing stone deposition or dissolving preformed stones.

Determination of urinary oxalate by high-performance liquid chromatography monitoring with an ultraviolet detector

High-performance liquid chromatography (HPLC) monitoring with an ultraviolet detector was carried out to measure urinary oxalate levels in urolithiasis. Interfering substances in urine were removed by anion exchange prior to chromatography. This procedure was found excellent with respect to sensitivity, reproducibility, and analytical recovery. The findings were in agreement with colorimetric date. The mean oxalate level in 24-hour urine was 30.5 +/- 15.1 mg in patients with a single episode and 36.3 +/- 9.8 mg in recurrent stone formers. The latter values was significantly higher than the normal control level (27.4 +/- 3.8 mg).

A simple technique for studying struvite crystal growth in vitro

Struvite urolithiasis forms as a consequence of a urinary tract infection by urease-producing species of bacteria such as Proteus mirabilis. Ammonia, produced by the enzymatic hydrolysis of urea, elevates urine pH causing a supersaturation and precipitation of Mg++ as struvite (NH4MgPO4). Calcium often precipitates as well, forming the mineral carbonate-apatite (Ca10(PO4)6CO3). We have developed a procedure based on direct observation by light microscopy whereby struvite crystal growth can be quickly monitored in response to chemical changes in urine. As struvite crystals assume a characteristic shape or crystal habit based on their growth rate, the effect of urine chemistry and the action of various crystallization or urease inhibitors on struvite formation can be quickly shown. In addition preliminary effects of alkaline pH, or the presence of toxic compounds on bacteria can also be shown through their loss of motility.

Hydration feature of urinary compounds. Evidence for molecular abnormality in calcium oxalate urolithiasis

Proton-relaxation-time measurements were performed on lyophilized urine samples collected from 11 recurrent calcium oxalate stone-formers, 9 uric acid stone-formers, 9 patients with various urological disorders, and 20 normal individuals. The T1 and T2 relaxation times were determined using a Bruker PC Multispec at 20 MHz at 37 degrees C for measurements of lyophilized sample and thereafter during gradual controlled rehydration. The prolongation of the relaxation times as a function of rehydration was found to differ significantly (P less than 0.005) between, on the one hand, the calcium oxalate stone-formers and, on the other hand the normal, uric-acid stone-formers, and patients with other urological disorders. Water compartmentalization was then calculated according to the fast proton diffusion model. At most of the experimental points during rehydration process, significantly (P less than 0.001) less water was bound to the compounds of urine from calcium oxalate stone-formers than that obtained from normal individuals. The variations in the bound hydration water may have been associated with possible changes in the structure or configuration of the compounds present in the urine of the different groups. The results reflect differences in the urinary content and/or properties of normal subjects and calcium oxalate stone-formers, and indicate that the mechanism of bound water relaxation is in some way specific to the pathophysiological state of urine.

Effects of different doses of alkaline citrate on urine composition and crystallization of calcium oxalate

Prophylactic treatment with alkaline citrate in patients with recurrent calcium oxalate (CaOx) stone disease results in reduced CaOx supersaturation and increased urinary citrate. The effects of a single evening dose were compared with those of two and three daily doses in six recurrent CaOx stone formers with hypercalciuria, hypocitraturia or raised calcium/citrate quotients. While on a standardized hospital diet the patients were given 7.5 g (28 mmol) of sodium potassium citrate (URALYT-U) in one, two, and three doses. Fractional urine collections during 24 hours were analyzed for pH, composition, and crystallization risk (CR). All dosage regimens had favourable effects on urinary calcium, citrate, calcium/citrate quotients, and CaOx-CR. The most sustained effect was recorded with three divided doses. Single evening doses resulted in the most pronounced effects between 22.00-06.00 h, thereby counteracting the increased risk of CaOx crystallization during that period. In terms of 24h urine composition the best effect was recorded with alkaline citrate administered three times daily, but because of the favourable response by a single evening dose between 22.00-06.00 h the assumption was made that this dosage regimen might be sufficient to reduce the risk of CaOx crystallization and stone formation. However, the validity of such an assumption can only be established by long-term clinical studies.

