Mathematical model to estimate risk of calcium-containing renal stones

Background/Aims: Astronauts exposed to microgravity during the course of sp aceflight undergo physiologic changes that alter the urinary environment so as to increase the risk of renal stone formation. This study was undertake n to identify a simple method with which to evaluate the potential risk of renal stone development during spaceflight. Method: We used a large data ba se of urinary risk factors obtained from 323 astronauts before and after sp aceflight to generate a mathematical model with which to predict the urinar y supersaturation of calcium stone forming salts. Result: This model, which involves the fewest possible analytical variables (urinary calcium, citrat e, oxalate, phosphorus, and total volume), reliably and accurately predicte d the urinary supersaturation of the calcium stone forming salts when compa red to results obtained from a group of 6 astronauts who collected urine du ring flight. Conclusions:The use of this model will simplify both routine m edical monitoring during spaceflight as well as the evaluation of counterme asures designed to minimize renal stone development, This model also can be used for Earth-based applications in which access to analytical resources is limited.