CORRESPONDENCE BETWEEN STONE COMPOSITION AND URINE SUPERSATURATION INNEPHROLITHIASIS

Supersaturation (SS) with respect to calcium oxalate monohydrate (COM) , brushite (Br) and uric acid (UA), obtained in three 24-hour pretreat ment urine samples from patients with stone disease were compared to t he mineral composition of stones passed by the same patients to determ ine whether sparse urine SS measurements accurately reflect the long-t erm average SS values in the kidney and final urine. Among males and f emales elevation of SS above same sex normals corresponded to composit ion. As well, treatments that reduced stone rates also reduced these S S values. The degree of calcium phosphate (CaP) admixture was accurate ly matched by shifting magnitudes of COM and Br SS. As well, increasin g CaP content was associated with falling urine citrate and rising uri ne pH, suggesting renal tubular acidosis. We conclude that sparse urin e SS measurements accurately track stone admixtures, and are a reliabl e index of average renal and urine SS.