What is your approach for patients with recurrent nephrolithiasis who you have a strong suspicion for primary hyperoxaluria though genetic testing returns without any abnormalities?  

As an adult nephrologist, most of my patients with oxalosis have enteric hyperoxaluria. I suggest you take a careful history, looking for inflammatory bowel disease, removal of small bowel or surgical rerouting of the intestines. If your patient is a child, I would explore the possibility of insura...