MPO and chronic kidney disease: Laboratory tests revealed urea 72 mg/dL, creatinine 2.65 mg/dL (eGFR CKD-EPI: 20 mL/min/1.73 m<sup>2</sup>), urine analysis with >100 red blood cells per high-power field, 24 h-proteinuria: 1.3 g, hemoglobin 6.6 g/dL, white-cell count 7700/mm<sup>3</sup>, platelets 238,000/mm<sup>3</sup>, complement within the normal range, negative viral serological tests and ANCA positive 1:80 myeloperoxidase pattern.