Glycose aminoglycane excretion and concentration in the urine of patients with frequently recurrent calcium-oxalate lithiasis prior to and following Diclofenac-Na therapy

Excretion and concentration of glycose aminoglycans were measured in 19 patients with frequent relapses of calcium-oxalate lithiasis, prior to and two weeks after onset of Diclofenac-Na therapy. In most patients, markedly enhanced glycose aminoglycan concentration and excretion could be demonstrated. Elevation of the high-molecular inhibitor potential in the urine results in reduced risk of calcium-oxalate lithogenesis, which may explain the therapeutic success of nonsteroidal anti-inflammatory drugs in the treatment of therapy resistant calcium-oxalate lithiasis.

Chemical measurement of calcium oxalate crystalluria: results in various causes of calcium urolithiasis

Calcium oxalate and calcium phosphate crystalluria have been measured chemically in 1,173 urine samples whose chemical compositions were also analysed. The importance of urinary oxalate as a determinant for calcium oxalate crystalluria was confirmed. Significant concentrations of calcium oxalate crystals may be present in urine even though the crystals are too small for detection by light microscopy or by many particle-counting methods. Calcium phosphate crystals in urine always contain a small proportion of calcium oxalate. Results in various clinical situations are reviewed.

Predictive value of some biochemical indices in stone formers

Search is under way to develop reliable tests for the prediction of stone risk. Several indices and ratios on the basis of urinary excretions have been suggested. In the present study the applicability of some risk indices and ratios in slum dwellers of Dharavi area of Bombay was examined. No significant difference was observed in IAP (ionic activity product) and CORI (calcium oxalate risk index) between stone formers (SF) and normal subjects (NS). We have suggested two more adjuncts, PIR (promoter/inhibitor ratio) and COQ (calcium oxalate quotient), and found them to be quite useful in the detection of risk. Pre-existence of risk factor(s) in the majority of the normal population suggests that triggering of stone formation should be a transient phenomenon in this population. No consistent pattern of relationship between various urinary parameters was observed.

On the relation between citrate and calcium in normal and stone-former subjects

The aim of this work is to evaluate citrate in a group of patients with calcium oxalate urolithiasis and in a control group for detecting possible differences between the two groups. The mean urinary concentration in the stone-formers was found significantly lower than in the controls. Particularly interesting was the correlation study between citrate and calcium. It was found that patients with hypocitraturia have hypercalciuria. Thus, it is particularly interesting to point out the importance of citrate in preventing the risk of lithiasis in the group of stone-formers studied by us.

The role of hyperoxaluria in the formation of calcium oxalate urinary calculi, and its association with other biochemical measurements

The part played by hyperoxaluria in the formation of calcium oxalate urinary calculi was studied in 153 patients who had each been diagnosed as having calcium oxalate urinary calculi on one or more occasions. Seventy-seven of the patients excreted normal amounts of calcium (less than 6.2 mmol/d), and 76 had hypercalciuria (excretion greater than or equal to 6.2 mmol/d); each group was divided into a further two groups depending on whether the oxalate concentration was above or below 0.16 mmol/l. Pure calcium oxalate stones were more common in patients whose calcium excretion was normal, and mixed calcium oxalate and phosphate stones were more common among hypercalciuric patients. Urinary concentrations/day of magnesium, citrate, and phosphorus were significantly lower in the two groups in which the oxalate concentrations were below 0.16 mmol/l than in a normal control group, and magnesium and phosphorus were significantly lower in the two groups in which oxalate concentrations were less than 0.16 mmol/l than in the two in which they were above that value. The concentration of citrate was also lower, but not significantly so. In addition, the pH of the urine in patients with mixed stones was significantly higher in all groups than when the stones were composed of pure calcium oxalate.

