Reviewing Your ABCs - Acute Kidney Injury, Bartonella Endocarditis, and C-ANCA Vasculitis

A 67-year-old man presented to the emergency department with epistaxis, pancytopenia, and renal failure (creatinine, 633 umol/L; normal, 52-112 umol/L). He was recently diagnosed with cytoplasmic-antineutrophil cytoplasmic autoantibody (c-ANCA)-associated glomerulonephritis. Three weeks earlier, he presented with new-onset renal failure (creatinine, 738 umol/L), hyperkalemia (6.2 mmol/L; normal, 3.5-5.0 umol/L), and normocytic anemia (hemoglobin, 91 g/L; normal, 130-170 g/L). Urine microscopy revealed red blood cell and heme granular casts, concerning for rapidly progressive glomerulonephritis. Autoimmune investigations were positive for PR3 (c-ANCA) (>200 RU/mL; normal, <20 RU/mL) and low complement (C3 and C4) levels. Cryocrit was positive (normal; negative). Antineutrophil cytoplasmic autoantibody autoantibodies to myeloperoxidase (p-ANCA) were negative. Initial investigations for infectious etiologies including blood cultures, hepatitis B surface antigen and core antibody, hepatitis C antibody, and HIV serology were negative. A diagnosis of c-ANCA-associated pauci-immune glomerulonephritis was made based on serologic findings. He was treated with oral cyclophosphamide and prednisone.