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Biomedical subjects

G M Preminger

Publications and source records attributed to G M Preminger.

At least 127 records · Page 7Linked to original sources
PubMed1988

Alkali action on the urinary crystallization of calcium salts: contrasting responses to sodium citrate and potassium citrate.

Alkali therapy is used commonly to prevent recurrent stone formation in patients with distal renal tubular acidosis. We compared the effects of potassium citrate to those of sodium citrate in 6 well defined cases of incomplete distal renal tubular acidosis. The patients were studied during a control phase, during potassium citrate treatment (80 mEq. per day) and during sodium citrate treatment (80 mEq. per day) chosen in random order. Potassium citrate caused a decrease in urinary calcium and a significant increase in urinary citrate that resulted in a significant decrease in the urinary saturation of calcium oxalate. It did not alter the saturation of brushite and sodium urate. However, while sodium citrate also was able to increase the urinary citrate level, there was no decrease in the urinary calcium (owing to the increased sodium load). Thus, the urinary saturation of calcium oxalate did not decrease as much as with potassium citrate and the saturation of brushite increased significantly. Moreover, the urinary saturation of sodium urate increased significantly owing to the enhanced sodium excretion. The results suggest that potassium citrate therapy may retard the crystallization of calcium oxalate and may not cause calcium phosphate crystallization. In contrast, sodium citrate may have no effect or it sometimes may accentuate the crystallization of calcium salts. Thus, our study supports the potential clinical advantage of potassium citrate therapy over sodium alkali treatment in patients with incomplete distal renal tubular acidosis and recurrent calcium nephrolithiasis.

Acidosis, Renal Tubular↗
PubMed1988

Urinary glycosaminoglycans in normal subjects and patients with stones.

Urinary glycosaminoglycans are thought to be macromolecular inhibitors of calcium stone formation. The 24-hour excretion of urinary glycosaminoglycans was measured quantitatively in 24 normal subjects and 206 patients with different etiologies of stone disease. In both groups a positive correlation was found between urinary glycosaminoglycans and total urinary volume and urinary sulfate. In normal subjects total urinary volume was r equals 0.716, p less than 0.001 and urinary sulfate was r equals 0.813, p less than 0.001, while in patients with stones these values were r equals 0.338, p less than 0.001 and r equals 0.326, p less than 0.001, respectively. The only significant difference in excretion of urinary glycosaminoglycans between the groups was found in the subgroup of patients with type I absorptive hypercalciuria. The type I absorptive hypercalciuria value of 33.4 +/- 14.9 mg. per day in patients with stones was significantly higher than the 25.8 +/- 8.3 mg. per day detected in normal subjects (p less than 0.05). Urinary glycosaminoglycan excretion in all other subgroups of nephrolithiasis as well as in a combined group of all patients with stones showed no significant difference when compared to that of normal subjects. Thus, no major quantitative relationship could be demonstrated between urinary glycosaminoglycan excretion and calcium stone formation in this study.

Adult↗
PubMed1988

Treatment of ureteral calculi by extracorporeal shock wave lithotripsy at a multi-use center.

We reviewed our experience with extracorporeal shock wave lithotripsy therapy in 138 patients who presented with mid and upper ureteral calculi. In the patients who had successful stone manipulation back into the renal collecting system the success rate was significantly higher compared to that for stones treated primarily within the ureter (92.8 versus 80.8 per cent, p less than 0.05). Among the stones treated within the ureter the success rates appeared to be similar for stones treated in situ (83.3 per cent) compared to those treated when a catheter could be placed alongside the calculus (79.3 per cent). Higher voltage and more shock waves were administered to stones treated within the ureter compared to stones that were manipulated back into the kidney. However, this increase power did not enhance the success rate. In addition, it appears that a plain film of the abdomen obtained within 24 hours of lithotripsy treatment is a good predictor of success as defined by the rate free of stones at 6 weeks of followup. Our results from a community-based multi-use lithotripsy center suggest that ureteral stone manipulation should be attempted before extracorporeal shock wave lithotripsy for mid and upper ureteral calculi.

Health Facilities↗
PubMed1988

Changing surgical aspects of urinary stone disease.

