A path analysis to investigate the interaction between serum, urinary and demographic factors influencing urine calcium in kidney stone formers.

Serum 25(OH)D and phosphorus, along with age and weight, indirectly affected urinary calcium through a third variable. Other variables (PTH, serum creatinine, and 24-U sodium, urea, and citrate) showed a direct effect on 24-U calcium excretion.