are we talking about uric acid, and does the person have uric acid stones?

One thing you can do that I bet most people don't think about is check the
mineral concentrations in you ground water.  The area I'm in is sitting on
top of limestone bedrock.  This results in the water having high
concentrations of calcite (?).  Anyway,  instances of kidney stones are
four times greater in this area than the national average.  I've taken to
drinking bottled water.