Surgical management of urinary calculous disease has changed dramatically in the past decade. The development of percutaneous nephrostomy techniques has allowed new access to upper tract stones. Percutaneous removal of large calculi was made possible by the development of ultrasonic and electrohydraulic lithotripsy. All upper tract calculi can now be removed in 70 to 100 per cent of cases with minimal complications. Nephrostolithotomy has reduced transfusion rates and hospitalization costs and has markedly shortened convalescence periods compared with open surgery. Ureteroscopy followed nephrostolithotomy as advanced fiberoptic technology allowed the development of the small-caliber instruments required for this procedure. With experience, successful stone retrieval has occurred in 90 per cent or more of cases, again with minimal complications. As nephrostolithotomy and ureteroscopy have become available, the subspecialty of endourology has emerged and significantly changed the management of urinary tract calculi. Perhaps the most significant advance in stone therapy has been the design and implementation of extracorporeal shock wave lithotripsy. With this noninvasive technique, most renal and proximal ureteral calculi can be effectively treated with minimal morbidity and convalescence. Research in lithotripter design is continuing, with more advanced and effective machines on the horizon. The applicability of extracorporeal therapy for the treatment of biliary tract calculi is currently under investigation. Finally, one should not disparage medical therapy for recurrent nephrolithiasis. A comprehensive metabolic evaluation combined with selective medical therapy provides almost complete relief from recurrent stone formation and makes medical therapy an integral component of treating the patient with renal or ureteral calculi.

Endoscopy↗
PubMed1988

Flexible cystoscopy.

Flexible fiberoptic technology was first applied to cystoscopy in 1973, with greatly increased usage since 1982. Most procedures formerly performed with rigid cystoscopes can be done using flexible cystoscopes with minimal or no anesthesia. Patient positioning and precystocopy preparation and draping are simplified with the flexible fiberoptic instruments. Complete examination of the urethra and bladder can be performed with a single-lens system and with the patient in a variety of positions. Fiberoptic cystoscopy is limited in patients who are bleeding or have blood clots in their bladders. Withdrawal of irrigant or bladder drainage is cumbersome, and the fiberoptic image is currently not of the same caliber as that of the rigid-lens systems. Fiberoptic cystoscopy has become the procedure of choice for many urologists for ureteral stenting prior to extracorporeal shock-wave lithotripsy. With the advent of lithotripters that require no anesthesia, this application is likely to broaden. Future applications of flexible cystoscopy may include a flexible videocystoscope for use in diagnostic and therapeutic procedures.

Cystoscopes↗
PubMed1987

Hypercalciuria and altered intestinal calcium absorption occurring independently of vitamin D in incomplete distal renal tubular acidosis.

Negative calcium balance and calcium nephrolithiasis are two sequelae of chronic metabolic acidosis. To establish the effects of acidosis on calcium and vitamin D metabolism, we have examined a group of nine patients with incomplete distal renal tubular acidosis. Patients were studied during a control phase and after eight months of potassium citrate treatment, 60 to 80 meq daily. Potassium citrate caused a significant decrease in urinary calcium. The fractional intestinal calcium absorption increased significantly, yet no change was observed in serum vitamin D levels. The estimated calcium balance increased significantly from -70.2 +/- 63.8 to +66.7 +/- 48.7 mg/d (P less than 0.01). Thus, potassium citrate treatment improved the estimated calcium balance by lowering urinary calcium while increasing the fractional intestinal calcium absorption. The original hypercalciuric state, its correction to normocalciuria, and the augmentation of intestinal calcium absorption seen in these patients are probably independent of vitamin D control since there was no change noted in serum 1,25-dihydroxyvitamin D levels.

Acidosis, Renal Tubular↗
PubMed1987

Cephalad renal movement during percutaneous nephrostolithotomy.

The change in the position of the kidney during percutaneous nephrostomy is a major concern to urologists who participate in percutaneous stone removal. We report that the majority of kidneys ascend an average of 2.2 cm. when the patient turns from a supine to a prone position. This change in position is more marked on the right side and is more common in male patients. Knowledge of this anatomical variation is important to determine which patients are suitable candidates for percutaneous nephrostolithotomy and to plan a percutaneous approach to a renal or ureteral calculus.

Adult↗
PubMed1987

Eventual attenuation of hypocalciuric response to hydrochlorothiazide in absorptive hypercalciuria.

