NORMAL CALCIUM-OXALATE CRYSTAL-GROWTH INHIBITION IN SEVERE CALCIUM-OXALATE NEPHROLITHIASIS

Urine from mammalian kidneys is regularly supersaturated with respect to calcium oxalate monohydrate, the most common solid phase in human n ephrolithiasis, and also inhibits the nucleation, growth, and aggregat ion of calcium oxalate crystals, Nephrolithiasis is often associated w ith increased supersaturation, and it is assumed that this increase ov erbalances the inhibition effects, causing stones. However, some patie nts form stones in the absence of increased supersaturation, and in th ose patients, one might assume that reduced inhibition is the cause of their stones. This hypothesis was tested in 25 patients who formed at least ten stones each, yet lacked the usual metabolic abnormalities t hat increase supersaturation. Compared with 25 age- and sex-matched co ntrol subjects, urine supersaturation among the patients was not incre ased; this is an expected result of this study's selection criteria, C ompared with the same age- and sex-matched control subjects, urine fro m the patients showed no evidence for reduced inhibition of calcium ox alate crystal growth, so low inhibition of growth did not contribute t o pathogenesis of stones in our highly selected study population, desp ite their otherwise unexplained and active stone formation, These resu lts do not support the hypothesis that growth inhibition defects are a cause of stone disease.