An unexpected cause of acute kidney injury in a patient with ANCA associated vasculitis.

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.

Comparison of low-dose gentamicin with minocycline as catheter lock solutions in the prevention of catheter-related bacteremia.

BACKGROUND: Catheter-restricted antibiotic lock solutions were found to be effective in the prevention of catheter-related bacteremia (CRB), but insufficient data are available about the ideal agent and dose. We hypothesized that a low concentration of gentamicin would be as effective as the high doses studied in the past. METHODS: In this prospective, open-labeled, randomized, clinical trial of patients on long-term hemodialysis therapy, patients were randomly assigned to administration of an antibiotic lock solution of gentamicin/citrate (4 mg/mL), minocycline/EDTA, or the control solution of heparin. Patients were followed up until the study end point of CRB was reached or a censoring event occurred. Interim data analysis was performed after 6 months to assess data safety; efficacy was noted and the study was terminated early. RESULTS: Sixty-two patients were enrolled into the study, evenly distributed in 3 arms, with data from 1 patient excluded from analysis. Seven of 20 patients in the heparin group (4.0 events/1,000 catheter days), 1 of 21 patients in the minocycline group (0.4 events/1,000 catheter days), and none of 20 patients in the gentamicin group developed bacteremia. Results were statistically significant by using 2-tailed Fisher exact test; heparin versus gentamicin, P = 0.008, and heparin versus minocycline, P = 0.020. CONCLUSION: Antibiotic lock solutions are superior to the standard heparin lock alone in the prevention of CRBs, and low-dose gentamicin solution has efficacy similar to that of greater concentrations used in previous studies.