Search

Eighty-three patients with radiographically opaque renal stones were evaluated prospectively with ultrasound and compared to KUB (kidneys, ureters, bladder) with tomograms (KUB/T) to further define the use of ultrasound in the evaluation of renal calculi. The presence or absence and the size, number, and location of stones were analyzed and correlated for each modality. Ultrasound detected the presence of renal stones in 77 of 83 (93%) patients. However, all of the stones were detected on ultrasound in only 60% of these patients. Thirty percent (80 of 269) of the papillary-calyceal stones seen on KUB/T were missed on US; 66% of the stones missed measured 2 mm or less. Although ultrasound can be used for detection of intrarenal stones, KUB/T is a more accurate imaging examination for determination of size and number of small stones.

Nine women with laxative abuse and predominantly ammonium urate renal calculi underwent metabolic studies to identify common chemical abnormalities and determine pathophysiology. The 24-hour urine studies demonstrated marked decreases in volume (902 cm.3), sodium (28 mEq.), citrate (116 mg.) and potassium (21 mEq.). A significant elevation in ammonium urate supersaturation was found compared to control subjects when studied by the computer model EQUIL 2. Of the patients 7 had 1 or more urine specimens positive for phenolphthalein. Gastrointestinal loss of fluid and electrolytes allowed for chronic extracellular volume depletion. Intracellular acidosis was present as judged by low urinary citrate and potassium. The fact that the ion product for ammonium urate is increased significantly compared to controls reflects the stated pathophysiological changes. Laxative abuse should be suspected whenever a woman has an ammonium urate renal calculus in sterile urine.

Despite the frequency and morbidity of nephrolithiasis in autosomal dominant polycystic kidney disease (ADPKD), this association has not been subject to a detailed study. One hundred fifty-one of 751 ADPKD patients seen at the Mayo Clinic between 1976 and 1986 had nephrolithiasis. Seventy-four had passed calculi or had stones surgically removed. Stone analysis was available in 30 patients: uric acid, calcium oxalate, calcium phosphate, and struvite were present in 56.6%, 46.6%, 20%, and 10%, respectively. Calculi were observed in 71 of 79 patients with excretory urograms available for review. Faintly opaque and bull's eye stones, probably containing uric acid, were present in 12.7% and 14.1% of these patients, respectively. Precaliceal tubular ectasia was observed in 15.5%. Ninety-seven patients had preserved renal function (serum creatinine less than 1.5 mg/dL) at the initial evaluation. Six were excluded because they had other known causes of stone disease. The most common metabolic abnormality in the remaining 91 patients was hypocitric aciduria (ten of 15 patients with measurements). The urine pH in the first voided morning specimens (5.66 +/- 0.05) was significantly lower than that of an unselected control population (5.92 +/- 0.03, P less than 0.001). Hyperuricosuria, hyperoxaluria, and hypercalciuria were observed in six of 32 (18.8%), six of 31 (19.4%), and three of 39 (9.7%) patients with preserved renal function. The composition of the stones, the frequency of hypocitric aciduria, and the low urine pH (possibly related to the defect in excretion of ammonia described in ADPKD), suggest that metabolic, along with mechanical, factors are responsible for the frequent occurrence of nephrolithiasis in this disease.

We report on a patient in whom 3 large renal calculi formed within 12 weeks after pyeloplasty. Subsequently, a parathyroid adenoma was found. This report illustrates the need to evaluate thoroughly a patient with borderline elevation of serum calcium before renal surgery. Current research indicates that primary hyperparathyroidism is more prevalent than thought previously. A majority of patients with primary hyperparathyroidism have mild asymptomatic disease detected solely by routine serum chemistry screening tests.

A patient with regional enteritis and recurrent uric acid nephrolithiasis was treated with allopurinol. While on 600 mg of allopurinol daily, she began to pass many small, soft, yellow stones. Analysis of the stones by liquid chromatographic and gas chromatograph/mass spectrometric techniques revealed that their major constituent was oxypurinol, a metabolite of allopurinol. Metabolic studies of the patient indicated that increasing doses of allopurinol were associated with increases in xanthine and oxypurinol excretion, while uric acid excretion was not reduced. This case illustrates a complication of high-dose allopurinol therapy in the treatment of uric acid nephrolithiasis.

The process of stone formation within the urinary tract involves multiple etiologic factors. Metabolic and/or ion transport abnormalities, either primary or secondary, provide relative solute excess. Multiple changes in the physical chemistry of the urine follow, leading to crystal formation and the potential for stones to occur. The states of saturation, sites and mechanism of crystal retention, and modifiers of crystal formation influence directly this process. In the evaluation of a patient with stones, etiologic factors, be they in the areas of metabolism, ion transport or physical chemistry should be identified. Treatment is then designed to correct these specific abnormalities. The remainder of this article will be devoted to considerations of these principles.

We have performed percutaneous extractions of renal pelvic stones in 194 patients via the Wolf percutaneous universal nephroscope. At 1 session, with the patient under general anesthesia, a percutaneous tract is dilated to 24F and the stone is removed immediately. We have removed 185 stones successfully by ultrasonic lithotripsy, basket retrieval and/or use of forceps. Average operating time was 54 minutes and mean hospitalization was 5 days. The advantages of this technique are that a skin incision of only 1 cm. is required to remove the stone, hospital days are fewer than with open procedures and postoperative morbidity is minimal. In selected situations this method represents a significant advance over standard open surgical procedures for removal of renal pelvic stones.

A BASIC computer program for the calculation of urinary supersaturation with respect to the common kidney stone components is described. In vitro and in vivo tests show that the program described accurately calculates supersaturation. The application of this computer program to urolithiasis research is discussed.

The commonly used diuretic Tri and its metabolites have been identified recently as major components of some kidney stones. We have carried out basic physical chemical studies to determine the mechanism of Tri incorporation into kidney stones. The solubility and pK of Tri and its major metabolites, Tri-OH and the Tri-So4, have been determined at 37 C in 0.15 M NaCl. The effect of Tri and its metabolites on crystal formation has been measured in the calcium oxalate monohydrate, hydroxyapatite, and uric acid crystal systems. Tri and its metabolites do not promote crystal nucleation, growth, or aggregation in any of these crystal systems and are not incorporated as these crystals form. We can demonstrate binding of Tri and its metabolites to the protein matrix isolated from kidney stones. These data suggest that Tri and its metabolites to the protein matrix isolated from kidney stones. These data suggest that Tri and its metabolites do not promote the formation of kidney stones but rather become incorporated into existing stones or stone nidi by binding to the protein matrix found in all kidney stones.