A 23-year-old man with no relevant medical history or active medication presented with gross hematuria and hypogastric pain. Kidney ultrasound revealed medullary hyperechogenicity, suggestive of nephrocalcinosis, and bilateral cysts (Fig 1). A month later, he developed acute renal colic secondary to an obstructive 14 mm stone located in the right pyeloureteral junction, requiring placement of a double J stent. The stone was removed by ureterorenoscopy. Infrared spectroscopy showed the stone to be of mixed type: carbapatite, brushite, and calcium oxalate mono- and dihydrate.