What type of kidney stones are radiopaque on KUB?

• A. Uric acid stones
• B. Struvite and calcium stones
• C. Calcium oxalate stones only
• D. Both struvite and uric acid stones

Answer: (B)

Struvite and calcium stones are radiopaque on a kidney, ureter, and bladder (KUB) X-ray. These stones are composed of substances that contain calcium or magnesium, making them dense enough to be visible on radiographic imaging. Struvite stones, in particular, form in response to urinary tract infections and are made of magnesium ammonium phosphate, while calcium stones are typically composed of calcium oxalate or calcium phosphate. Both types exhibit sufficient mineral content to absorb X-rays, which allows them to appear on the KUB film.

In contrast, uric acid stones are radiolucent, meaning they do not appear on KUB films. They are less dense and do not contain the same level of minerals that contribute to radiopacity. Calcium oxalate stones are also considered radiopaque, but since the correct answer encompasses both struvite and calcium stones, the inclusion of struvite with calcium makes the selection correct. Thus, the combination of struvite and calcium stones provides the comprehensive answer regarding radiopacity on KUB imaging.