Nephrocalcinosis, the deposition of calcium phosphate crystals within renal tubules and sometimes within interstitium, may occur at any age. Patients may present with acute kidney injury (AKI). In patients with acute phosphate nephropathy, progression to end-stage kidney disease (ESKD) can occur, particularly if there is pre-existing chronic kidney disease (CKD). Acute phosphate nephropathy typically occurs due to a large load of oral sodium phosphate as part of colonoscopy preparation, and presents as AKI, developing in 1 in 1,000 to 5,000 of such patients.