A RETROSPECTIVE STUDY OF UPPER URINARY TRACT CALCULI

Amperometric determination of oxalate in plasma and urine by liquid chromatography with immobilized oxalate oxidase

A detection system for plasma and urinary oxalate involving a postcolumn enzymatic reaction and electrochemical detection is described. Oxalate oxidase was immobilized on AF-Tresyl Toyopearl 650 gel. The immobilized oxalate oxidase was packed into a stainless-steel column (10 x 4 mm I.D.) and used on-line as an immobilized enzyme reactor (IMER). The hydrogen peroxide produced by enzymatic reaction was detected amperometrically at a platinum electrode maintained at +0.5 V vs. Ag/AgCl. The HPLC separation of oxalate was carried out using a Capcell Pak C8 column and an isocratic mobile phase containing 80 mM KH2PO4 and 5 mM tetra-n-butylmammonium phosphate as an ion-pair reagent. The IMER was active and stable in the mobile phase employed. The plot of peak height against concentration of oxalate was linear in the range 0.1-1.6 mumol/ml with a correlation coefficient of 0.9989. The detection limit was 10 nmol/ml at a signal-to-noise ratio of 3. The within-day and between-day coefficients of variation were 5.3 and 7.9%, respectively.

Impact of shockwave lithotripsy on upper urinary tract calculi

Extracorporeal shock wave lithotripsy (ESWL) currently is performed in selected urologic centers to treat over 80 per cent of patients with symptomatic upper urinary tract calculi. This noninvasive technique utilizing shockwaves to disintegrate stones into sand-sized particles allows the patient to pass the particles with spontaneous urination and replaces most surgery or percutaneous endoscopy for stone removal. However, stone-free success rates must be individualized depending on stone position, stone size, and composition. Lithotripsy of renal stones prior to migration and proximal ureteral stones early in their symptomatic course may alter significantly the incidence of distal ureteral calculi requiring hospitalization, cystoscopy, or ureteroscopy.

Specific and rapid assay of urinary oxalic acid using high-performance liquid chromatography

A high-performance liquid chromatographic (HPLC) method was developed to determine the levels of oxalic acid in the urine. This acid was extracted from urine with tri-n-butyl phosphate and converted into the fluorescent derivative by esterification with 9-anthryldiazomethane (ADAM). The reaction mixture containing the oxalic acid derivative can be directly chromatographed on HPLC using octadecylsilane reverse-phase column monitoring with a fluorophotometric detector. A linear relationship was observed in the range from 1 to 100 micrograms/ml of standard oxalic acid dissolved in saline. Disease-free Japanese adults excrete 23.8 +/- 9.0 mg (mean +/- SD) of oxalic acid per day. This method should prove valuable for routine measurements of urinary oxalic acid as it is accurate, simple, and specific.

A review of 171 consecutive patients with urinary lithiasis

During a 3-year interval 171 patients with urinary tract calculi were seen and studied: 98 had kidney, 52 had ureteral and 21 had bladder calculi. In 54 of the 98 patients with kidney stones (55 per cent) abnormal elevations of the blood and/or urine calcium, uric acid or creatinine were noted. Of these 98 patients 54 (55 per cent) were treated with observation only, 42 (43 per cent) were treated surgically (with an operative mortality of 2.4 per cent) and in 2 the renal stones passed spontaneously. Sixty-two per cent of the patients with renal calculi had a history of stones. It is believed that asymptomatic renal stones located in a calix or calices and not associated with infection are best managed nonoperatively. The average age of the 52 patients presenting with ureteral calculi was 12 years younger than that of patients presenting with renal calculi (36 versus 48 years). In 46 per cent of these cases the ureteral calculi ultimately passed spontaneously. Conservative therapy of ureteral calculi with long-term expectant observation (weeks and even months) often is indicated in the obstructed and uninfected patient. Twenty-nine per cent of the patients with ureteral calculi had a history of stones.

Pattern of urolithiasis in Brooklyn, New York

Crystallographic analysis of 261 upper urinary tract calculi from patients in Brooklyn is presented. Calcium oxalate, uric acid, and struvite stones predominate. We could not confirm the hypothesis that uric acid forms a nidus in calcium oxalate urolithiasis in spite of a percentage of uric acid calculi more than twice the national average.

Prevalence rate of renal stone disease in Forsyth County, North Carolina during 1977

A count of all recorded hospitalized cases of Forsyth County, North Carolina residents with a primary discharge diagnosis of renal (kidneyand/or ureteral) stone in 1977 is obtained by age, race and sex, and used in conjunction with the census data to estimate age-adjusted prevalence rates. The over-all prevalence rate is 2.08 per thousand population, which agrees well with results of earlier investigations. For white male subjects the age-adjusted prevalence rate is 3.64 per thousand, for white female subjects 1.44, for non-white male subjects 0.97 and for non-white female subjects 0.34. The white to non-white ratio and the male to female rates are compared with earlier published values. For all groups the prevalence rate increases with age, attaining a maximum in the 40 to 60-year category for whites and somewhat later for non-whites. Beyond age 60 prevalence drops, reaching 0 or near 0 in the 80 to 89-year range. A simple phenomenological model is suggested to explain the observed race and sex differences in the prevalence rates.

Relation of spontaneous passage of ureteral calculi to size

A statistical analysis of 520 ureteral calculi was undertaken to elucidate the correlation between sizes of calculi and the probability of spontaneous passage. The mean length and width of 286 calculi passed spontaneously were 6.3 +/- 2.5 (S.D.) and 4.0 +/- 1.5 mm., respectively; those of 219 calculi removed surgically were 11.7 +/- 5.0 and 7.1 +/- 2.8 mm., respectively, the difference between the two groups being statistically significant. The rate of spontaneous passage of stones within one year after diagnosis was analyzed in relation to sizes of stones which were grouped at successive 1-mm. intervals both in length and width, the over-all rate of spontaneous passage being 53 per cent. It was concluded that stones larger than 8 mm. in width on x-ray films should be removed surgically, while in those smaller than 8 mm. in width higher chances of spontaneous passage by expectant treatment would be anticipated.

Ureteropelvic junction obstruction in nephrolithiasis. An etiologic factor

Obstruction is rarely accepted as the sole cause of calculi. We have reviewed 106 cases of nephrolithiasis for which surgery was performed at the St. Luke's Hospital Center during the past ten years. In 17 of these cases, obstruction of the ureteropelvic junction was demonstrated, an incidence of 16 per cent. We propose the theory that too frequently the responsible ureteropelvic junction obstruction goes undetected when a "routine" pyelolithotomy or nephrolithotomy is performed.