Urinary stone formation in patients with CKD

Felix Knauf is a professor of nephrology at the Charité – Universitätsmedizin Berlin, Germany, and an assistant professor adjunct at Yale University.

What is the risk of urinary stone formation (uric acid, calcium oxalate) in patients with chronic kidney disease (CKD) of variable severity?

What we do know is that certain diseases that also cause CKD are associated with a higher risk of kidney stones. For example, diabetes, the main driver for CKD, is also associated with a higher risk of uric acid stones, but also oxalate stones, because there’s a tendency that, as we have learned in the last years, there seems to be a higher oxalate excretion in diabetic patients. Of course, uric acid stones are being observed specifically in diabetics, as I mentioned, but also in patients with gout. So, the same risk factors that lead to CKD are also associated with stone disease in itself.

To my knowledge, there are no clinical data at this point looking at the severity of CKD, meaning stage 1, 2, 3, 4, and 5, and the kinds of stones that are being observed. That study still needs to be done to see whether, for example, the stage 4 changes the stone prevalence versus stage 2 or 1.