Three hundred and ninety-two stone formers were investigated to exclude systemic disorders and to define the presence of haematological and urinary abnormality commonly associated with stone disease. Increased urinary excretion of calcium, oxalate or uric acid was found in 40% and there was more than one abnormality in 16% of the patients. The dietary habit of stone formers did not differ significantly from that of control subjects. Dietary advice to increase the consumption of fibre and reduce the consumption of sugar, refined carbohydrates and animal protein produced a significant reduction in the urinary excretion of calcium, oxalate and uric acid. We consider that reduction of the nutrient density of the diet by this means is the first line of management of idiopathic stone formers.

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There is evidence to suggest that sucrose ingestion can cause renal parenchymal changes as well as increasing the urinary saturation index for calcium oxalate. Ten stone formers and 10 normal subjects received 250 gm of sucrose daily over a period of 7 days. Observations on the risk factors for calcium stone formation and urinary N-acetyl-B-glucosaminidase (NAG), a marker of renal tubular cell damage, were made. Oxalate excretion increased. Urinary calcium levels were unchanged but the pattern of response was different between the two groups, as with magnesium and phosphate. NAG was spontaneously higher in the patient group and increased significantly after sucrose ingestion in both groups.

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