title: An unexpected cause of acute kidney injury in a patient with ANCA associated vasculitis.
abstract: Diagnostic kidney biopsies sometimes yield clinically unsuspected diagnoses. We present a case of a 69-year-old woman with established ANCA-associated vasculitis (AAV) of 4 years duration who was in clinical remission following cytotoxic therapy and was on maintenance immunosuppression. She presented to the hospital with acute kidney injury (AKI), symptoms suggestive of a systemic vasculitis, and in addition had hypercalcemia, metabolic alkalosis. A relapse in the AAV was suspected but a diagnostic kidney biopsy showed acute tubular necrosis, patchy interstitial inflammation, and calcium phosphate deposits. It was found that the patient recently started consuming large doses of over-the-counter calcium-containing antacids and vitamin Dcontaining multivitamin supplements. Cessation of these drugs led to improvement of renal function to baseline. This case highlights several teaching points: (1) the kidney biopsy can prove to be critically important even in cases where there appears to be a more obvious clinical diagnosis, (2) AK due to calcium-alkali syndrome has characteristic histopathological changes, and (3) that the triad of hypercalcemia, metabolic alkalosis, and AKI is exclusively associated with the ingestion of excessive quantities of calcium-containing antacids. The physician should keep this in mind, and pro-actively seek pertinent medication history from the patient. A brief review of calcium-alkali syndrome is given.
authors.forename: Wajid M
authors.initials: WM
authors.lastname: Choudhry
authors.forename: Uday S
authors.initials: US
authors.lastname: Nori
authors.forename: Tibor
authors.initials: T
authors.lastname: Nadasdy
authors.forename: Anjali A
authors.initials: AA
authors.lastname: Satoskar
mesh_terms: D058186:Acute Kidney Injury / Q000209:etiology*; D000368:Aged; D000471:Alkalosis / Q000139:chemically induced; D000863:Antacids / Q000009:adverse effects*; D056648:Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis / Q000188:drug therapy; D002118:Calcium / Q000009:adverse effects*; D019587:Dietary Supplements / Q000009:adverse effects*; D005260:Female; D006801:Humans; D006934:Hypercalcemia / Q000139:chemically induced; D007683:Kidney Tubular Necrosis, Acute / Q000473:pathology; D014807:Vitamin D / Q000009:adverse effects*
chemical_list: D000863:Antacids; D014807:Vitamin D; D002118:Calcium