What is your approach to differentiating Randall plaques from actual small non-obstructing stones when reviewing imaging testing for your patients with recurrent nephrolithiasis?

In truth, I almost never can tell with present CT imaging. Once we have a URS with images, it is easier in a given case. Even more misleading is plugging, which can be dense looking on CT and essentially in tissues and not amenable to removal, now requiring surgery. Specialized, very high-resolution scanners seem to do better, but I do not have that for my patients at present. Wrap up of this important issue: Right now, we will have URS done, expecting small stones and end up with mostly dense plaque or plugging. The main thing is the images during the procedure compared to CT, so as to make the next try better informed.

Randall‘s plaque represents subepithelial deposits of calcium phosphate in the renal papillae. They typically serve as a nidus for calcium oxalate stones.

Differentiating the two radiographically is challenging. However, they have common risk factors: hypercalciuria and low urine volume.

My approach is to treat both by recommending (1) increased fluid intake, preferably water, aiming for a minimum of 2 L daily, (2) a stone prevention diet as instructed by the Stone Clinic dietitian, and if follow-up CT scans show an increase in calcification, (3) adding a thiazide to reduce hypercalciuria and/or potassium citrate to increase hypocitraturia.

I don't worry about the distinction, since that would not impact my recommendations for lowering risk for stones. In a previously identified stone former, the goal is to prevent the accumulation of stones, so this finding would simply establish the state of their disease at a time point that can be referenced in treatment follow-up imaging. If this were a new imaging finding, I would still recommend standard treatments for calcium stones (e.g., increased urine volumes and adequate calcium in the diet), with similar repeat imaging to assess response to therapy, since Randall's plaques are recognized as a risk factor in calcium oxalate disease.