Lynwood H. Smith

EQUIL2: a BASIC computer program for the calculation of urinary saturation.

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.

Acquired Hyperoxaluria, Nephrolithiasis, and Intestinal Disease: Description of a Syndrome

Abstract In seven patients with resection of the distal ileum, calcium oxalate nephrolithiasis and increased urinary excretion of oxalate (64 to 135 mg per 24 hours) developed. Cholestyramine therapy (4 g four times a day) lowered the 24-hour urinary excretion of oxalate to normal in the four patients in whom it was used. Urinary excretion of oxalate was measured in an additional 42 patients with various types of intestinal disorders without evidence of nephrolithiasis. Five of 18 patients with ileal resection, two of seven with bacterial over-growth, and six of 15 with miscellaneous conditions, including nontropical sprue and cirrhosis, had hyperoxaluria.

Acquired Hyperoxaluria, Nephrolithiasis, and Intestinal Disease

Abstract In seven patients with resection of the distal ileum, calcium oxalate nephrolithiasis and increased urinary excretion of oxalate (64 to 135 mg per 24 hours) developed. Cholestyramine therapy (4 g four times a day) lowered the 24-hour urinary excretion of oxalate to normal in the four patients in whom it was used. Urinary excretion of oxalate was measured in an additional 42 patients with various types of intestinal disorders without evidence of nephrolithiasis. Five of 18 patients with ileal resection, two of seven with bacterial over-growth, and six of 15 with miscellaneous conditions, including nontropical sprue and cirrhosis, had hyperoxaluria.

Results of Long-Term Treatment with Orthophosphate and Pyridoxine in Patients with Primary Hyperoxaluria

Background The prognosis for patients with primary hyperoxaluria has been ominous, with the expectation of renal failure, poor results with transplantation, and early death. Methods We studied the long-term effects of orthophosphate and pyridoxine therapy in 25 patients with primary hyperoxaluria who were treated for an average of 10 years (range, 0.3 to 26). Their mean age at the start of treatment was 12 years (median, 6; range, 0.5 to 32). We also studied the effect of orthophosphate and pyridoxine on urinary supersaturation with calcium oxalate, crystal inhibition using a seeded growth system, and crystal formation using scanning electron microscopy in 12 patients during three-day stays in the clinical research center. Results The mean (±SD) glomerular filtration rate at the start of treatment was 91 ±26 ml per minute per 1.73 m2. The median decline in glomerular filtration rates was 1.4 ml per minute per 1.73 m2 of body-surface area per year. The actuarial survival free of end-stage renal disease was...

The Association of Nephrolithiasis and Autosomal Dominant Polycystic Kidney Disease

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 bulls 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.

The Medical Aspects of Urolithiasis: An Overview

An overview of the medical aspects of urolithiasis is presented. The physicochemical factors in the formation of a stone within the urinary tract are reviewed, including supersaturation, nucleation sites and mechanisms of crystal formation and retention, and modifiers of crystal formation, including promoters and inhibitors. Finally, some directions for future research in urolithiasis are identified.

Laxative Abuse as a Cause for Ammonium-Urate Renal Calculi

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.

Nutrition and urolithiasis.

FORMATION of stones within the urinary tract is a complication of many varied metabolic disorders.1 The nutritional aspects of urolithiasis, especially if one includes fluid intake, are important i...

Long-term followup in patients with cystine urinary calculi treated by percutaneous ultrasonic lithotripsy

From February 1983 through 1986, 15 patients (17 renal units) with cystine urinary lithiasis were treated by percutaneous ultrasonic lithotripsy. Three patients were lost to followup. Of the 13 renal units in the remaining 12 patients 7 (54 per cent) had retained stone fragments and 6 (46 per cent) were free of stones. While on medical management 7 of the 13 renal units (54 per cent) had new stones, 5 (38 per cent) remained unchanged and in 1 (8 per cent) the retained stones dissolved. The rate for reoperations was 43 per cent for the group with retained stones (3 of 7) and 17 per cent for the group that was free of calculi after percutaneous ultrasonic lithotripsy (1 of 6). Our study suggests that the optimal treatment with percutaneous ultrasonic lithotripsy should result in a patient who is free of stones.

Diagnosis of primary hyperparathyroidism.

A diagnosis is established by elevation of serum calcium on repeated determinations in the absence of other disease states or medications known to increase serum calcium. Determination of serum immunoreactive parathyroid hormone is valuable in the differential diagnosis of hypercalcemia.