Oxalic acid stone formers

Table 1 Glucose utilisation coefficients in controls, oxalic and uric acid stone formers, primary hyperparathyroidism.

An additional observation, hinting indirectly at the parallelism between uric acid and calcium in urine, is the high coincidence of uric acid and calcium crystalluria in the group of recurrent stone formers that has been measured in 16 (oxalate and urate) stone patients and in 11 controls during our long-term study. Twenty-eight percent of all urine samples collected in male stone patients and thirty-one percent of those collected in female patients contained both calcium and uric acid crystals. 

The graph of the mean values of the urinary uric acid blearly shows the rapid increase of the uric acid excretion in the control group, followed by an equally fast decrease (Fig. 1). On the other hand, the increase of the mixed stone formers is much smaller and of no significance, remaining almost unchanged on the second day. There is also a clear increase in the pure calcium oxalate stones, but a smaller decrease on the second day. 

When comparing serum uric acid in 57 Ca oxalate stone formers and 25 controls on unrestricted diet we found on average higher values in the patients. This is also evident when subdividing the groups into male and female (Tab. 1). 

Table 1 Comparison of serum uric acid in Ca oxalate stone formers and healthy controls in relation to sex.

In recent years investigations have been carried out by our group with 2 g of a guanine/ adenine mixture. Following this oral load the serum uric acid of Ca oxalate stone formers showed a significant increase, which remained for several days. In healthy controls the serum uric acid had returned to basic preload level on the second day after the load (Fig. 3). 

Serum uric acid is higher on average in Ca oxalate stone formers than in healthy controls. 

There is no difference in the uric acid excretion of Ca oxalate stone formers on unrestricted and on standardized diet. 

Fig. 2 Excretion and concentration of uric acid in 24-h urine after application of a benzbromarone-citrate mixture (Harolan ) in 21 calcium oxalate stone formers on standard diet. 

Fig. 3 Solubility of uric acid in synthetic urine (Berenyi 1972) and uric acid values of 21 calcium oxalate stone formers on 1st an d 2nd day with Harolan . x on 3rd, 4 th, and 5th day with Harolan .

Fig. 6 Circadian rhythm of uric acid and pH in 21 calcium oxalate stone formers after application of Harolan .

The benzbromarone-citrate mixture Harolan was examined in 21 calcium oxalate stone formers for its value as a prophylactic agent in the treatment of relapses of uric acid- and calcium oxalate stones. The examinations were administered in conjunction with a standard diet in an effort to eliminate the variabilities of excretion of lithogenous and inhibitory substances through individual eating habits. 

METABOLIC AND GLUCOSE LOAD STUDIES IN URIC ACID, OXALIC AND HYPERPARATHYROID STONE FORMERS... 

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