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J Urol. 2003 Mar;169(3):863-6.

Changes in urine volume accomplished by physicians treating nephrolithiasis.

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Nephrology Section, University of Chicago, Illinois, USA.



We quantified the changes in urine volume and sodium accomplished in various practice settings and the consequent effects on calcium oxalate supersaturation.


We determined comprehensive urine stone risk factors in 2,877 patients treated in 14 practices, including a university referral center and private sector practices. Changes in urine volume and stone risk factors were measured.


In a wide range of practice settings the volume increase was about 0.3 l. daily. Urine sodium excretion increased with volume for unexplained reasons, as did urine calcium excretion. As expected, thiazide lowered calcium excretion but the effect progressively decreased as urine volume increased. Therefore, urine calcium and calcium oxalate supersaturation changes were the result of opposing forces. The net effect was a decrease partly offset by sodium and calcium excretion increases.


Urine volume increments are modest in practice and they are modestly offset by increases in urine sodium due to increased sodium intake. Clinicians should strive for higher volume increases than are currently achieved and be vigilant concerning what seems to be a strong tendency toward a higher sodium intake with more fluids.

[Indexed for MEDLINE]

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