The effect of long-term hydrochlorothiazide therapy on renal calcium excretion was measured in 12 well defined cases of absorptive hypercalciuria and 10 of renal hypercalciuria. Patients were studied during a control phase, at 3 to 6 months of therapy and after long-term treatment with hydrochlorothiazide (mean 61 months for absorptive hypercalciuria and 71 months for renal hypercalciuria). Evaluation comprised measurement of urinary calcium and fractional (intestinal) calcium absorption while patients were maintained on a constant metabolic diet (400 mg. calcium per day) for 3 days. In patients with absorptive hypercalciuria urinary calcium decreased significantly at 3 months of treatment (from 266 to 137 mg. per day, p less than 0.001). However, with continued treatment urinary calcium rebounded to 197 mg. per day. Of the patients with absorptive hypercalciuria 50 per cent were hypercalciuric (greater than 200 mg. per day) on long-term treatment, whereas none was hypercalciuric at 3 months. In contrast, urinary calcium in the patients with renal hypercalciuria decreased from 299 to 104 mg. per day (p less than 0.001) at 3 months of treatment and remained reduced (116 mg. per day) during long-term treatment. Intestinal calcium absorption was increased initially and remained unchanged throughout treatment in the patients with absorptive hypercalciuria. In patients with renal hypercalciuria intestinal calcium absorption decreased significantly after short-term treatment with hydrochlorothiazide and remained so after long-term therapy. The results suggest that, unlike patients with renal hypercalciuria, some with absorptive hypercalciuria lose the hypocalciuric effect of hydrochlorothiazide during long-term treatment.

Adult↗
PubMed1987

Pharmacologic treatment of calcium calculi.

Selective pharmacologic therapy of calcium nephrolithiasis is highly effective in preventing new stone formation. A remission rate of greater than 80 per cent and overall reduction in individual stone formation rate of greater than 90 per cent can be obtained in patients with calcium nephrolithiasis. In patients with mild-to-moderate severity of stone disease, virtually total control of stone disease can be achieved as evidenced by remission rates of greater than 95 per cent. The need for stone removal may be dramatically reduced by an effective prophylactic program. Selective pharmacologic therapy of calcium nephrolithiasis also encompasses the advantages of overcoming the nonrenal manifestations of conditions that cause stone formation as well as averting certain side effects that may be caused by nonselective medical therapy. Despite these advantages, selective medical therapy clearly cannot provide total control of stone disease. A satisfactory response requires continued, dedicated compliance by patients to the recommended program and a commitment of the physician to provide long-term follow-up and care.

Benzothiadiazines↗
PubMed1987

Pharmacologic treatment of uric acid calculi.

Uric acid stone disease is dependent on three pathogenetic factors: acid urine pH, low urine volume, and hyperuricosuria. The management of nonobstructing uric acid calculi should include maintenance of an alkaline urine, an increase in urine volume, and reduction in urinary uric acid excretion. It appears that potassium alkali may avoid the complication of calcium stone formation in patients with uric acid stones. In patients with obstructing uric acid calculi, more rapid dissolution may be accomplished with intravenous alkalinization or direct irrigation of the stone with an alkaline solution.

Allopurinol↗
PubMed1986

Outpatient percutaneous nephrostolithotomy.

Technical advances and operator experience have resulted in a rapid and marked streamlining of the percutaneous approach to renal calculi. The development of nephrostomy tract balloon dilators, improved grasping instruments and the use of assisted local anesthesia have been integral in reducing the morbidity and cost of the procedure. We report our initial favorable experience in the use of percutaneous stone removal on an outpatient basis. All 5 patients underwent an uncomplicated 1-stage stone removal. Cost for outpatient percutaneous stone removal was substantially less than for surgery or extracorporeal shock wave lithotripsy.

Adult↗
PubMed1985

Male urethral diverticulum: the double density sign.

An anatomic defect of the urethra is occasionally the cause of voiding dysfunction in the young male patient. A urethral diverticulum can often be overlooked if retrograde urethrography is not performed properly. Two cases are presented along with a discussion of the technique for dynamic retrograde urethrography. The description of a new radiologic sign indicative of a posterior bulbar urethral diverticulum, is presented.

Adult↗
PubMed1985

The current role of medical treatment of nephrolithiasis: the impact of improved techniques of stone removal.

