You are viewing a “KUB” (plain abdominal) x-ray film of a 45-year-old woman who has a history of left bifid ureter and pyelonephritis at least once. You see an opacity that fills and outlines the pelvis of the left kidney. What is the basis and content of this calcification?
(A) Uric acid in hyperuricemia
(B) Calcium oxalate from chronic infection
© Calcium oxalate from hypercalciuria
(D) Magnesium ammonium phosphate from urease-producing organisms
(E) Cysteine caused by hypercysteinuria
The answer is D, magnesium ammonium phosphate from urease-producing organisms. These are called struvite stones, and insofar as they become molded by the calyceal collecting system, they are often referred to as “staghorn” calculi.