[The role of immunologic factors in the pathogenesis of urolithiasis]

The role of thrombin, fibrinogen, specific and unspecific immunological reactions in the pathogenesis of urolithiasis were evaluated. It was found in the urine of patients with urolithiasis and concomitant pyelonephritis that most bacteria, leucocytes and organic substances fixed on crystalloids contained on their surfaces immunoglobulins M, G and A. The mechanisms of the possible participation of immune reactions in the pathogenesis of urolithiasis are discussed.

How are urine composition and stone disease affected by therapeutic measures at an outpatient stone clinic?

Urine composition in terms of calcium oxalate (CaOx) supersaturation was studied in 802 patients with calcium stone disease before any intervention and during follow-up. Supersaturation was expressed as the AP(CaOx) index, a simplified estimate of the ion activity product of CaOx, and a similar index calculated for a 24-hour urine volume of 1.5 liters the AP(CaOx) index(s). The AP(CaOx) index was significantly reduced in men with and without medical treatment who remained stone-free during follow-up (p less than 0.001), but not in men who continued to form stones. For the AP(CaOx) index(s), a significant reduction was observed only in patients on medical treatment without new stone formation (p less than 0.01). In women, significantly lower AP(CaOx) index values were recorded in recurrent as well as non-recurrent stone formers on medical treatment, whereas in the group without medical treatment and without recurrences the difference did not reach a statistically significant level. This was similar to the effect on the AP(CaOx) index(s) in non-recurrent women with medical treatment. The small number of women with recurrences might have influenced the result. Significantly reduced levels of the AP(CaOx) index were recorded for patients given thiazide, thiazide + magnesium, magnesium, and alkaline citrate. The AP(CaOx) index(s) was reduced in patients given thiazide + magnesium, magnesium, and alkaline citrate. Comparison between the effects on urine composition and clinical response showed that the reduced CaOx supersaturation observed with thiazide, thiazide + magnesium, and alkaline citrate, corresponded to a low rate of stone formation during follow-up. The inefficiency of allopurinol and orthophosphate in affecting urine supersaturation was reflected in a higher recurrence rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Matrix crystals in cytologic urine specimens

Three cytologic urine specimens from separate patients seen over a period of 3 mo were prepared by the Papanicolaou method. They contained crystals (uric acid type in two and magnesium ammonium phosphate in one) that incorporated variable amounts of organic (mucoprotein) matrix; many appeared by light microscopy to be made exclusively of matrix. Scanning electron microscopy performed in one of the specimens containing uric acid crystals suggested that the matrix forms were in progressive stages of mineralization. These cases, plus a similar one reported recently by us, demonstrate that the detection by urine cytology of organic matrix incorporated in the structure of urinary crystals is not rare and that the Papanicolaou staining method facilitates such detection.

Relationship of plasma and urine composition to recurrence of calcium urinary stones in patients on drug therapy

Factors relating alterations in plasma and urine composition to recurrence of urinary stones during drug therapy were investigated by using a multiple regression analysis technique. These factors were influenced not only by the efficacy of the drugs but also by other factors (plasma or urinary constituents and overall health of the patients, etc.). In order to study the effect of drug therapy or other treatment on the alteration of plasma and urine constituents, multiple regression analysis is more appropriate than Student's paired t-test which has been used by some workers. These two analytical methods yield different results even if used on the same data.

