The Impact of Diet on Urinary Risk Factors for Cystine Stone Formation.

Roswitha Siener,Albrecht Hesse,Norman Bitterlich,Hubert Birwé

doi:10.3390/nu13020528

Abstract

Despite the importance of dietary management of cystinuria, data on the contribution of diet to urinary risk factors for cystine stone formation are limited. Studies on the physiological effects of diet on urinary cystine and cysteine excretion are lacking. Accordingly, 10 healthy men received three standardized diets for a period of five days each and collected daily 24 h urine. The Western-type diet (WD; 95 g/day protein) corresponded to usual dietary habits, whereas the mixed diet (MD; 65 g/day protein) and lacto-ovo-vegetarian diet (VD; 65 g/day protein) were calculated according to dietary reference intakes. With intake of the VD, urinary cystine and cysteine excretion decreased by 22 and 15%, respectively, compared to the WD, although the differences were not statistically significant. Urine pH was significantly highest on the VD. Regression analysis showed that urinary phosphate was significantly associated with cystine excretion, while urinary sulfate was a predictor of cysteine excretion. Neither urinary cystine nor cysteine excretion was affected by dietary sodium intake. A lacto-ovo-vegetarian diet is particularly suitable for the dietary treatment of cystinuria, since the additional alkali load may reduce the amount of required alkalizing agents.

Highlights

Cystinuria accounts for less than 1% of urinary stones in adults but up to 8% of urolithiasis in children and adolescents [1,2]
Both urinary cystine and cysteine excretion tended to be lower on the vegetarian diet (VD) compared to the Western-type diet (WD), the differences were not statistically significant
Urinary cystine concentration was significantly lower on the mixed diet (MD) and VD compared to the WD due to significant differences in urinary volume, which is reflected by urine density

Summary

Introduction

Cystinuria accounts for less than 1% of urinary stones in adults but up to 8% of urolithiasis in children and adolescents [1,2]. Cystinuria is a genetic disorder of the proximal tubular reabsorption of cystine and the dibasic amino acids arginine, ornithine, and lysine [3,4,5,6]. The hyperexcretion and poor solubility of cystine in urine can lead to crystallization and a lifetime risk of recurrent stone formation. For patients who fail to respond to dietary measures and alkali therapy, pharmacotherapy with the currently available chelating thiol drugs, alphamercaptopropionyl glycine and D-penicillamine, is indicated. A variety of side effects, such as alterations in taste perception, mucocutaneous lesions, immune-mediated diseases, hematological reactions, proteinuria, and nephrotic syndrome, may necessitate discontinuation of medical therapy [8]

Results

Discussion

Conclusion