Patent ID: 6991937

Claim:
A method for determining the level of cystine supersaturation in a patient urine sample comprising a. adding to said patient urine sample a measured amount of solid phase cystine to form a cystine/urine sample; b. incubating said cystine/urine sample under conditions that permit dissolution of said solid phase cystine until equilibrium is reached with undissolved residual solid phase cystine to form an equilibrium mixture; c. separating said residual solid phase cystine from said equilibrium mixture to form a cystine pellet; d. completely dissolving said cystine pellet in a cystine-dissolving agent to form a final cystine solution; e. measuring the amount of cystine dissolved in said final cystine solution; and f. subtracting the amount of cystine dissolved in said final cystine solution from said measured amount of solid phase cystine to obtain a calculated value for the amount of dissolved solid phase cystine in said equilibrium mixture, whereby said amount of dissolved solid phase cystine in said equilibrium mixture is an indicator of urine cystine supersaturation.