Uric acid excretion in children with urolithiasis

Urinary uric acid excretion was assessed in 38 children to determine whether hyperuricuria was a risk factor in children with urolithiasis. Uric acid excretion (measured per deciliter glomerular filtration rate), and fractional excretion of uric acid were similar in 27 children with hypercalciuria and calcium oxalate urinary stones, in six children with idiopathic calcium oxalate urolithiasis, and in five with uric acid urolithiasis, of whom four were white boys and one was an Asian girl. One boy with a urate stone had cystinosis. Serum uric acid concentrations exceeded 6.0 mg/dl (360 mumol/L) in two children with hypercalciuria and in two patients with idiopathic calcium oxalate urolithiasis. None of the children with calcium urolithiasis had excessive urinary excretion of uric acid. In children with hypercalciuria, uric acid excretion did not change significantly when dietary sodium was increased from 1.0 to 5.0 gm/1.73 m2. We conclude that excessive urinary uric acid excretion is seldom an additional risk factor in children with calcium urolithiasis and that dietary sodium chloride does not have a strong influence on urinary excretion of uric acid in children with hypercalciuria.

Effect of captopril on urinary cystine excretion in homozygous cystinuria

We determined if captopril could reduce urinary cystine excretion in homozygous cystinuric patients. Seven patients were treated with 150 mg. captopril daily after determination of baseline 24-hour urine cystine excretion. All patients had a history of multiple cystine stones, and were on chronic fluid and alkalization therapy. Five patients had previously been on D-penicillamine. Cystine excretion studies were repeated 1 to 5 months after institution of captopril. Baseline 24-hour urinary cystine excretion ranged from 580 to 970 mg. per gm. creatinine (mean 744). After institution of captopril these levels decreased to a range of 113 to 581 mg. per gm. creatinine (mean 371). These values on treatment represented a statistically significant decrease to between 18 and 89% of baseline levels (p equals 0.0045). We conclude that captopril can significantly, and at times profoundly, decrease urinary cystine excretion in patients with homozygous cystinuria. Further studies are required to elucidate fully the mechanism of urinary cystine reduction and to help define a possible role for this drug in routine maintenance or dissolution therapy.

[A study of the risk factors in calcium oxalate stone formation--simple method for measuring metastable limits by the microplate method]

The stone forming urinary environment may be conducive to spontaneous nucleation of calcium oxalate, since it is generally characterized by a reduced metastable limit. This study indicates that the microplate method offers simple and reliable measures for estimating calcium oxalate's propensity for spontaneous nucleation. In measuring the metastable limit by the microplate method, 200 microliters aliquots of each urine sample were treated with sodium oxalate to give final concentrations of 0-1.5 mmol. The urine samples were then incubated at 37 degrees C for 20 min and the minimum amount of oxalate necessary to induce nucleation detectable by inverted microscopy was taken to be the measured metastable limit of each urine. The metastable limit by microplate method positively was correlated (p less than 0.001) with the metastable limit found by the Coulter counter method and inversely correlated (p less than 0.001) with the concentration product ratio. The metastable limits were significantly lower (p less than 0.001) in recurrent stone formers than in the control subjects. The metastable limit rose significantly (p less than 0.01) during treatment with thiazides. Moreover, the metastable limit was inversely correlated (p less than 0.01) with the stone episode rate. It is concluded that the metastable limits by the microplate method are useful in stone forming potential identification in urine as well as in the assessment of the response to the therapy.

Risk factors for urinary calcium oxalate crystals as revealed by their specific enzymatic assay

Calcium oxalate crystal concentrations were assayed by a new highly specific enzymatic method in 1200 urine samples from normal subjects and stone formers. Examination of the crystals was also carried out by light microscopy and urines were analysed for oxalate, calcium, magnesium, citrate, urate, pH and osmolality. A striking positive correlation was established between urinary oxalate concentration and calcium oxalate crystal concentration as well as incidence of calcium oxalate crystals and aggregates seen by microscopy. A less striking relationship, also supported by light microscopy, was found between calcium oxalate crystal concentration and urinary calcium concentration. A small rise in calcium oxalate crystalluria was seen with increasing osmolality, but no relationship found between concentration or urinary urate, citrate or magnesium and that of calcium oxalate crystals. Higher levels of calcium oxalate crystal concentration appeared in alkaline urines in association with calcium phosphates. The dominance of urinary oxalate as a risk factor for calcium oxalate crystalluria is confirmed.