To document more clearly the effect of selective medical treatment on the course of nephrolithiasis, we surveyed 103 consecutive patients being followed in our stone clinic. Of the patients who initially had existing stones within the kidneys 69 per cent experienced no symptoms while undergoing medical therapy, compared to 96 per cent of those who had no existing stones. In all subjects studied new stone formation was reduced in more than 95 per cent and no new stones were formed in more than 75 per cent. An operation for newly formed calculi was necessary in only 2 per cent of the patients on medical therapy, whereas 58 to 69 per cent of the patients required an operation for new stones before beginning medical treatment. We believe that selective medical treatment has an important role in the over-all management of nephrolithiasis. Appropriate medical therapy may decrease significantly the number of new stones formed and may obviate the need for a repeat stone operation. Therefore, medical treatment should be an important adjunct to percutaneous nephrostolithotomy and extracorporeal shock wave lithotripsy.

Adult↗
PubMed1985

Long-term treatment of calcium nephrolithiasis with potassium citrate.

The long-term effects of potassium citrate therapy (usually 20 mEq. 3 times daily during 1 to 4.33 years) were examined in 89 patients with hypocitraturic calcium nephrolithiasis or uric acid lithiasis, with or without calcium nephrolithiasis. Hypocitraturia caused by renal tubular acidosis or chronic diarrheal syndrome was associated with other metabolic abnormalities, such as hypercalciuria or hyperuricosuria, or occurred alone. Potassium citrate therapy caused a sustained increase in urinary pH and potassium, and restored urinary citrate to normal levels. No substantial or significant changes occurred in urinary uric acid, oxalate, sodium or phosphorus levels, or total volume. Owing to these physiological changes, uric acid solubility increased, urinary saturation of calcium oxalate decreased and the propensity for spontaneous nucleation of calcium oxalate was reduced to normal. Therefore, the physicochemical environment of urine following treatment became less conducive to the crystallization of calcium oxalate or uric acid, since it stimulated that of normal subjects without stones. Commensurate with the aforementioned physiological and physicochemical changes the treatment produced clinical improvement, since individual stone formation decreased in 97.8 per cent of the patients, remission was obtained in 79.8 per cent and the need for surgical treatment of newly formed stones was eliminated. In patients with relapse after other treatment, such as thiazide, the addition of potassium citrate induced clinical improvement. Thus, our study provides physiological, physicochemical and clinical validation for the use of potassium citrate in the treatment of hypocitraturic calcium nephrolithiasis and uric acid lithiasis with or without calcium nephrolithiasis.

Adult↗
PubMed1985

Prevention of recurrent calcium stone formation with potassium citrate therapy in patients with distal renal tubular acidosis.

Distal renal tubular acidosis is a common cause of intractable calcium nephrolithiasis. We examined the effect of oral potassium citrate therapy in 9 patients with incomplete distal renal tubular acidosis diagnosed on the basis of an abnormal response to an oral ammonium chloride load. Patients were studied during a control phase and after 3 months of potassium citrate treatment (60 to 80 mEq. daily). Potassium citrate caused a significant increase in urinary pH and urinary citrate, and a decrease in urinary calcium. The urinary relative saturation ratio of calcium oxalate significantly decreased during treatment, while that of brushite did not change. Potassium citrate also was shown to inhibit new stone formation. During a mean treatment period of 34 months none of the 9 patients had new stones, although 39.3 plus or minus 79.7 (standard deviation) stones per patient formed during the 3 years preceding treatment. The results support the potential clinical advantage of potassium citrate therapy in patients with distal renal tubular acidosis and recurrent calcium nephrolithiasis.

Acidosis, Renal Tubular↗
PubMed1985

Comparative efficacy of "specific" potassium citrate therapy versus conservative management in nephrolithiasis of mild to moderate severity.

It generally is believed that conservative measures of high fluid intake and dietary modification in the setting of a stone clinic could favorably influence the course of renal stone disease. To establish the effect of specific medical treatment from the stone clinic effect, we compared the results of potassium citrate therapy to those of 11 reported conservative or placebo trials. The 54 patients receiving potassium citrate chosen for this comparison had mild to moderately severe stone disease (less than 1 stone per patient per year), similar to that encountered in conservative placebo trials (mean 0.54 stones per patient per year). New stone formation was virtually eliminated by potassium citrate therapy (a decrease from 0.52 to 0.02 stones per patient per year, a remission rate of 96 per cent, p less than 0.001), whereas it continued in 39 per cent of the patients during conservative or placebo trials. However, in patients participating in conservative or placebo trials new stone formation decreased by only 54 per cent (from 0.54 to 0.25 stones per patient per year). The superior response to potassium citrate suggested that this specific medical treatment exerted an additional favorable effect on the course of stone disease above the stone clinic effect.

Citrates↗