What is your approach for managing patients with recurrent nephrolithiasis who have elevated urinary cystine levels but calcium oxalate stone composition?

This is usually heterozygous cystinuria, and the urine cystine is in the range of 50 mg. Supersaturation with cystine is absent, and the cystine can be ignored. Rarely, urine cystine is high enough to produce stones, and I treat both stone risk factors. In all cases where urine cystine is above 100 ...

I agree with Dr. @Dr. First Last that this is a case of heterozygous cystinuria, and the patient is unlikely to make cystine stones in the future. That said, after standard fluid and dietary recommendations, I would choose potassium citrate as my medication of choice. It is effective against calcium...

Elevated urine cystine levels can encompass a large range of values from a few hundred mg per day to over 1,000 mg. A patient at the lower end of that range might not form cystine stones with ordinary urine volumes (1.5 to 2 L per day), but they could have a risk for calcium oxalate stones at that v...

I agree with Drs. @Dr. First Last and @Dr. First Last. I also would agree to adding K citrate to make sure the pH remains alkaline.