Lasse Larsson

Variations in urine composition during the day in patients with calcium oxalate stone disease.

The diurnal variations of urine composition with respect to calcium, magnesium, oxalate, citrate and inhibition of calcium oxalate crystal growth were studied in patients with recurrent calcium oxalate stone disease. There was considerable variation in the excretion of the different urine constituents with meal-related peaks, which was most pronounced for calcium. The highest concentration of calcium was observed before noon, and between 7 and 11 p.m. Oxalate concentration was highest between 6 and 10 a.m. Consequently, the highest levels of supersaturation were recorded between 6 and 10 a.m., and 6 and 10 p.m. The inhibition index was at the highest level during the first morning hours and could be important in counteracting crystal growth at that time. The risk of exceeding a theoretical formation product of calcium oxalate appeared to be low, with a 24-hour urine volume more than 2,000 ml.

Oxalate metabolism after intestinal bypass operations.

Hyperoxaluria and kidney stones are frequent following intestinal bypass operations. The urinary oxalate excretion was studied for 10-13 days during enteral and parenteral nutrition in six patients operated on because of massive obesity with a jejunoileostomy. The oxalate excretion in urine was higher than normal in all patients on normal diet. The excretion decreased on low-oxalate diet. Further decrease was observed during total parenteral nutrition (TPN). The oxalate excretion was stabilized at a low level within 48 h after the start of TPN and was unchanged during the rest of the study. This included a period of 2 days when a load of the oxalate precursor glycine (10 and 20 g) was given parenterally to five patients, resulting in increased serum glycine concentration. A slight decrease in oxalate excretion was found when the amino acid part (Vamin with 10% glucose) of the TPN solution was given enterally instead of parenterally in two patients. This study has indicated that the main reason for hyperoxaluria in patients with intestinal bypass operations is hyperabsorption of dietary oxalate. It seems likely that these patients have a normal endogenous oxalate production.

Factors Influencing the Time Long-Term Indwelling Foley Catheters Can Be Kept in situ

To study the factors that influence the frequency of unscheduled catheter changes, patients with long-term indwelling Foley catheters were followed up for 48 weeks. A marked interindividual difference in the need for unscheduled changes was noted. The amount and composition of the encrustations precipitated on the catheters and urine osmolality influenced the frequency of unscheduled catheter changes. There was no correlation between the time a catheter had been in situ and the amount of encrustations on catheters changed on schedule after various times in situ. This indicates that time does not govern the amount of encrustations accumulated.

Urine composition following jejunoileal bypass.

The urinary excretion of oxalate, calcium, citrate, magnesium, urate and creatinine and the inhibition of calcium oxalate crystal growth were determined in 30 patients operated with three different types of jejunoileal bypass. In addition the ion-activity products of calcium oxalate and calcium oxalate saturation were calculated. 15 of the patients had formed urolithiasis postoperatively. The patients were investigated on an out-patient basis with their ordinary diet. All patients had hyperoxaluria. The oxalate excretion did not seem to decrease with time after operation. The patients operated with a biliointestinal shunt had a significantly higher excretion of oxalate than those with the other two types of operation, indicating that variations in the anatomy of the small intestine after jejunoileal bypass might result in different absorption of oxalate or oxalate precursors. Urinary oxalate, calcium oxalate saturation and ion-activity products were higher whereas the excretion of calcium, magnesium and citrate was lower in patients than in controls. The urine volumes, excretion of creatinine and urate and inhibition of calcium oxalate crystal growth were equal in patients and controls. Analogous urine composition was found in patients both with and without urolithiasis with the exception of a higher magnesium excretion observed in stone formers.

Inhibition of Calcium Oxalate Crystal Growth in Patients with Urolithiasis

It is now generally accepted that the formation of calcium oxalate stones occurs in urine which is supersaturated with respect to calcium oxalate1. Formation, growth and aggregation of calcium oxalate crystals are modified by urinary inhibitors. Information on the activity of these inhibitors are of importance when estimating the risk of renal stone formation2.

Oxalate Metabolism in Man Studied During Total Parenteral Nutrition

The mean urinary excretion of oxalate was 325 micromol/24 h in six patients during total parenteral nutrition (TPN). The urinary excretion of oxalate was considered to be equal to the endogenous oxalate production. A 2-day load of the oxalate precursor glycine given to five patients did not influence the oxalate excretion in spite of increased serum glycine concentrations. A 3-day load of the oxalate precursor ascorbic acid given to four patients increased the oxalate excretion in all patients. In one patient TPN was prolonged for 20 days without any change in the amount of oxalate excreted.

The Influence of Gastrointestinal Anatomy on Oxalate Excretion and Kidney Stone Incidence in Patients with Enteric Hyperoxaluria

Jejunoileal bypass operations result in malabsorption with diarrhea, especially during the first postoperative year. Hyperoxaluria and increased risk of forming renal calculi have been found in these patients1,2.

Dietary Treatment of Hyperoxaluria Following Jejunoileal Bypass

Hyperoxaluria is a common consequence of intestinal resection1 and jejunoileal bypass operations2. It may result in renal failure due to oxalosis3. High intestinal absorption of oxalate is thought to be responsible for the hyperoxaluria4,5. Peroral supplementation with calcium reduces the degree of hyperoxaluria under “metabolic ward” conditions6,7. In patients living at home, however, the effect seems to be doubtful8. Diets low in oxalate9 and fat4 likewise decrease oxalate excretion under metabolic ward conditions. Little is known of the effect of such diets under outpatient conditions. The aim of the present investigation was to observe the effect of low-oxalate, low-fat diet on the urinary excretion of oxalate in patients with hyperoxaluria following jejunoileal bypass living at home.

Treatment of Hyperoxaluria in Patients with Jejunoileal Bypass: Effects of Calcium, Aluminum, Magnesium and Cholestyramine

Hyperoxaluria and calcium oxalate stones are common following intestinal resection1 and jejunoileal bypass operations2,3. A high intestinal absorption of oxalate appears to be responsible for the hyperoxaluria4,5. Diets low in oxalate5 and fat4 have been recommended to reduce oxalate excretion, but may be difficult to adhere to because of unpalatability6. Oral administration of calcium7, aluminium6, magnesium8 and cholestyramine9 have been reported to decrease oxalate excretion in patients with enteric hyperoxaluria, but none of these studies was performed under ambulatory conditions. This study describes the effects of these treatments on the urinary composition of patients with hyperoxaluria after jejunoileal bypass operation under out-patient conditions.

Hyperparathyroidism in Urolithiasis

It is very clear that hyperparathyroidism (HPT) is diagnosed earlier today than 30 years ago. This can be explained by an increased interest in this disease and by the relative ease with which serum calcium can be determined. An earlier diagnosis, however, has also caused a shift in the clinical spectrum of HPT. Today it is very rare to see a patient with an extensive bone involvement and one can no longer consider hyperparathyroidism “a disease of bone and stone” as Albright did in 1935.